| Message ID | 1458341063-8753-1-git-send-email-gabriele.mzt@gmail.com (mailing list archive) |
|---|---|
| State | Accepted, archived |
| Headers | show |
On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote: > +#ifdef CONFIG_PM_SLEEP > +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context) > +{ > + struct rbtn_data *rbtn_data = context; > + > + rbtn_data->suspended = false; > +} > + > +static int rbtn_suspend(struct device *dev) > +{ > + struct acpi_device *device = to_acpi_device(dev); > + struct rbtn_data *rbtn_data = acpi_driver_data(device); > + > + rbtn_data->suspended = true; > + > + return 0; > +} > + > +static int rbtn_resume(struct device *dev) > +{ > + struct acpi_device *device = to_acpi_device(dev); > + struct rbtn_data *rbtn_data = acpi_driver_data(device); > + acpi_status status; > + > + /* > + * Clear the flag only after we received the extra > + * ACPI notification. > + */ > + status = acpi_os_execute(OSL_NOTIFY_HANDLER, > + rbtn_acpi_clear_flag, rbtn_data); > + if (ACPI_FAILURE(status)) > + rbtn_data->suspended = false; I case when acpi_os_execute success it calls rbtn_acpi_clear_flag, right? And that will set suspended to false. When acpi_os_execute fails, then it set suspended too to false... Then whole acpi_os_execute doing just "barrier" after which suspended flag can be set to false. So I think rbtn_acpi_clear_flag function is not needed here. Cannot you pass NULL or empty function pointer as callback? Or what was reason to do that flag clearing at "two places"? > + return 0; > +} > +#endif
2016-03-21 13:17 GMT+01:00 Pali Rohár <pali.rohar@gmail.com>: > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote: >> +#ifdef CONFIG_PM_SLEEP >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context) >> +{ >> + struct rbtn_data *rbtn_data = context; >> + >> + rbtn_data->suspended = false; >> +} >> + >> +static int rbtn_suspend(struct device *dev) >> +{ >> + struct acpi_device *device = to_acpi_device(dev); >> + struct rbtn_data *rbtn_data = acpi_driver_data(device); >> + >> + rbtn_data->suspended = true; >> + >> + return 0; >> +} >> + >> +static int rbtn_resume(struct device *dev) >> +{ >> + struct acpi_device *device = to_acpi_device(dev); >> + struct rbtn_data *rbtn_data = acpi_driver_data(device); >> + acpi_status status; >> + >> + /* >> + * Clear the flag only after we received the extra >> + * ACPI notification. >> + */ >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER, >> + rbtn_acpi_clear_flag, rbtn_data); >> + if (ACPI_FAILURE(status)) >> + rbtn_data->suspended = false; > > I case when acpi_os_execute success it calls rbtn_acpi_clear_flag, > right? And that will set suspended to false. When acpi_os_execute fails, > then it set suspended too to false... Then whole acpi_os_execute doing > just "barrier" after which suspended flag can be set to false. So I > think rbtn_acpi_clear_flag function is not needed here. > > Cannot you pass NULL or empty function pointer as callback? Or what was > reason to do that flag clearing at "two places"? acpi_os_execute doesn't wait for the callback to be executed, so I can't clear the flag from rbtn_resume. >> + return 0; >> +} >> +#endif > > -- > Pali Rohár > pali.rohar@gmail.com -- To unsubscribe from this list: send the line "unsubscribe platform-driver-x86" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote: > 2016-03-21 13:17 GMT+01:00 Pali Rohár <pali.rohar@gmail.com>: > > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote: > >> +#ifdef CONFIG_PM_SLEEP > >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context) > >> +{ > >> + struct rbtn_data *rbtn_data = context; > >> + > >> + rbtn_data->suspended = false; > >> +} > >> + > >> +static int rbtn_suspend(struct device *dev) > >> +{ > >> + struct acpi_device *device = to_acpi_device(dev); > >> + struct rbtn_data *rbtn_data = acpi_driver_data(device); > >> + > >> + rbtn_data->suspended = true; > >> + > >> + return 0; > >> +} > >> + > >> +static int rbtn_resume(struct device *dev) > >> +{ > >> + struct acpi_device *device = to_acpi_device(dev); > >> + struct rbtn_data *rbtn_data = acpi_driver_data(device); > >> + acpi_status status; > >> + > >> + /* > >> + * Clear the flag only after we received the extra > >> + * ACPI notification. > >> + */ > >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER, > >> + rbtn_acpi_clear_flag, rbtn_data); > >> + if (ACPI_FAILURE(status)) > >> + rbtn_data->suspended = false; > > > > I case when acpi_os_execute success it calls rbtn_acpi_clear_flag, > > right? And that will set suspended to false. When acpi_os_execute fails, > > then it set suspended too to false... Then whole acpi_os_execute doing > > just "barrier" after which suspended flag can be set to false. So I > > think rbtn_acpi_clear_flag function is not needed here. > > > > Cannot you pass NULL or empty function pointer as callback? Or what was > > reason to do that flag clearing at "two places"? > > acpi_os_execute doesn't wait for the callback to be executed, so > I can't clear the flag from rbtn_resume. acpi_os_execute calls callback asynchronously later? Or what exactly do it?
2016-03-24 10:39 GMT+01:00 Pali Rohár <pali.rohar@gmail.com>: > On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote: >> 2016-03-21 13:17 GMT+01:00 Pali Rohár <pali.rohar@gmail.com>: >> > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote: >> >> +#ifdef CONFIG_PM_SLEEP >> >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context) >> >> +{ >> >> + struct rbtn_data *rbtn_data = context; >> >> + >> >> + rbtn_data->suspended = false; >> >> +} >> >> + >> >> +static int rbtn_suspend(struct device *dev) >> >> +{ >> >> + struct acpi_device *device = to_acpi_device(dev); >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device); >> >> + >> >> + rbtn_data->suspended = true; >> >> + >> >> + return 0; >> >> +} >> >> + >> >> +static int rbtn_resume(struct device *dev) >> >> +{ >> >> + struct acpi_device *device = to_acpi_device(dev); >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device); >> >> + acpi_status status; >> >> + >> >> + /* >> >> + * Clear the flag only after we received the extra >> >> + * ACPI notification. >> >> + */ >> >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER, >> >> + rbtn_acpi_clear_flag, rbtn_data); >> >> + if (ACPI_FAILURE(status)) >> >> + rbtn_data->suspended = false; >> > >> > I case when acpi_os_execute success it calls rbtn_acpi_clear_flag, >> > right? And that will set suspended to false. When acpi_os_execute fails, >> > then it set suspended too to false... Then whole acpi_os_execute doing >> > just "barrier" after which suspended flag can be set to false. So I >> > think rbtn_acpi_clear_flag function is not needed here. >> > >> > Cannot you pass NULL or empty function pointer as callback? Or what was >> > reason to do that flag clearing at "two places"? >> >> acpi_os_execute doesn't wait for the callback to be executed, so >> I can't clear the flag from rbtn_resume. > > acpi_os_execute calls callback asynchronously later? Or what exactly do it? In this case, it adds the callback to the kacpi_notify_wq workqueue for deferred execution. > -- > Pali Rohár > pali.rohar@gmail.com -- To unsubscribe from this list: send the line "unsubscribe platform-driver-x86" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, Mar 24, 2016 at 12:24:56PM +0100, Gabriele Mazzotta wrote: > 2016-03-24 10:39 GMT+01:00 Pali Rohár <pali.rohar@gmail.com>: > > On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote: > >> 2016-03-21 13:17 GMT+01:00 Pali Rohár <pali.rohar@gmail.com>: > >> > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote: > >> >> +#ifdef CONFIG_PM_SLEEP > >> >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context) > >> >> +{ > >> >> + struct rbtn_data *rbtn_data = context; > >> >> + > >> >> + rbtn_data->suspended = false; > >> >> +} > >> >> + > >> >> +static int rbtn_suspend(struct device *dev) > >> >> +{ > >> >> + struct acpi_device *device = to_acpi_device(dev); > >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device); > >> >> + > >> >> + rbtn_data->suspended = true; > >> >> + > >> >> + return 0; > >> >> +} > >> >> + > >> >> +static int rbtn_resume(struct device *dev) > >> >> +{ > >> >> + struct acpi_device *device = to_acpi_device(dev); > >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device); > >> >> + acpi_status status; > >> >> + > >> >> + /* > >> >> + * Clear the flag only after we received the extra > >> >> + * ACPI notification. > >> >> + */ > >> >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER, > >> >> + rbtn_acpi_clear_flag, rbtn_data); > >> >> + if (ACPI_FAILURE(status)) > >> >> + rbtn_data->suspended = false; > >> > > >> > I case when acpi_os_execute success it calls rbtn_acpi_clear_flag, > >> > right? And that will set suspended to false. When acpi_os_execute fails, > >> > then it set suspended too to false... Then whole acpi_os_execute doing > >> > just "barrier" after which suspended flag can be set to false. So I > >> > think rbtn_acpi_clear_flag function is not needed here. > >> > > >> > Cannot you pass NULL or empty function pointer as callback? Or what was > >> > reason to do that flag clearing at "two places"? > >> > >> acpi_os_execute doesn't wait for the callback to be executed, so > >> I can't clear the flag from rbtn_resume. > > > > acpi_os_execute calls callback asynchronously later? Or what exactly do it? > > In this case, it adds the callback to the kacpi_notify_wq workqueue > for deferred execution. +Rafael for context/advice on the use of acpi_os_execute here. This is true, but a quick scan through that call path doesn't tell me why we would need to call it here instead of just setting rbtn_data->suspended = false. The comment suggests waiting for the event, but is that what this is doing? It appears to me to be immediately scheduling the function to a work queue, not waiting for the event notifier. Also, since there is no indication to the user that a failure occurs, this function is basically equivalent in the success and failure case (the success case is just slower). Am I missing something critical here? > > > -- > > Pali Rohár > > pali.rohar@gmail.com >
2016-03-28 19:33 GMT+02:00 Darren Hart <dvhart@infradead.org>: > On Thu, Mar 24, 2016 at 12:24:56PM +0100, Gabriele Mazzotta wrote: >> 2016-03-24 10:39 GMT+01:00 Pali Rohár <pali.rohar@gmail.com>: >> > On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote: >> >> 2016-03-21 13:17 GMT+01:00 Pali Rohár <pali.rohar@gmail.com>: >> >> > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote: >> >> >> +#ifdef CONFIG_PM_SLEEP >> >> >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context) >> >> >> +{ >> >> >> + struct rbtn_data *rbtn_data = context; >> >> >> + >> >> >> + rbtn_data->suspended = false; >> >> >> +} >> >> >> + >> >> >> +static int rbtn_suspend(struct device *dev) >> >> >> +{ >> >> >> + struct acpi_device *device = to_acpi_device(dev); >> >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device); >> >> >> + >> >> >> + rbtn_data->suspended = true; >> >> >> + >> >> >> + return 0; >> >> >> +} >> >> >> + >> >> >> +static int rbtn_resume(struct device *dev) >> >> >> +{ >> >> >> + struct acpi_device *device = to_acpi_device(dev); >> >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device); >> >> >> + acpi_status status; >> >> >> + >> >> >> + /* >> >> >> + * Clear the flag only after we received the extra >> >> >> + * ACPI notification. >> >> >> + */ >> >> >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER, >> >> >> + rbtn_acpi_clear_flag, rbtn_data); >> >> >> + if (ACPI_FAILURE(status)) >> >> >> + rbtn_data->suspended = false; >> >> > >> >> > I case when acpi_os_execute success it calls rbtn_acpi_clear_flag, >> >> > right? And that will set suspended to false. When acpi_os_execute fails, >> >> > then it set suspended too to false... Then whole acpi_os_execute doing >> >> > just "barrier" after which suspended flag can be set to false. So I >> >> > think rbtn_acpi_clear_flag function is not needed here. >> >> > >> >> > Cannot you pass NULL or empty function pointer as callback? Or what was >> >> > reason to do that flag clearing at "two places"? >> >> >> >> acpi_os_execute doesn't wait for the callback to be executed, so >> >> I can't clear the flag from rbtn_resume. >> > >> > acpi_os_execute calls callback asynchronously later? Or what exactly do it? >> >> In this case, it adds the callback to the kacpi_notify_wq workqueue >> for deferred execution. > > +Rafael for context/advice on the use of acpi_os_execute here. > > This is true, but a quick scan through that call path doesn't tell me why we > would need to call it here instead of just setting rbtn_data->suspended = false. > The comment suggests waiting for the event, but is that what this is doing? It > appears to me to be immediately scheduling the function to a work queue, not > waiting for the event notifier. > > Also, since there is no indication to the user that a failure occurs, this > function is basically equivalent in the success and failure case (the success > case is just slower). > > Am I missing something critical here? Maybe saying that we are waiting for the extra event is not really correct. Since the extra ACPI notification is processed by means of kacpi_notify_wq, or at least that's my understanding, our callback is likely going to be executed after we received the extra ACPI notification. This was suggested by Rafael [2]. The problem with setting the flag directly from the resume callback is that the extra notification might arrive after we cleared the flag, causing spurious input events [1]. [1] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8001 [2] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8201 > >> >> > -- >> > Pali Rohár >> > pali.rohar@gmail.com >> > > -- > Darren Hart > Intel Open Source Technology Center -- To unsubscribe from this list: send the line "unsubscribe platform-driver-x86" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, Mar 28, 2016 at 07:58:09PM +0200, Gabriele Mazzotta wrote: > 2016-03-28 19:33 GMT+02:00 Darren Hart <dvhart@infradead.org>: > > On Thu, Mar 24, 2016 at 12:24:56PM +0100, Gabriele Mazzotta wrote: > >> 2016-03-24 10:39 GMT+01:00 Pali Rohár <pali.rohar@gmail.com>: > >> > On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote: > >> >> 2016-03-21 13:17 GMT+01:00 Pali Rohár <pali.rohar@gmail.com>: > >> >> > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote: > >> >> >> +#ifdef CONFIG_PM_SLEEP > >> >> >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context) > >> >> >> +{ > >> >> >> + struct rbtn_data *rbtn_data = context; > >> >> >> + > >> >> >> + rbtn_data->suspended = false; > >> >> >> +} > >> >> >> + > >> >> >> +static int rbtn_suspend(struct device *dev) > >> >> >> +{ > >> >> >> + struct acpi_device *device = to_acpi_device(dev); > >> >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device); > >> >> >> + > >> >> >> + rbtn_data->suspended = true; > >> >> >> + > >> >> >> + return 0; > >> >> >> +} > >> >> >> + > >> >> >> +static int rbtn_resume(struct device *dev) > >> >> >> +{ > >> >> >> + struct acpi_device *device = to_acpi_device(dev); > >> >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device); > >> >> >> + acpi_status status; > >> >> >> + > >> >> >> + /* > >> >> >> + * Clear the flag only after we received the extra > >> >> >> + * ACPI notification. > >> >> >> + */ > >> >> >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER, > >> >> >> + rbtn_acpi_clear_flag, rbtn_data); > >> >> >> + if (ACPI_FAILURE(status)) > >> >> >> + rbtn_data->suspended = false; > >> >> > > >> >> > I case when acpi_os_execute success it calls rbtn_acpi_clear_flag, > >> >> > right? And that will set suspended to false. When acpi_os_execute fails, > >> >> > then it set suspended too to false... Then whole acpi_os_execute doing > >> >> > just "barrier" after which suspended flag can be set to false. So I > >> >> > think rbtn_acpi_clear_flag function is not needed here. > >> >> > > >> >> > Cannot you pass NULL or empty function pointer as callback? Or what was > >> >> > reason to do that flag clearing at "two places"? > >> >> > >> >> acpi_os_execute doesn't wait for the callback to be executed, so > >> >> I can't clear the flag from rbtn_resume. > >> > > >> > acpi_os_execute calls callback asynchronously later? Or what exactly do it? > >> > >> In this case, it adds the callback to the kacpi_notify_wq workqueue > >> for deferred execution. > > > > +Rafael for context/advice on the use of acpi_os_execute here. > > > > This is true, but a quick scan through that call path doesn't tell me why we > > would need to call it here instead of just setting rbtn_data->suspended = false. > > The comment suggests waiting for the event, but is that what this is doing? It > > appears to me to be immediately scheduling the function to a work queue, not > > waiting for the event notifier. > > > > Also, since there is no indication to the user that a failure occurs, this > > function is basically equivalent in the success and failure case (the success > > case is just slower). > > > > Am I missing something critical here? > > Maybe saying that we are waiting for the extra event is not really > correct. Since the extra ACPI notification is processed by means > of kacpi_notify_wq, or at least that's my understanding, our callback > is likely going to be executed after we received the extra ACPI > notification. This was suggested by Rafael [2]. I see, the workqueue is run after the event is issued. If that's the case, how are we ensured that it will get cleared? Isn't it only some systems that have this problem? What happens to the systems that do not send this event at resume? Does the suspended flag remain set? > > The problem with setting the flag directly from the resume callback > is that the extra notification might arrive after we cleared the > flag, causing spurious input events [1]. > > [1] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8001 > [2] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8201 > > > > >> > >> > -- > >> > Pali Rohár > >> > pali.rohar@gmail.com > >> > > > > -- > > Darren Hart > > Intel Open Source Technology Center >
2016-03-28 20:56 GMT+02:00 Darren Hart <dvhart@infradead.org>: > On Mon, Mar 28, 2016 at 07:58:09PM +0200, Gabriele Mazzotta wrote: >> 2016-03-28 19:33 GMT+02:00 Darren Hart <dvhart@infradead.org>: >> > On Thu, Mar 24, 2016 at 12:24:56PM +0100, Gabriele Mazzotta wrote: >> >> 2016-03-24 10:39 GMT+01:00 Pali Rohár <pali.rohar@gmail.com>: >> >> > On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote: >> >> >> 2016-03-21 13:17 GMT+01:00 Pali Rohár <pali.rohar@gmail.com>: >> >> >> > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote: >> >> >> >> +#ifdef CONFIG_PM_SLEEP >> >> >> >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context) >> >> >> >> +{ >> >> >> >> + struct rbtn_data *rbtn_data = context; >> >> >> >> + >> >> >> >> + rbtn_data->suspended = false; >> >> >> >> +} >> >> >> >> + >> >> >> >> +static int rbtn_suspend(struct device *dev) >> >> >> >> +{ >> >> >> >> + struct acpi_device *device = to_acpi_device(dev); >> >> >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device); >> >> >> >> + >> >> >> >> + rbtn_data->suspended = true; >> >> >> >> + >> >> >> >> + return 0; >> >> >> >> +} >> >> >> >> + >> >> >> >> +static int rbtn_resume(struct device *dev) >> >> >> >> +{ >> >> >> >> + struct acpi_device *device = to_acpi_device(dev); >> >> >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device); >> >> >> >> + acpi_status status; >> >> >> >> + >> >> >> >> + /* >> >> >> >> + * Clear the flag only after we received the extra >> >> >> >> + * ACPI notification. >> >> >> >> + */ >> >> >> >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER, >> >> >> >> + rbtn_acpi_clear_flag, rbtn_data); >> >> >> >> + if (ACPI_FAILURE(status)) >> >> >> >> + rbtn_data->suspended = false; >> >> >> > >> >> >> > I case when acpi_os_execute success it calls rbtn_acpi_clear_flag, >> >> >> > right? And that will set suspended to false. When acpi_os_execute fails, >> >> >> > then it set suspended too to false... Then whole acpi_os_execute doing >> >> >> > just "barrier" after which suspended flag can be set to false. So I >> >> >> > think rbtn_acpi_clear_flag function is not needed here. >> >> >> > >> >> >> > Cannot you pass NULL or empty function pointer as callback? Or what was >> >> >> > reason to do that flag clearing at "two places"? >> >> >> >> >> >> acpi_os_execute doesn't wait for the callback to be executed, so >> >> >> I can't clear the flag from rbtn_resume. >> >> > >> >> > acpi_os_execute calls callback asynchronously later? Or what exactly do it? >> >> >> >> In this case, it adds the callback to the kacpi_notify_wq workqueue >> >> for deferred execution. >> > >> > +Rafael for context/advice on the use of acpi_os_execute here. >> > >> > This is true, but a quick scan through that call path doesn't tell me why we >> > would need to call it here instead of just setting rbtn_data->suspended = false. >> > The comment suggests waiting for the event, but is that what this is doing? It >> > appears to me to be immediately scheduling the function to a work queue, not >> > waiting for the event notifier. >> > >> > Also, since there is no indication to the user that a failure occurs, this >> > function is basically equivalent in the success and failure case (the success >> > case is just slower). >> > >> > Am I missing something critical here? >> >> Maybe saying that we are waiting for the extra event is not really >> correct. Since the extra ACPI notification is processed by means >> of kacpi_notify_wq, or at least that's my understanding, our callback >> is likely going to be executed after we received the extra ACPI >> notification. This was suggested by Rafael [2]. > > I see, the workqueue is run after the event is issued. If that's the case, how > are we ensured that it will get cleared? Isn't it only some systems that have > this problem? > > What happens to the systems that do not send this event at resume? Does the > suspended flag remain set? The callback should be executed as long as acpi_os_execute doesn't return an error. If the BIOS doesn't send the extra notification, we uselessly wait for whatever was queued before our callback. On my laptop, the interval between the call to acpi_os_execute and the callback execution is ~200ms (rough existimation using a couple of printks), so not really noticeable. It might be more on some other systems, but I doubt anyone would notice. >> >> The problem with setting the flag directly from the resume callback >> is that the extra notification might arrive after we cleared the >> flag, causing spurious input events [1]. >> >> [1] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8001 >> [2] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8201 >> >> > >> >> >> >> > -- >> >> > Pali Rohár >> >> > pali.rohar@gmail.com >> >> >> > >> > -- >> > Darren Hart >> > Intel Open Source Technology Center >> > > -- > Darren Hart > Intel Open Source Technology Center -- To unsubscribe from this list: send the line "unsubscribe platform-driver-x86" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, Mar 28, 2016 at 09:41:09PM +0200, Gabriele Mazzotta wrote: > 2016-03-28 20:56 GMT+02:00 Darren Hart <dvhart@infradead.org>: > > On Mon, Mar 28, 2016 at 07:58:09PM +0200, Gabriele Mazzotta wrote: > >> 2016-03-28 19:33 GMT+02:00 Darren Hart <dvhart@infradead.org>: > >> > On Thu, Mar 24, 2016 at 12:24:56PM +0100, Gabriele Mazzotta wrote: > >> >> 2016-03-24 10:39 GMT+01:00 Pali Rohár <pali.rohar@gmail.com>: > >> >> > On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote: > >> >> >> 2016-03-21 13:17 GMT+01:00 Pali Rohár <pali.rohar@gmail.com>: > >> >> >> > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote: > >> >> >> >> +#ifdef CONFIG_PM_SLEEP > >> >> >> >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context) > >> >> >> >> +{ > >> >> >> >> + struct rbtn_data *rbtn_data = context; > >> >> >> >> + > >> >> >> >> + rbtn_data->suspended = false; > >> >> >> >> +} > >> >> >> >> + > >> >> >> >> +static int rbtn_suspend(struct device *dev) > >> >> >> >> +{ > >> >> >> >> + struct acpi_device *device = to_acpi_device(dev); > >> >> >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device); > >> >> >> >> + > >> >> >> >> + rbtn_data->suspended = true; > >> >> >> >> + > >> >> >> >> + return 0; > >> >> >> >> +} > >> >> >> >> + > >> >> >> >> +static int rbtn_resume(struct device *dev) > >> >> >> >> +{ > >> >> >> >> + struct acpi_device *device = to_acpi_device(dev); > >> >> >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device); > >> >> >> >> + acpi_status status; > >> >> >> >> + > >> >> >> >> + /* > >> >> >> >> + * Clear the flag only after we received the extra > >> >> >> >> + * ACPI notification. > >> >> >> >> + */ > >> >> >> >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER, > >> >> >> >> + rbtn_acpi_clear_flag, rbtn_data); > >> >> >> >> + if (ACPI_FAILURE(status)) > >> >> >> >> + rbtn_data->suspended = false; > >> >> >> > > >> >> >> > I case when acpi_os_execute success it calls rbtn_acpi_clear_flag, > >> >> >> > right? And that will set suspended to false. When acpi_os_execute fails, > >> >> >> > then it set suspended too to false... Then whole acpi_os_execute doing > >> >> >> > just "barrier" after which suspended flag can be set to false. So I > >> >> >> > think rbtn_acpi_clear_flag function is not needed here. > >> >> >> > > >> >> >> > Cannot you pass NULL or empty function pointer as callback? Or what was > >> >> >> > reason to do that flag clearing at "two places"? > >> >> >> > >> >> >> acpi_os_execute doesn't wait for the callback to be executed, so > >> >> >> I can't clear the flag from rbtn_resume. > >> >> > > >> >> > acpi_os_execute calls callback asynchronously later? Or what exactly do it? > >> >> > >> >> In this case, it adds the callback to the kacpi_notify_wq workqueue > >> >> for deferred execution. > >> > > >> > +Rafael for context/advice on the use of acpi_os_execute here. > >> > > >> > This is true, but a quick scan through that call path doesn't tell me why we > >> > would need to call it here instead of just setting rbtn_data->suspended = false. > >> > The comment suggests waiting for the event, but is that what this is doing? It > >> > appears to me to be immediately scheduling the function to a work queue, not > >> > waiting for the event notifier. > >> > > >> > Also, since there is no indication to the user that a failure occurs, this > >> > function is basically equivalent in the success and failure case (the success > >> > case is just slower). > >> > > >> > Am I missing something critical here? > >> > >> Maybe saying that we are waiting for the extra event is not really > >> correct. Since the extra ACPI notification is processed by means > >> of kacpi_notify_wq, or at least that's my understanding, our callback > >> is likely going to be executed after we received the extra ACPI > >> notification. This was suggested by Rafael [2]. > > > > I see, the workqueue is run after the event is issued. If that's the case, how > > are we ensured that it will get cleared? Isn't it only some systems that have > > this problem? > > > > What happens to the systems that do not send this event at resume? Does the > > suspended flag remain set? > > The callback should be executed as long as acpi_os_execute doesn't > return an error. If the BIOS doesn't send the extra notification, > we uselessly wait for whatever was queued before our callback. > > On my laptop, the interval between the call to acpi_os_execute and > the callback execution is ~200ms (rough existimation using a couple > of printks), so not really noticeable. It might be more on some other > systems, but I doubt anyone would notice. And what triggers the callback then? Some unrelated event triggering the workqueue I presume? I don't care to tie the masking of these events to unrelated ones. What guarantee do we have that they will fire? Is it possible for that workqueue to be otherwise empty and not get triggered, effectively disabling our events? > > >> > >> The problem with setting the flag directly from the resume callback > >> is that the extra notification might arrive after we cleared the > >> flag, causing spurious input events [1]. > >> > >> [1] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8001 > >> [2] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8201 > >>
2016-03-29 7:24 GMT+02:00 Darren Hart <dvhart@infradead.org>: > > On Mon, Mar 28, 2016 at 09:41:09PM +0200, Gabriele Mazzotta wrote: > > 2016-03-28 20:56 GMT+02:00 Darren Hart <dvhart@infradead.org>: > > > On Mon, Mar 28, 2016 at 07:58:09PM +0200, Gabriele Mazzotta wrote: > > >> 2016-03-28 19:33 GMT+02:00 Darren Hart <dvhart@infradead.org>: > > >> > On Thu, Mar 24, 2016 at 12:24:56PM +0100, Gabriele Mazzotta wrote: > > >> >> 2016-03-24 10:39 GMT+01:00 Pali Rohár <pali.rohar@gmail.com>: > > >> >> > On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote: > > >> >> >> 2016-03-21 13:17 GMT+01:00 Pali Rohár <pali.rohar@gmail.com>: > > >> >> >> > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote: > > >> >> >> >> +#ifdef CONFIG_PM_SLEEP > > >> >> >> >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context) > > >> >> >> >> +{ > > >> >> >> >> + struct rbtn_data *rbtn_data = context; > > >> >> >> >> + > > >> >> >> >> + rbtn_data->suspended = false; > > >> >> >> >> +} > > >> >> >> >> + > > >> >> >> >> +static int rbtn_suspend(struct device *dev) > > >> >> >> >> +{ > > >> >> >> >> + struct acpi_device *device = to_acpi_device(dev); > > >> >> >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device); > > >> >> >> >> + > > >> >> >> >> + rbtn_data->suspended = true; > > >> >> >> >> + > > >> >> >> >> + return 0; > > >> >> >> >> +} > > >> >> >> >> + > > >> >> >> >> +static int rbtn_resume(struct device *dev) > > >> >> >> >> +{ > > >> >> >> >> + struct acpi_device *device = to_acpi_device(dev); > > >> >> >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device); > > >> >> >> >> + acpi_status status; > > >> >> >> >> + > > >> >> >> >> + /* > > >> >> >> >> + * Clear the flag only after we received the extra > > >> >> >> >> + * ACPI notification. > > >> >> >> >> + */ > > >> >> >> >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER, > > >> >> >> >> + rbtn_acpi_clear_flag, rbtn_data); > > >> >> >> >> + if (ACPI_FAILURE(status)) > > >> >> >> >> + rbtn_data->suspended = false; > > >> >> >> > > > >> >> >> > I case when acpi_os_execute success it calls rbtn_acpi_clear_flag, > > >> >> >> > right? And that will set suspended to false. When acpi_os_execute fails, > > >> >> >> > then it set suspended too to false... Then whole acpi_os_execute doing > > >> >> >> > just "barrier" after which suspended flag can be set to false. So I > > >> >> >> > think rbtn_acpi_clear_flag function is not needed here. > > >> >> >> > > > >> >> >> > Cannot you pass NULL or empty function pointer as callback? Or what was > > >> >> >> > reason to do that flag clearing at "two places"? > > >> >> >> > > >> >> >> acpi_os_execute doesn't wait for the callback to be executed, so > > >> >> >> I can't clear the flag from rbtn_resume. > > >> >> > > > >> >> > acpi_os_execute calls callback asynchronously later? Or what exactly do it? > > >> >> > > >> >> In this case, it adds the callback to the kacpi_notify_wq workqueue > > >> >> for deferred execution. > > >> > > > >> > +Rafael for context/advice on the use of acpi_os_execute here. > > >> > > > >> > This is true, but a quick scan through that call path doesn't tell me why we > > >> > would need to call it here instead of just setting rbtn_data->suspended = false. > > >> > The comment suggests waiting for the event, but is that what this is doing? It > > >> > appears to me to be immediately scheduling the function to a work queue, not > > >> > waiting for the event notifier. > > >> > > > >> > Also, since there is no indication to the user that a failure occurs, this > > >> > function is basically equivalent in the success and failure case (the success > > >> > case is just slower). > > >> > > > >> > Am I missing something critical here? > > >> > > >> Maybe saying that we are waiting for the extra event is not really > > >> correct. Since the extra ACPI notification is processed by means > > >> of kacpi_notify_wq, or at least that's my understanding, our callback > > >> is likely going to be executed after we received the extra ACPI > > >> notification. This was suggested by Rafael [2]. > > > > > > I see, the workqueue is run after the event is issued. If that's the case, how > > > are we ensured that it will get cleared? Isn't it only some systems that have > > > this problem? > > > > > > What happens to the systems that do not send this event at resume? Does the > > > suspended flag remain set? > > > > The callback should be executed as long as acpi_os_execute doesn't > > return an error. If the BIOS doesn't send the extra notification, > > we uselessly wait for whatever was queued before our callback. > > > > On my laptop, the interval between the call to acpi_os_execute and > > the callback execution is ~200ms (rough existimation using a couple > > of printks), so not really noticeable. It might be more on some other > > systems, but I doubt anyone would notice. > > And what triggers the callback then? Some unrelated event triggering the > workqueue I presume? I don't care to tie the masking of these events to > unrelated ones. What guarantee do we have that they will fire? Is it possible > for that workqueue to be otherwise empty and not get triggered, effectively > disabling our events? acpi_os_execute creates a work item for the callback and adds it to the kacpi_notify_wq workqueue. Nothing triggers it, it just waits for its turn. The BIOS sends the notification immediately at resume, so the work item that handles it is likely going to get queued before our work item. In my case, the notification is handled even before dell-rbtn is resumed (and that's why the original worked fine for me). > > > > >> > > >> The problem with setting the flag directly from the resume callback > > >> is that the extra notification might arrive after we cleared the > > >> flag, causing spurious input events [1]. > > >> > > >> [1] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8001 > > >> [2] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8201 > > >> > > -- > Darren Hart > Intel Open Source Technology Center -- To unsubscribe from this list: send the line "unsubscribe platform-driver-x86" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Monday, March 28, 2016 10:33:09 AM Darren Hart wrote: > On Thu, Mar 24, 2016 at 12:24:56PM +0100, Gabriele Mazzotta wrote: > > 2016-03-24 10:39 GMT+01:00 Pali Rohár <pali.rohar@gmail.com>: > > > On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote: > > >> 2016-03-21 13:17 GMT+01:00 Pali Rohár <pali.rohar@gmail.com>: > > >> > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote: > > >> >> +#ifdef CONFIG_PM_SLEEP > > >> >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context) > > >> >> +{ > > >> >> + struct rbtn_data *rbtn_data = context; > > >> >> + > > >> >> + rbtn_data->suspended = false; > > >> >> +} > > >> >> + > > >> >> +static int rbtn_suspend(struct device *dev) > > >> >> +{ > > >> >> + struct acpi_device *device = to_acpi_device(dev); > > >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device); > > >> >> + > > >> >> + rbtn_data->suspended = true; > > >> >> + > > >> >> + return 0; > > >> >> +} > > >> >> + > > >> >> +static int rbtn_resume(struct device *dev) > > >> >> +{ > > >> >> + struct acpi_device *device = to_acpi_device(dev); > > >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device); > > >> >> + acpi_status status; > > >> >> + > > >> >> + /* > > >> >> + * Clear the flag only after we received the extra > > >> >> + * ACPI notification. > > >> >> + */ > > >> >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER, > > >> >> + rbtn_acpi_clear_flag, rbtn_data); > > >> >> + if (ACPI_FAILURE(status)) > > >> >> + rbtn_data->suspended = false; > > >> > > > >> > I case when acpi_os_execute success it calls rbtn_acpi_clear_flag, > > >> > right? And that will set suspended to false. When acpi_os_execute fails, > > >> > then it set suspended too to false... Then whole acpi_os_execute doing > > >> > just "barrier" after which suspended flag can be set to false. So I > > >> > think rbtn_acpi_clear_flag function is not needed here. > > >> > > > >> > Cannot you pass NULL or empty function pointer as callback? Or what was > > >> > reason to do that flag clearing at "two places"? > > >> > > >> acpi_os_execute doesn't wait for the callback to be executed, so > > >> I can't clear the flag from rbtn_resume. > > > > > > acpi_os_execute calls callback asynchronously later? Or what exactly do it? > > > > In this case, it adds the callback to the kacpi_notify_wq workqueue > > for deferred execution. > > +Rafael for context/advice on the use of acpi_os_execute here. > > This is true, but a quick scan through that call path doesn't tell me why we > would need to call it here instead of just setting rbtn_data->suspended = false. > The comment suggests waiting for the event, but is that what this is doing? It > appears to me to be immediately scheduling the function to a work queue, not > waiting for the event notifier. I think this is supposed to work as a barrier. That is, it will only run after all events in the queue have been processed. I'm not sure if that's necessary, though. Thanks, Rafael -- To unsubscribe from this list: send the line "unsubscribe platform-driver-x86" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tuesday 29 March 2016 15:11:35 Rafael J. Wysocki wrote: > On Monday, March 28, 2016 10:33:09 AM Darren Hart wrote: > > On Thu, Mar 24, 2016 at 12:24:56PM +0100, Gabriele Mazzotta wrote: > > > 2016-03-24 10:39 GMT+01:00 Pali Rohár <pali.rohar@gmail.com>: > > > > On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote: > > > >> 2016-03-21 13:17 GMT+01:00 Pali Rohár <pali.rohar@gmail.com>: > > > >> > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote: > > > >> >> +#ifdef CONFIG_PM_SLEEP > > > >> >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context) > > > >> >> +{ > > > >> >> + struct rbtn_data *rbtn_data = context; > > > >> >> + > > > >> >> + rbtn_data->suspended = false; > > > >> >> +} > > > >> >> + > > > >> >> +static int rbtn_suspend(struct device *dev) > > > >> >> +{ > > > >> >> + struct acpi_device *device = to_acpi_device(dev); > > > >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device); > > > >> >> + > > > >> >> + rbtn_data->suspended = true; > > > >> >> + > > > >> >> + return 0; > > > >> >> +} > > > >> >> + > > > >> >> +static int rbtn_resume(struct device *dev) > > > >> >> +{ > > > >> >> + struct acpi_device *device = to_acpi_device(dev); > > > >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device); > > > >> >> + acpi_status status; > > > >> >> + > > > >> >> + /* > > > >> >> + * Clear the flag only after we received the extra > > > >> >> + * ACPI notification. > > > >> >> + */ > > > >> >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER, > > > >> >> + rbtn_acpi_clear_flag, rbtn_data); > > > >> >> + if (ACPI_FAILURE(status)) > > > >> >> + rbtn_data->suspended = false; > > > >> > > > > >> > I case when acpi_os_execute success it calls rbtn_acpi_clear_flag, > > > >> > right? And that will set suspended to false. When acpi_os_execute fails, > > > >> > then it set suspended too to false... Then whole acpi_os_execute doing > > > >> > just "barrier" after which suspended flag can be set to false. So I > > > >> > think rbtn_acpi_clear_flag function is not needed here. > > > >> > > > > >> > Cannot you pass NULL or empty function pointer as callback? Or what was > > > >> > reason to do that flag clearing at "two places"? > > > >> > > > >> acpi_os_execute doesn't wait for the callback to be executed, so > > > >> I can't clear the flag from rbtn_resume. > > > > > > > > acpi_os_execute calls callback asynchronously later? Or what exactly do it? > > > > > > In this case, it adds the callback to the kacpi_notify_wq workqueue > > > for deferred execution. > > > > +Rafael for context/advice on the use of acpi_os_execute here. > > > > This is true, but a quick scan through that call path doesn't tell me why we > > would need to call it here instead of just setting rbtn_data->suspended = false. > > The comment suggests waiting for the event, but is that what this is doing? It > > appears to me to be immediately scheduling the function to a work queue, not > > waiting for the event notifier. > > I think this is supposed to work as a barrier. That is, it will only run after > all events in the queue have been processed. > > I'm not sure if that's necessary, though. > > Thanks, > Rafael > Darren, Gabriele, what is state of this patch? Bug is not still fixed, right?
2016-04-18 14:35 GMT+02:00 Pali Rohár <pali.rohar@gmail.com>: > On Tuesday 29 March 2016 15:11:35 Rafael J. Wysocki wrote: >> On Monday, March 28, 2016 10:33:09 AM Darren Hart wrote: >> > On Thu, Mar 24, 2016 at 12:24:56PM +0100, Gabriele Mazzotta wrote: >> > > 2016-03-24 10:39 GMT+01:00 Pali Rohár <pali.rohar@gmail.com>: >> > > > On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote: >> > > >> 2016-03-21 13:17 GMT+01:00 Pali Rohár <pali.rohar@gmail.com>: >> > > >> > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote: >> > > >> >> +#ifdef CONFIG_PM_SLEEP >> > > >> >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context) >> > > >> >> +{ >> > > >> >> + struct rbtn_data *rbtn_data = context; >> > > >> >> + >> > > >> >> + rbtn_data->suspended = false; >> > > >> >> +} >> > > >> >> + >> > > >> >> +static int rbtn_suspend(struct device *dev) >> > > >> >> +{ >> > > >> >> + struct acpi_device *device = to_acpi_device(dev); >> > > >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device); >> > > >> >> + >> > > >> >> + rbtn_data->suspended = true; >> > > >> >> + >> > > >> >> + return 0; >> > > >> >> +} >> > > >> >> + >> > > >> >> +static int rbtn_resume(struct device *dev) >> > > >> >> +{ >> > > >> >> + struct acpi_device *device = to_acpi_device(dev); >> > > >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device); >> > > >> >> + acpi_status status; >> > > >> >> + >> > > >> >> + /* >> > > >> >> + * Clear the flag only after we received the extra >> > > >> >> + * ACPI notification. >> > > >> >> + */ >> > > >> >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER, >> > > >> >> + rbtn_acpi_clear_flag, rbtn_data); >> > > >> >> + if (ACPI_FAILURE(status)) >> > > >> >> + rbtn_data->suspended = false; >> > > >> > >> > > >> > I case when acpi_os_execute success it calls rbtn_acpi_clear_flag, >> > > >> > right? And that will set suspended to false. When acpi_os_execute fails, >> > > >> > then it set suspended too to false... Then whole acpi_os_execute doing >> > > >> > just "barrier" after which suspended flag can be set to false. So I >> > > >> > think rbtn_acpi_clear_flag function is not needed here. >> > > >> > >> > > >> > Cannot you pass NULL or empty function pointer as callback? Or what was >> > > >> > reason to do that flag clearing at "two places"? >> > > >> >> > > >> acpi_os_execute doesn't wait for the callback to be executed, so >> > > >> I can't clear the flag from rbtn_resume. >> > > > >> > > > acpi_os_execute calls callback asynchronously later? Or what exactly do it? >> > > >> > > In this case, it adds the callback to the kacpi_notify_wq workqueue >> > > for deferred execution. >> > >> > +Rafael for context/advice on the use of acpi_os_execute here. >> > >> > This is true, but a quick scan through that call path doesn't tell me why we >> > would need to call it here instead of just setting rbtn_data->suspended = false. >> > The comment suggests waiting for the event, but is that what this is doing? It >> > appears to me to be immediately scheduling the function to a work queue, not >> > waiting for the event notifier. >> >> I think this is supposed to work as a barrier. That is, it will only run after >> all events in the queue have been processed. >> >> I'm not sure if that's necessary, though. >> >> Thanks, >> Rafael >> > > Darren, Gabriele, what is state of this patch? Bug is not still fixed, > right? Yes, the bug is still there and this patch fixes it. Just to make it clear, we need the barrier. Andrei could reproduce the bug without it [1], but not with it, as he confirmed in this thread [2]. [1] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8001 [2] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8937 > -- > Pali Rohár > pali.rohar@gmail.com -- To unsubscribe from this list: send the line "unsubscribe platform-driver-x86" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Monday 25 April 2016 22:06:11 Gabriele Mazzotta wrote: > 2016-04-18 14:35 GMT+02:00 Pali Rohár <pali.rohar@gmail.com>: > > On Tuesday 29 March 2016 15:11:35 Rafael J. Wysocki wrote: > >> On Monday, March 28, 2016 10:33:09 AM Darren Hart wrote: > >> > On Thu, Mar 24, 2016 at 12:24:56PM +0100, Gabriele Mazzotta wrote: > >> > > 2016-03-24 10:39 GMT+01:00 Pali Rohár <pali.rohar@gmail.com>: > >> > > > On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote: > >> > > >> 2016-03-21 13:17 GMT+01:00 Pali Rohár <pali.rohar@gmail.com>: > >> > > >> > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote: > >> > > >> >> +#ifdef CONFIG_PM_SLEEP > >> > > >> >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context) > >> > > >> >> +{ > >> > > >> >> + struct rbtn_data *rbtn_data = context; > >> > > >> >> + > >> > > >> >> + rbtn_data->suspended = false; > >> > > >> >> +} > >> > > >> >> + > >> > > >> >> +static int rbtn_suspend(struct device *dev) > >> > > >> >> +{ > >> > > >> >> + struct acpi_device *device = to_acpi_device(dev); > >> > > >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device); > >> > > >> >> + > >> > > >> >> + rbtn_data->suspended = true; > >> > > >> >> + > >> > > >> >> + return 0; > >> > > >> >> +} > >> > > >> >> + > >> > > >> >> +static int rbtn_resume(struct device *dev) > >> > > >> >> +{ > >> > > >> >> + struct acpi_device *device = to_acpi_device(dev); > >> > > >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device); > >> > > >> >> + acpi_status status; > >> > > >> >> + > >> > > >> >> + /* > >> > > >> >> + * Clear the flag only after we received the extra > >> > > >> >> + * ACPI notification. > >> > > >> >> + */ > >> > > >> >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER, > >> > > >> >> + rbtn_acpi_clear_flag, rbtn_data); > >> > > >> >> + if (ACPI_FAILURE(status)) > >> > > >> >> + rbtn_data->suspended = false; > >> > > >> > > >> > > >> > I case when acpi_os_execute success it calls rbtn_acpi_clear_flag, > >> > > >> > right? And that will set suspended to false. When acpi_os_execute fails, > >> > > >> > then it set suspended too to false... Then whole acpi_os_execute doing > >> > > >> > just "barrier" after which suspended flag can be set to false. So I > >> > > >> > think rbtn_acpi_clear_flag function is not needed here. > >> > > >> > > >> > > >> > Cannot you pass NULL or empty function pointer as callback? Or what was > >> > > >> > reason to do that flag clearing at "two places"? > >> > > >> > >> > > >> acpi_os_execute doesn't wait for the callback to be executed, so > >> > > >> I can't clear the flag from rbtn_resume. > >> > > > > >> > > > acpi_os_execute calls callback asynchronously later? Or what exactly do it? > >> > > > >> > > In this case, it adds the callback to the kacpi_notify_wq workqueue > >> > > for deferred execution. > >> > > >> > +Rafael for context/advice on the use of acpi_os_execute here. > >> > > >> > This is true, but a quick scan through that call path doesn't tell me why we > >> > would need to call it here instead of just setting rbtn_data->suspended = false. > >> > The comment suggests waiting for the event, but is that what this is doing? It > >> > appears to me to be immediately scheduling the function to a work queue, not > >> > waiting for the event notifier. > >> > >> I think this is supposed to work as a barrier. That is, it will only run after > >> all events in the queue have been processed. > >> > >> I'm not sure if that's necessary, though. > >> > >> Thanks, > >> Rafael > >> > > > > Darren, Gabriele, what is state of this patch? Bug is not still fixed, > > right? > > Yes, the bug is still there and this patch fixes it. > > Just to make it clear, we need the barrier. Andrei could reproduce > the bug without it [1], but not with it, as he confirmed in this > thread [2]. > > [1] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8001 > [2] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8937 Ok, so it means that somebody (who understand ACPI) should review code and accept it or show what is needed to fix. Plus maybe adds more comments how that "barrier" works as I was first confused... Darren, Rafael, can you do review of this patch?
On Thu, May 19, 2016 at 03:30:32PM +0200, Pali Rohár wrote: > On Monday 25 April 2016 22:06:11 Gabriele Mazzotta wrote: > > 2016-04-18 14:35 GMT+02:00 Pali Rohár <pali.rohar@gmail.com>: > > > On Tuesday 29 March 2016 15:11:35 Rafael J. Wysocki wrote: > > >> On Monday, March 28, 2016 10:33:09 AM Darren Hart wrote: > > >> > On Thu, Mar 24, 2016 at 12:24:56PM +0100, Gabriele Mazzotta wrote: > > >> > > 2016-03-24 10:39 GMT+01:00 Pali Rohár <pali.rohar@gmail.com>: > > >> > > > On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote: > > >> > > >> 2016-03-21 13:17 GMT+01:00 Pali Rohár <pali.rohar@gmail.com>: > > >> > > >> > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote: > > >> > > >> >> +#ifdef CONFIG_PM_SLEEP > > >> > > >> >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context) > > >> > > >> >> +{ > > >> > > >> >> + struct rbtn_data *rbtn_data = context; > > >> > > >> >> + > > >> > > >> >> + rbtn_data->suspended = false; > > >> > > >> >> +} > > >> > > >> >> + > > >> > > >> >> +static int rbtn_suspend(struct device *dev) > > >> > > >> >> +{ > > >> > > >> >> + struct acpi_device *device = to_acpi_device(dev); > > >> > > >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device); > > >> > > >> >> + > > >> > > >> >> + rbtn_data->suspended = true; > > >> > > >> >> + > > >> > > >> >> + return 0; > > >> > > >> >> +} > > >> > > >> >> + > > >> > > >> >> +static int rbtn_resume(struct device *dev) > > >> > > >> >> +{ > > >> > > >> >> + struct acpi_device *device = to_acpi_device(dev); > > >> > > >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device); > > >> > > >> >> + acpi_status status; > > >> > > >> >> + > > >> > > >> >> + /* > > >> > > >> >> + * Clear the flag only after we received the extra > > >> > > >> >> + * ACPI notification. > > >> > > >> >> + */ > > >> > > >> >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER, > > >> > > >> >> + rbtn_acpi_clear_flag, rbtn_data); > > >> > > >> >> + if (ACPI_FAILURE(status)) > > >> > > >> >> + rbtn_data->suspended = false; > > >> > > >> > > > >> > > >> > I case when acpi_os_execute success it calls rbtn_acpi_clear_flag, > > >> > > >> > right? And that will set suspended to false. When acpi_os_execute fails, > > >> > > >> > then it set suspended too to false... Then whole acpi_os_execute doing > > >> > > >> > just "barrier" after which suspended flag can be set to false. So I > > >> > > >> > think rbtn_acpi_clear_flag function is not needed here. > > >> > > >> > > > >> > > >> > Cannot you pass NULL or empty function pointer as callback? Or what was > > >> > > >> > reason to do that flag clearing at "two places"? > > >> > > >> > > >> > > >> acpi_os_execute doesn't wait for the callback to be executed, so > > >> > > >> I can't clear the flag from rbtn_resume. > > >> > > > > > >> > > > acpi_os_execute calls callback asynchronously later? Or what exactly do it? > > >> > > > > >> > > In this case, it adds the callback to the kacpi_notify_wq workqueue > > >> > > for deferred execution. > > >> > > > >> > +Rafael for context/advice on the use of acpi_os_execute here. > > >> > > > >> > This is true, but a quick scan through that call path doesn't tell me why we > > >> > would need to call it here instead of just setting rbtn_data->suspended = false. > > >> > The comment suggests waiting for the event, but is that what this is doing? It > > >> > appears to me to be immediately scheduling the function to a work queue, not > > >> > waiting for the event notifier. > > >> > > >> I think this is supposed to work as a barrier. That is, it will only run after > > >> all events in the queue have been processed. > > >> > > >> I'm not sure if that's necessary, though. > > >> > > >> Thanks, > > >> Rafael > > >> > > > > > > Darren, Gabriele, what is state of this patch? Bug is not still fixed, > > > right? > > > > Yes, the bug is still there and this patch fixes it. > > > > Just to make it clear, we need the barrier. Andrei could reproduce > > the bug without it [1], but not with it, as he confirmed in this > > thread [2]. > > > > [1] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8001 > > [2] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8937 > > Ok, so it means that somebody (who understand ACPI) should review code > and accept it or show what is needed to fix. Plus maybe adds more > comments how that "barrier" works as I was first confused... > > Darren, Rafael, can you do review of this patch? > Yes, working toward it.
On Thu, May 19, 2016 at 03:30:32PM +0200, Pali Rohár wrote: > On Monday 25 April 2016 22:06:11 Gabriele Mazzotta wrote: > > 2016-04-18 14:35 GMT+02:00 Pali Rohár <pali.rohar@gmail.com>: > > > On Tuesday 29 March 2016 15:11:35 Rafael J. Wysocki wrote: > > >> On Monday, March 28, 2016 10:33:09 AM Darren Hart wrote: > > >> > On Thu, Mar 24, 2016 at 12:24:56PM +0100, Gabriele Mazzotta wrote: > > >> > > 2016-03-24 10:39 GMT+01:00 Pali Rohár <pali.rohar@gmail.com>: > > >> > > > On Monday 21 March 2016 16:13:34 Gabriele Mazzotta wrote: > > >> > > >> 2016-03-21 13:17 GMT+01:00 Pali Rohár <pali.rohar@gmail.com>: > > >> > > >> > On Friday 18 March 2016 23:44:23 Gabriele Mazzotta wrote: > > >> > > >> >> +#ifdef CONFIG_PM_SLEEP > > >> > > >> >> +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context) > > >> > > >> >> +{ > > >> > > >> >> + struct rbtn_data *rbtn_data = context; > > >> > > >> >> + > > >> > > >> >> + rbtn_data->suspended = false; > > >> > > >> >> +} > > >> > > >> >> + > > >> > > >> >> +static int rbtn_suspend(struct device *dev) > > >> > > >> >> +{ > > >> > > >> >> + struct acpi_device *device = to_acpi_device(dev); > > >> > > >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device); > > >> > > >> >> + > > >> > > >> >> + rbtn_data->suspended = true; > > >> > > >> >> + > > >> > > >> >> + return 0; > > >> > > >> >> +} > > >> > > >> >> + > > >> > > >> >> +static int rbtn_resume(struct device *dev) > > >> > > >> >> +{ > > >> > > >> >> + struct acpi_device *device = to_acpi_device(dev); > > >> > > >> >> + struct rbtn_data *rbtn_data = acpi_driver_data(device); > > >> > > >> >> + acpi_status status; > > >> > > >> >> + > > >> > > >> >> + /* > > >> > > >> >> + * Clear the flag only after we received the extra > > >> > > >> >> + * ACPI notification. > > >> > > >> >> + */ > > >> > > >> >> + status = acpi_os_execute(OSL_NOTIFY_HANDLER, > > >> > > >> >> + rbtn_acpi_clear_flag, rbtn_data); > > >> > > >> >> + if (ACPI_FAILURE(status)) > > >> > > >> >> + rbtn_data->suspended = false; > > >> > > >> > > > >> > > >> > I case when acpi_os_execute success it calls rbtn_acpi_clear_flag, > > >> > > >> > right? And that will set suspended to false. When acpi_os_execute fails, > > >> > > >> > then it set suspended too to false... Then whole acpi_os_execute doing > > >> > > >> > just "barrier" after which suspended flag can be set to false. So I > > >> > > >> > think rbtn_acpi_clear_flag function is not needed here. > > >> > > >> > > > >> > > >> > Cannot you pass NULL or empty function pointer as callback? Or what was > > >> > > >> > reason to do that flag clearing at "two places"? > > >> > > >> > > >> > > >> acpi_os_execute doesn't wait for the callback to be executed, so > > >> > > >> I can't clear the flag from rbtn_resume. > > >> > > > > > >> > > > acpi_os_execute calls callback asynchronously later? Or what exactly do it? > > >> > > > > >> > > In this case, it adds the callback to the kacpi_notify_wq workqueue > > >> > > for deferred execution. > > >> > > > >> > +Rafael for context/advice on the use of acpi_os_execute here. > > >> > > > >> > This is true, but a quick scan through that call path doesn't tell me why we > > >> > would need to call it here instead of just setting rbtn_data->suspended = false. > > >> > The comment suggests waiting for the event, but is that what this is doing? It > > >> > appears to me to be immediately scheduling the function to a work queue, not > > >> > waiting for the event notifier. > > >> > > >> I think this is supposed to work as a barrier. That is, it will only run after > > >> all events in the queue have been processed. > > >> > > >> I'm not sure if that's necessary, though. > > >> > > >> Thanks, > > >> Rafael > > >> > > > > > > Darren, Gabriele, what is state of this patch? Bug is not still fixed, > > > right? > > > > Yes, the bug is still there and this patch fixes it. > > > > Just to make it clear, we need the barrier. Andrei could reproduce > > the bug without it [1], but not with it, as he confirmed in this > > thread [2]. > > > > [1] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8001 > > [2] http://article.gmane.org/gmane.linux.drivers.platform.x86.devel/8937 > > Ok, so it means that somebody (who understand ACPI) should review code > and accept it or show what is needed to fix. Plus maybe adds more > comments how that "barrier" works as I was first confused... > > Darren, Rafael, can you do review of this patch? > Pali and Gabriele have responded to all questions raised. I have some reservations that this solution is still a bit racy, but it does fix the problem for the affected users. I've queued this. Thanks for your patience.
On Monday 23 May 2016 23:26:55 Darren Hart wrote:
> I've queued this. Thanks for your patience.
Ok, In that case I would update comments in patch to try it more clear
what code is doing.
On Tue, May 24, 2016 at 12:06:03AM +0200, Pali Rohár wrote: > On Monday 23 May 2016 23:26:55 Darren Hart wrote: > > I've queued this. Thanks for your patience. > > Ok, In that case I would update comments in patch to try it more clear > what code is doing. I thought I had your approval on this one Pali. Apologies if that was not the case. Did I miss a change request from you? If so, please point me at it, and I'll dequeue this one and wait for an updated one.
On Tuesday 24 May 2016 00:17:15 Darren Hart wrote: > On Tue, May 24, 2016 at 12:06:03AM +0200, Pali Rohár wrote: > > On Monday 23 May 2016 23:26:55 Darren Hart wrote: > > > I've queued this. Thanks for your patience. > > > > Ok, In that case I would update comments in patch to try it more > > clear what code is doing. > > I thought I had your approval on this one Pali. Apologies if that was > not the case. Did I miss a change request from you? > > If so, please point me at it, and I'll dequeue this one and wait for > an updated one. I just wanted to review that code from somebody else and decide if accept it or not. Because I was not sure if it is OK... But there was no objection, so patch is OK. And I pointed that patch could have better comments to describe what it is doing as at first time I was confused. So I believe that you can update patch in your queue with new version which just change comments in source code (without functional changes).
diff --git a/drivers/platform/x86/dell-rbtn.c b/drivers/platform/x86/dell-rbtn.c index 5155278..b144b8c 100644 --- a/drivers/platform/x86/dell-rbtn.c +++ b/drivers/platform/x86/dell-rbtn.c @@ -28,6 +28,7 @@ struct rbtn_data { enum rbtn_type type; struct rfkill *rfkill; struct input_dev *input_dev; + bool suspended; }; @@ -220,9 +221,49 @@ static const struct acpi_device_id rbtn_ids[] = { { "", 0 }, }; +#ifdef CONFIG_PM_SLEEP +static void ACPI_SYSTEM_XFACE rbtn_acpi_clear_flag(void *context) +{ + struct rbtn_data *rbtn_data = context; + + rbtn_data->suspended = false; +} + +static int rbtn_suspend(struct device *dev) +{ + struct acpi_device *device = to_acpi_device(dev); + struct rbtn_data *rbtn_data = acpi_driver_data(device); + + rbtn_data->suspended = true; + + return 0; +} + +static int rbtn_resume(struct device *dev) +{ + struct acpi_device *device = to_acpi_device(dev); + struct rbtn_data *rbtn_data = acpi_driver_data(device); + acpi_status status; + + /* + * Clear the flag only after we received the extra + * ACPI notification. + */ + status = acpi_os_execute(OSL_NOTIFY_HANDLER, + rbtn_acpi_clear_flag, rbtn_data); + if (ACPI_FAILURE(status)) + rbtn_data->suspended = false; + + return 0; +} +#endif + +static SIMPLE_DEV_PM_OPS(rbtn_pm_ops, rbtn_suspend, rbtn_resume); + static struct acpi_driver rbtn_driver = { .name = "dell-rbtn", .ids = rbtn_ids, + .drv.pm = &rbtn_pm_ops, .ops = { .add = rbtn_add, .remove = rbtn_remove, @@ -384,6 +425,15 @@ static void rbtn_notify(struct acpi_device *device, u32 event) { struct rbtn_data *rbtn_data = device->driver_data; + /* + * Some BIOSes send autonomously a notification at resume. + * Ignore it to prevent unwanted input events. + */ + if (rbtn_data->suspended) { + dev_dbg(&device->dev, "ACPI notification ignored\n"); + return; + } + if (event != 0x80) { dev_info(&device->dev, "Received unknown event (0x%x)\n", event);
Some BIOSes unconditionally send an ACPI notification to RBTN when the system is resuming from suspend. This makes dell-rbtn send an input event to userspace as if a function key was pressed. Prevent this by ignoring all the notifications received while the device is suspended. Link: https://bugzilla.kernel.org/show_bug.cgi?id=106031 Signed-off-by: Gabriele Mazzotta <gabriele.mzt@gmail.com> --- Same as v2 with some comments drivers/platform/x86/dell-rbtn.c | 50 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 50 insertions(+)