| Message ID | 20200508162937.2566818-1-bryan.odonoghue@linaro.org (mailing list archive) |
|---|---|
| State | Mainlined |
| Commit | 3e63cff384e625f09758ce8f4d01ae3033402b63 |
| Headers | show |
| Series | usb: roles: Switch on role-switch uevent reporting | expand |
在 2020/5/9 上午12:29, Bryan O'Donoghue 写道: > Right now we don't report to user-space a role switch when doing a > usb_role_switch_set_role() despite having registered the uevent callbacks. > > This patch switches on the notifications allowing user-space to see > role-switch change notifications and subsequently determine the current > controller data-role. > > example: > PFX=/devices/platform/soc/78d9000.usb/ci_hdrc.0 > > root@somebox# udevadm monitor -p > > KERNEL[49.894994] change $PFX/usb_role/ci_hdrc.0-role-switch (usb_role) > ACTION=change > DEVPATH=$PFX/usb_role/ci_hdrc.0-role-switch > SUBSYSTEM=usb_role > DEVTYPE=usb_role_switch > USB_ROLE_SWITCH=ci_hdrc.0-role-switch > SEQNUM=2432 > > Cc: Heikki Krogerus <heikki.krogerus@linux.intel.com> > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > Cc: Chunfeng Yun <chunfeng.yun@mediatek.com> > Cc: Suzuki K Poulose <suzuki.poulose@arm.com> > Cc: Alexandre Belloni <alexandre.belloni@bootlin.com> > Cc: Wen Yang <wenyang@linux.alibaba.com> > Cc: chenqiwu <chenqiwu@xiaomi.com> > Cc: linux-kernel@vger.kernel.org > Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org> > --- > drivers/usb/roles/class.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/drivers/usb/roles/class.c b/drivers/usb/roles/class.c > index 5b17709821df..27d92af29635 100644 > --- a/drivers/usb/roles/class.c > +++ b/drivers/usb/roles/class.c > @@ -49,8 +49,10 @@ int usb_role_switch_set_role(struct usb_role_switch *sw, enum usb_role role) > mutex_lock(&sw->lock); > > ret = sw->set(sw, role); > - if (!ret) > + if (!ret) { > sw->role = role; > + kobject_uevent(&sw->dev.kobj, KOBJ_CHANGE); > + } > > mutex_unlock(&sw->lock); > > Hi, we may also need to deal with the return value of kobject_uevent(). Should we move it under the line mutex_unlock(&sw->lock)? Regards, Wen
On 09/05/2020 04:24, Wen Yang wrote: > > > 在 2020/5/9 上午12:29, Bryan O'Donoghue 写道: >> Right now we don't report to user-space a role switch when doing a >> usb_role_switch_set_role() despite having registered the uevent >> callbacks. >> >> This patch switches on the notifications allowing user-space to see >> role-switch change notifications and subsequently determine the current >> controller data-role. >> >> example: >> PFX=/devices/platform/soc/78d9000.usb/ci_hdrc.0 >> >> root@somebox# udevadm monitor -p >> >> KERNEL[49.894994] change $PFX/usb_role/ci_hdrc.0-role-switch (usb_role) >> ACTION=change >> DEVPATH=$PFX/usb_role/ci_hdrc.0-role-switch >> SUBSYSTEM=usb_role >> DEVTYPE=usb_role_switch >> USB_ROLE_SWITCH=ci_hdrc.0-role-switch >> SEQNUM=2432 >> >> Cc: Heikki Krogerus <heikki.krogerus@linux.intel.com> >> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> >> Cc: Chunfeng Yun <chunfeng.yun@mediatek.com> >> Cc: Suzuki K Poulose <suzuki.poulose@arm.com> >> Cc: Alexandre Belloni <alexandre.belloni@bootlin.com> >> Cc: Wen Yang <wenyang@linux.alibaba.com> >> Cc: chenqiwu <chenqiwu@xiaomi.com> >> Cc: linux-kernel@vger.kernel.org >> Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org> >> --- >> drivers/usb/roles/class.c | 4 +++- >> 1 file changed, 3 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/usb/roles/class.c b/drivers/usb/roles/class.c >> index 5b17709821df..27d92af29635 100644 >> --- a/drivers/usb/roles/class.c >> +++ b/drivers/usb/roles/class.c >> @@ -49,8 +49,10 @@ int usb_role_switch_set_role(struct usb_role_switch >> *sw, enum usb_role role) >> mutex_lock(&sw->lock); >> ret = sw->set(sw, role); >> - if (!ret) >> + if (!ret) { >> sw->role = role; >> + kobject_uevent(&sw->dev.kobj, KOBJ_CHANGE); >> + } >> mutex_unlock(&sw->lock); >> > > Hi, we may also need to deal with the return value of kobject_uevent(). For an KOBJ_ADD you'd return an error. grep -r "= kobject_uevent(" * drivers/misc/cxl/sysfs.c: rc = kobject_uevent(&cr->kobj, KOBJ_ADD); drivers/uio/uio.c: ret = kobject_uevent(&map->kobj, KOBJ_ADD); drivers/uio/uio.c: ret = kobject_uevent(&portio->kobj, KOBJ_ADD); drivers/visorbus/visorchipset.c: res = kobject_uevent(&chipset_dev->acpi_device->dev.kobj, KOBJ_ONLINE); drivers/visorbus/visorchipset.c: int res = kobject_uevent(&chipset_dev->acpi_device->dev.kobj, For a KOBJ_CHANGE I guess we could print an error if (kobject_uevent(&sw->dev.kobj, KOBJ_CHANGE) dev_err(&sw->dev, "failed to signal USB role-switch uevent\n"); Nobody else seems that bothered about it. grep -r "if (kobject_uevent(" * > Should we move it under the line mutex_unlock(&sw->lock)? I think probably not. the mutex serializes the notification. In theory outside the mutex you could get an out-of-order notification. The main reason I put it where it is, is we already test ret and should only notify the change, when the role-switch has suceeded. As I say, in theory anyway, the mutex enforces the signalling, whatever about the reception, of the role-switch change, so IMO inside the bounds of the mutex is the right place to put it. --- bod
diff --git a/drivers/usb/roles/class.c b/drivers/usb/roles/class.c index 5b17709821df..27d92af29635 100644 --- a/drivers/usb/roles/class.c +++ b/drivers/usb/roles/class.c @@ -49,8 +49,10 @@ int usb_role_switch_set_role(struct usb_role_switch *sw, enum usb_role role) mutex_lock(&sw->lock); ret = sw->set(sw, role); - if (!ret) + if (!ret) { sw->role = role; + kobject_uevent(&sw->dev.kobj, KOBJ_CHANGE); + } mutex_unlock(&sw->lock);
Right now we don't report to user-space a role switch when doing a usb_role_switch_set_role() despite having registered the uevent callbacks. This patch switches on the notifications allowing user-space to see role-switch change notifications and subsequently determine the current controller data-role. example: PFX=/devices/platform/soc/78d9000.usb/ci_hdrc.0 root@somebox# udevadm monitor -p KERNEL[49.894994] change $PFX/usb_role/ci_hdrc.0-role-switch (usb_role) ACTION=change DEVPATH=$PFX/usb_role/ci_hdrc.0-role-switch SUBSYSTEM=usb_role DEVTYPE=usb_role_switch USB_ROLE_SWITCH=ci_hdrc.0-role-switch SEQNUM=2432 Cc: Heikki Krogerus <heikki.krogerus@linux.intel.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Chunfeng Yun <chunfeng.yun@mediatek.com> Cc: Suzuki K Poulose <suzuki.poulose@arm.com> Cc: Alexandre Belloni <alexandre.belloni@bootlin.com> Cc: Wen Yang <wenyang@linux.alibaba.com> Cc: chenqiwu <chenqiwu@xiaomi.com> Cc: linux-kernel@vger.kernel.org Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org> --- drivers/usb/roles/class.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)