| Message ID | 20211028183527.3050-8-semen.protsenko@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | watchdog: s3c2410: Add Exynos850 support | expand |
On 10/28/21 11:35 AM, Sam Protsenko wrote: > When "tmr_atboot" module param is set, the watchdog is started in > driver's probe. In that case, also set WDOG_HW_RUNNING bit to let > watchdog core driver know it's running. This way wathcdog core can kick > the watchdog for us (if CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED option is > enabled), until user space takes control. > > Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org> > --- > drivers/watchdog/s3c2410_wdt.c | 26 +++++++++++++++----------- > 1 file changed, 15 insertions(+), 11 deletions(-) > > diff --git a/drivers/watchdog/s3c2410_wdt.c b/drivers/watchdog/s3c2410_wdt.c > index ca082b1226e3..9af014ff1468 100644 > --- a/drivers/watchdog/s3c2410_wdt.c > +++ b/drivers/watchdog/s3c2410_wdt.c > @@ -732,6 +732,21 @@ static int s3c2410wdt_probe(struct platform_device *pdev) > wdt->wdt_device.bootstatus = s3c2410wdt_get_bootstatus(wdt); > wdt->wdt_device.parent = dev; > > + /* > + * If "tmr_atboot" param is non-zero, start the watchdog right now. Also > + * set WDOG_HW_RUNNING bit, so that watchdog core can kick the watchdog. > + * > + * If we're not enabling the watchdog, then ensure it is disabled if it > + * has been left running from the bootloader or other source. > + */ > + if (tmr_atboot && started == 0) { > + dev_info(dev, "starting watchdog timer\n"); > + s3c2410wdt_start(&wdt->wdt_device); > + set_bit(WDOG_HW_RUNNING, &wdt->wdt_device.status); > + } else if (!tmr_atboot) { > + s3c2410wdt_stop(&wdt->wdt_device); > + } > + This doesn't cover the case where the watchdog is already enabled by the BIOS. In that case, WDOG_HW_RUNNING won't be set, and the watchdog will time out if the userspace handler is not loaded fast enough. The code should consistently set WDOG_HW_RUNNING if the watchdog is running. Guenter > ret = watchdog_register_device(&wdt->wdt_device); > if (ret) > goto err_cpufreq; > @@ -740,17 +755,6 @@ static int s3c2410wdt_probe(struct platform_device *pdev) > if (ret < 0) > goto err_unregister; > > - if (tmr_atboot && started == 0) { > - dev_info(dev, "starting watchdog timer\n"); > - s3c2410wdt_start(&wdt->wdt_device); > - } else if (!tmr_atboot) { > - /* if we're not enabling the watchdog, then ensure it is > - * disabled if it has been left running from the bootloader > - * or other source */ > - > - s3c2410wdt_stop(&wdt->wdt_device); > - } > - > platform_set_drvdata(pdev, wdt); > > /* print out a statement of readiness */ >
On 28/10/2021 20:35, Sam Protsenko wrote: > When "tmr_atboot" module param is set, the watchdog is started in > driver's probe. In that case, also set WDOG_HW_RUNNING bit to let > watchdog core driver know it's running. This way wathcdog core can kick s/wathcdog/watchdog/ > the watchdog for us (if CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED option is > enabled), until user space takes control. This does not explain why you move the code around. I guess you miss here information that we should start the watchdog before registering it? If so please explain why. > > Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org> > --- > drivers/watchdog/s3c2410_wdt.c | 26 +++++++++++++++----------- > 1 file changed, 15 insertions(+), 11 deletions(-) > > diff --git a/drivers/watchdog/s3c2410_wdt.c b/drivers/watchdog/s3c2410_wdt.c > index ca082b1226e3..9af014ff1468 100644 > --- a/drivers/watchdog/s3c2410_wdt.c > +++ b/drivers/watchdog/s3c2410_wdt.c > @@ -732,6 +732,21 @@ static int s3c2410wdt_probe(struct platform_device *pdev) > wdt->wdt_device.bootstatus = s3c2410wdt_get_bootstatus(wdt); > wdt->wdt_device.parent = dev; > > + /* > + * If "tmr_atboot" param is non-zero, start the watchdog right now. Also > + * set WDOG_HW_RUNNING bit, so that watchdog core can kick the watchdog. > + * > + * If we're not enabling the watchdog, then ensure it is disabled if it > + * has been left running from the bootloader or other source. > + */ > + if (tmr_atboot && started == 0) { > + dev_info(dev, "starting watchdog timer\n"); > + s3c2410wdt_start(&wdt->wdt_device); > + set_bit(WDOG_HW_RUNNING, &wdt->wdt_device.status); > + } else if (!tmr_atboot) { > + s3c2410wdt_stop(&wdt->wdt_device); > + } > + > ret = watchdog_register_device(&wdt->wdt_device); > if (ret) > goto err_cpufreq; > @@ -740,17 +755,6 @@ static int s3c2410wdt_probe(struct platform_device *pdev) > if (ret < 0) > goto err_unregister; > > - if (tmr_atboot && started == 0) { > - dev_info(dev, "starting watchdog timer\n"); > - s3c2410wdt_start(&wdt->wdt_device); > - } else if (!tmr_atboot) { > - /* if we're not enabling the watchdog, then ensure it is > - * disabled if it has been left running from the bootloader > - * or other source */ > - > - s3c2410wdt_stop(&wdt->wdt_device); > - } > - > platform_set_drvdata(pdev, wdt); > > /* print out a statement of readiness */ > Best regards, Krzysztof
On Fri, 29 Oct 2021 at 03:30, Guenter Roeck <linux@roeck-us.net> wrote: > > On 10/28/21 11:35 AM, Sam Protsenko wrote: > > When "tmr_atboot" module param is set, the watchdog is started in > > driver's probe. In that case, also set WDOG_HW_RUNNING bit to let > > watchdog core driver know it's running. This way wathcdog core can kick > > the watchdog for us (if CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED option is > > enabled), until user space takes control. > > > > Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org> > > --- > > drivers/watchdog/s3c2410_wdt.c | 26 +++++++++++++++----------- > > 1 file changed, 15 insertions(+), 11 deletions(-) > > > > diff --git a/drivers/watchdog/s3c2410_wdt.c b/drivers/watchdog/s3c2410_wdt.c > > index ca082b1226e3..9af014ff1468 100644 > > --- a/drivers/watchdog/s3c2410_wdt.c > > +++ b/drivers/watchdog/s3c2410_wdt.c > > @@ -732,6 +732,21 @@ static int s3c2410wdt_probe(struct platform_device *pdev) > > wdt->wdt_device.bootstatus = s3c2410wdt_get_bootstatus(wdt); > > wdt->wdt_device.parent = dev; > > > > + /* > > + * If "tmr_atboot" param is non-zero, start the watchdog right now. Also > > + * set WDOG_HW_RUNNING bit, so that watchdog core can kick the watchdog. > > + * > > + * If we're not enabling the watchdog, then ensure it is disabled if it > > + * has been left running from the bootloader or other source. > > + */ > > + if (tmr_atboot && started == 0) { > > + dev_info(dev, "starting watchdog timer\n"); > > + s3c2410wdt_start(&wdt->wdt_device); > > + set_bit(WDOG_HW_RUNNING, &wdt->wdt_device.status); > > + } else if (!tmr_atboot) { > > + s3c2410wdt_stop(&wdt->wdt_device); > > + } > > + > > This doesn't cover the case where the watchdog is already enabled by the BIOS. > In that case, WDOG_HW_RUNNING won't be set, and the watchdog will time out > if the userspace handler is not loaded fast enough. The code should consistently > set WDOG_HW_RUNNING if the watchdog is running. > As I understand, in the case when bootloader started the watchdog, the driver just stops it. You can see it in the code you replied to. } else if (!tmr_atboot) { s3c2410wdt_stop(&wdt->wdt_device); In other words, having "tmr_atboot" module param makes it irrelevant whether bootloader enabled WDT or no. > Guenter > > > ret = watchdog_register_device(&wdt->wdt_device); > > if (ret) > > goto err_cpufreq; > > @@ -740,17 +755,6 @@ static int s3c2410wdt_probe(struct platform_device *pdev) > > if (ret < 0) > > goto err_unregister; > > > > - if (tmr_atboot && started == 0) { > > - dev_info(dev, "starting watchdog timer\n"); > > - s3c2410wdt_start(&wdt->wdt_device); > > - } else if (!tmr_atboot) { > > - /* if we're not enabling the watchdog, then ensure it is > > - * disabled if it has been left running from the bootloader > > - * or other source */ > > - > > - s3c2410wdt_stop(&wdt->wdt_device); > > - } > > - > > platform_set_drvdata(pdev, wdt); > > > > /* print out a statement of readiness */ > > >
On Fri, 29 Oct 2021 at 11:20, Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com> wrote: > > On 28/10/2021 20:35, Sam Protsenko wrote: > > When "tmr_atboot" module param is set, the watchdog is started in > > driver's probe. In that case, also set WDOG_HW_RUNNING bit to let > > watchdog core driver know it's running. This way wathcdog core can kick > > s/wathcdog/watchdog/ > > > the watchdog for us (if CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED option is > > enabled), until user space takes control. > > This does not explain why you move the code around. I guess you miss > here information that we should start the watchdog before registering > it? If so please explain why. > Will do in v2, thanks. > > > > Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org> > > --- > > drivers/watchdog/s3c2410_wdt.c | 26 +++++++++++++++----------- > > 1 file changed, 15 insertions(+), 11 deletions(-) > > > > diff --git a/drivers/watchdog/s3c2410_wdt.c b/drivers/watchdog/s3c2410_wdt.c > > index ca082b1226e3..9af014ff1468 100644 > > --- a/drivers/watchdog/s3c2410_wdt.c > > +++ b/drivers/watchdog/s3c2410_wdt.c > > @@ -732,6 +732,21 @@ static int s3c2410wdt_probe(struct platform_device *pdev) > > wdt->wdt_device.bootstatus = s3c2410wdt_get_bootstatus(wdt); > > wdt->wdt_device.parent = dev; > > > > + /* > > + * If "tmr_atboot" param is non-zero, start the watchdog right now. Also > > + * set WDOG_HW_RUNNING bit, so that watchdog core can kick the watchdog. > > + * > > + * If we're not enabling the watchdog, then ensure it is disabled if it > > + * has been left running from the bootloader or other source. > > + */ > > + if (tmr_atboot && started == 0) { > > + dev_info(dev, "starting watchdog timer\n"); > > + s3c2410wdt_start(&wdt->wdt_device); > > + set_bit(WDOG_HW_RUNNING, &wdt->wdt_device.status); > > + } else if (!tmr_atboot) { > > + s3c2410wdt_stop(&wdt->wdt_device); > > + } > > + > > ret = watchdog_register_device(&wdt->wdt_device); > > if (ret) > > goto err_cpufreq; > > @@ -740,17 +755,6 @@ static int s3c2410wdt_probe(struct platform_device *pdev) > > if (ret < 0) > > goto err_unregister; > > > > - if (tmr_atboot && started == 0) { > > - dev_info(dev, "starting watchdog timer\n"); > > - s3c2410wdt_start(&wdt->wdt_device); > > - } else if (!tmr_atboot) { > > - /* if we're not enabling the watchdog, then ensure it is > > - * disabled if it has been left running from the bootloader > > - * or other source */ > > - > > - s3c2410wdt_stop(&wdt->wdt_device); > > - } > > - > > platform_set_drvdata(pdev, wdt); > > > > /* print out a statement of readiness */ > > > > > Best regards, > Krzysztof
On 10/30/21 7:29 AM, Sam Protsenko wrote: > On Fri, 29 Oct 2021 at 03:30, Guenter Roeck <linux@roeck-us.net> wrote: >> >> On 10/28/21 11:35 AM, Sam Protsenko wrote: >>> When "tmr_atboot" module param is set, the watchdog is started in >>> driver's probe. In that case, also set WDOG_HW_RUNNING bit to let >>> watchdog core driver know it's running. This way wathcdog core can kick >>> the watchdog for us (if CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED option is >>> enabled), until user space takes control. >>> >>> Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org> >>> --- >>> drivers/watchdog/s3c2410_wdt.c | 26 +++++++++++++++----------- >>> 1 file changed, 15 insertions(+), 11 deletions(-) >>> >>> diff --git a/drivers/watchdog/s3c2410_wdt.c b/drivers/watchdog/s3c2410_wdt.c >>> index ca082b1226e3..9af014ff1468 100644 >>> --- a/drivers/watchdog/s3c2410_wdt.c >>> +++ b/drivers/watchdog/s3c2410_wdt.c >>> @@ -732,6 +732,21 @@ static int s3c2410wdt_probe(struct platform_device *pdev) >>> wdt->wdt_device.bootstatus = s3c2410wdt_get_bootstatus(wdt); >>> wdt->wdt_device.parent = dev; >>> >>> + /* >>> + * If "tmr_atboot" param is non-zero, start the watchdog right now. Also >>> + * set WDOG_HW_RUNNING bit, so that watchdog core can kick the watchdog. >>> + * >>> + * If we're not enabling the watchdog, then ensure it is disabled if it >>> + * has been left running from the bootloader or other source. >>> + */ >>> + if (tmr_atboot && started == 0) { >>> + dev_info(dev, "starting watchdog timer\n"); >>> + s3c2410wdt_start(&wdt->wdt_device); >>> + set_bit(WDOG_HW_RUNNING, &wdt->wdt_device.status); >>> + } else if (!tmr_atboot) { >>> + s3c2410wdt_stop(&wdt->wdt_device); >>> + } >>> + >> >> This doesn't cover the case where the watchdog is already enabled by the BIOS. >> In that case, WDOG_HW_RUNNING won't be set, and the watchdog will time out >> if the userspace handler is not loaded fast enough. The code should consistently >> set WDOG_HW_RUNNING if the watchdog is running. >> > > As I understand, in the case when bootloader started the watchdog, the > driver just stops it. You can see it in the code you replied to. > > } else if (!tmr_atboot) { > s3c2410wdt_stop(&wdt->wdt_device); > > In other words, having "tmr_atboot" module param makes it irrelevant > whether bootloader enabled WDT or no. > Sure, but I am concerned about "if (tmr_atboot && started)", which doesn't set WDOG_HW_RUNNING with your current code, and I was looking for something like if (tmr_atboot) { if (!started) { dev_info(dev, "starting watchdog timer\n"); s3c2410wdt_start(&wdt->wdt_device); } set_bit(WDOG_HW_RUNNING, &wdt->wdt_device.status); } else { s3c2410wdt_stop(&wdt->wdt_device); } Guenter
On Sat, 30 Oct 2021 at 18:14, Guenter Roeck <linux@roeck-us.net> wrote: > > On 10/30/21 7:29 AM, Sam Protsenko wrote: > > On Fri, 29 Oct 2021 at 03:30, Guenter Roeck <linux@roeck-us.net> wrote: > >> > >> On 10/28/21 11:35 AM, Sam Protsenko wrote: > >>> When "tmr_atboot" module param is set, the watchdog is started in > >>> driver's probe. In that case, also set WDOG_HW_RUNNING bit to let > >>> watchdog core driver know it's running. This way wathcdog core can kick > >>> the watchdog for us (if CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED option is > >>> enabled), until user space takes control. > >>> > >>> Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org> > >>> --- > >>> drivers/watchdog/s3c2410_wdt.c | 26 +++++++++++++++----------- > >>> 1 file changed, 15 insertions(+), 11 deletions(-) > >>> > >>> diff --git a/drivers/watchdog/s3c2410_wdt.c b/drivers/watchdog/s3c2410_wdt.c > >>> index ca082b1226e3..9af014ff1468 100644 > >>> --- a/drivers/watchdog/s3c2410_wdt.c > >>> +++ b/drivers/watchdog/s3c2410_wdt.c > >>> @@ -732,6 +732,21 @@ static int s3c2410wdt_probe(struct platform_device *pdev) > >>> wdt->wdt_device.bootstatus = s3c2410wdt_get_bootstatus(wdt); > >>> wdt->wdt_device.parent = dev; > >>> > >>> + /* > >>> + * If "tmr_atboot" param is non-zero, start the watchdog right now. Also > >>> + * set WDOG_HW_RUNNING bit, so that watchdog core can kick the watchdog. > >>> + * > >>> + * If we're not enabling the watchdog, then ensure it is disabled if it > >>> + * has been left running from the bootloader or other source. > >>> + */ > >>> + if (tmr_atboot && started == 0) { > >>> + dev_info(dev, "starting watchdog timer\n"); > >>> + s3c2410wdt_start(&wdt->wdt_device); > >>> + set_bit(WDOG_HW_RUNNING, &wdt->wdt_device.status); > >>> + } else if (!tmr_atboot) { > >>> + s3c2410wdt_stop(&wdt->wdt_device); > >>> + } > >>> + > >> > >> This doesn't cover the case where the watchdog is already enabled by the BIOS. > >> In that case, WDOG_HW_RUNNING won't be set, and the watchdog will time out > >> if the userspace handler is not loaded fast enough. The code should consistently > >> set WDOG_HW_RUNNING if the watchdog is running. > >> > > > > As I understand, in the case when bootloader started the watchdog, the > > driver just stops it. You can see it in the code you replied to. > > > > } else if (!tmr_atboot) { > > s3c2410wdt_stop(&wdt->wdt_device); > > > > In other words, having "tmr_atboot" module param makes it irrelevant > > whether bootloader enabled WDT or no. > > > > Sure, but I am concerned about "if (tmr_atboot && started)", which doesn't > set WDOG_HW_RUNNING with your current code, and I was looking for something > like > > if (tmr_atboot) { > if (!started) { > dev_info(dev, "starting watchdog timer\n"); > s3c2410wdt_start(&wdt->wdt_device); > } > set_bit(WDOG_HW_RUNNING, &wdt->wdt_device.status); > } else { > s3c2410wdt_stop(&wdt->wdt_device); > } > Wow, I really overlooked that case. Nice catch! Not having '} else {' section is vicious... Though if started != 0, it means s3c2410wdt_set_heartbeat() failed to set wdd->timeout, and without that the watchdog core won't be able to calculate correctly ping interval in watchdog_next_keepalive(), and WDOG_HW_RUNNING bit won't do much good, right? So I'll probably just call s3c2410wdt_stop() in that case, to be on the safe side. Also this 'started' variable name is misleading, I'll convert it to "bool timeout_ok" while at it. > Guenter
On 10/30/21 9:59 AM, Sam Protsenko wrote: > On Sat, 30 Oct 2021 at 18:14, Guenter Roeck <linux@roeck-us.net> wrote: >> >> On 10/30/21 7:29 AM, Sam Protsenko wrote: >>> On Fri, 29 Oct 2021 at 03:30, Guenter Roeck <linux@roeck-us.net> wrote: >>>> >>>> On 10/28/21 11:35 AM, Sam Protsenko wrote: >>>>> When "tmr_atboot" module param is set, the watchdog is started in >>>>> driver's probe. In that case, also set WDOG_HW_RUNNING bit to let >>>>> watchdog core driver know it's running. This way wathcdog core can kick >>>>> the watchdog for us (if CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED option is >>>>> enabled), until user space takes control. >>>>> >>>>> Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org> >>>>> --- >>>>> drivers/watchdog/s3c2410_wdt.c | 26 +++++++++++++++----------- >>>>> 1 file changed, 15 insertions(+), 11 deletions(-) >>>>> >>>>> diff --git a/drivers/watchdog/s3c2410_wdt.c b/drivers/watchdog/s3c2410_wdt.c >>>>> index ca082b1226e3..9af014ff1468 100644 >>>>> --- a/drivers/watchdog/s3c2410_wdt.c >>>>> +++ b/drivers/watchdog/s3c2410_wdt.c >>>>> @@ -732,6 +732,21 @@ static int s3c2410wdt_probe(struct platform_device *pdev) >>>>> wdt->wdt_device.bootstatus = s3c2410wdt_get_bootstatus(wdt); >>>>> wdt->wdt_device.parent = dev; >>>>> >>>>> + /* >>>>> + * If "tmr_atboot" param is non-zero, start the watchdog right now. Also >>>>> + * set WDOG_HW_RUNNING bit, so that watchdog core can kick the watchdog. >>>>> + * >>>>> + * If we're not enabling the watchdog, then ensure it is disabled if it >>>>> + * has been left running from the bootloader or other source. >>>>> + */ >>>>> + if (tmr_atboot && started == 0) { >>>>> + dev_info(dev, "starting watchdog timer\n"); >>>>> + s3c2410wdt_start(&wdt->wdt_device); >>>>> + set_bit(WDOG_HW_RUNNING, &wdt->wdt_device.status); >>>>> + } else if (!tmr_atboot) { >>>>> + s3c2410wdt_stop(&wdt->wdt_device); >>>>> + } >>>>> + >>>> >>>> This doesn't cover the case where the watchdog is already enabled by the BIOS. >>>> In that case, WDOG_HW_RUNNING won't be set, and the watchdog will time out >>>> if the userspace handler is not loaded fast enough. The code should consistently >>>> set WDOG_HW_RUNNING if the watchdog is running. >>>> >>> >>> As I understand, in the case when bootloader started the watchdog, the >>> driver just stops it. You can see it in the code you replied to. >>> >>> } else if (!tmr_atboot) { >>> s3c2410wdt_stop(&wdt->wdt_device); >>> >>> In other words, having "tmr_atboot" module param makes it irrelevant >>> whether bootloader enabled WDT or no. >>> >> >> Sure, but I am concerned about "if (tmr_atboot && started)", which doesn't >> set WDOG_HW_RUNNING with your current code, and I was looking for something >> like >> >> if (tmr_atboot) { >> if (!started) { >> dev_info(dev, "starting watchdog timer\n"); >> s3c2410wdt_start(&wdt->wdt_device); >> } >> set_bit(WDOG_HW_RUNNING, &wdt->wdt_device.status); >> } else { >> s3c2410wdt_stop(&wdt->wdt_device); >> } >> > > Wow, I really overlooked that case. Nice catch! Not having '} else {' > section is vicious... > > Though if started != 0, it means s3c2410wdt_set_heartbeat() failed to > set wdd->timeout, and without that the watchdog core won't be able to > calculate correctly ping interval in watchdog_next_keepalive(), and > WDOG_HW_RUNNING bit won't do much good, right? So I'll probably just > call s3c2410wdt_stop() in that case, to be on the safe side. > > Also this 'started' variable name is misleading, I'll convert it to > "bool timeout_ok" while at it. > This driver is a mess :-(. "started" true means that the driver doesn't work as currently written because there is no known valid timeout. In reality, s3c2410wdt_set_heartbeat() should in that case select a valid timeout and set it. On top of that, a timeout value out of range should never be passed to it in the first place. The check for "if (timeout < 1)" is, in that context, pointless. The range check should happen in s3c2410wdt_max_timeout(). If that range check is invalid, ie if s3c2410wdt_set_heartbeat() fails even though the timeout is in the range of 1 ..s3c2410wdt_max_timeout(), s3c2410wdt_max_timeout() is buggy. The simplest fix (kludge/hack) might be to fail driver installation if s3c2410wdt_set_heartbeat() fails. Guenter
On Sat, 30 Oct 2021 at 20:47, Guenter Roeck <linux@roeck-us.net> wrote: > > On 10/30/21 9:59 AM, Sam Protsenko wrote: > > On Sat, 30 Oct 2021 at 18:14, Guenter Roeck <linux@roeck-us.net> wrote: > >> > >> On 10/30/21 7:29 AM, Sam Protsenko wrote: > >>> On Fri, 29 Oct 2021 at 03:30, Guenter Roeck <linux@roeck-us.net> wrote: > >>>> > >>>> On 10/28/21 11:35 AM, Sam Protsenko wrote: > >>>>> When "tmr_atboot" module param is set, the watchdog is started in > >>>>> driver's probe. In that case, also set WDOG_HW_RUNNING bit to let > >>>>> watchdog core driver know it's running. This way wathcdog core can kick > >>>>> the watchdog for us (if CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED option is > >>>>> enabled), until user space takes control. > >>>>> > >>>>> Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org> > >>>>> --- > >>>>> drivers/watchdog/s3c2410_wdt.c | 26 +++++++++++++++----------- > >>>>> 1 file changed, 15 insertions(+), 11 deletions(-) > >>>>> > >>>>> diff --git a/drivers/watchdog/s3c2410_wdt.c b/drivers/watchdog/s3c2410_wdt.c > >>>>> index ca082b1226e3..9af014ff1468 100644 > >>>>> --- a/drivers/watchdog/s3c2410_wdt.c > >>>>> +++ b/drivers/watchdog/s3c2410_wdt.c > >>>>> @@ -732,6 +732,21 @@ static int s3c2410wdt_probe(struct platform_device *pdev) > >>>>> wdt->wdt_device.bootstatus = s3c2410wdt_get_bootstatus(wdt); > >>>>> wdt->wdt_device.parent = dev; > >>>>> > >>>>> + /* > >>>>> + * If "tmr_atboot" param is non-zero, start the watchdog right now. Also > >>>>> + * set WDOG_HW_RUNNING bit, so that watchdog core can kick the watchdog. > >>>>> + * > >>>>> + * If we're not enabling the watchdog, then ensure it is disabled if it > >>>>> + * has been left running from the bootloader or other source. > >>>>> + */ > >>>>> + if (tmr_atboot && started == 0) { > >>>>> + dev_info(dev, "starting watchdog timer\n"); > >>>>> + s3c2410wdt_start(&wdt->wdt_device); > >>>>> + set_bit(WDOG_HW_RUNNING, &wdt->wdt_device.status); > >>>>> + } else if (!tmr_atboot) { > >>>>> + s3c2410wdt_stop(&wdt->wdt_device); > >>>>> + } > >>>>> + > >>>> > >>>> This doesn't cover the case where the watchdog is already enabled by the BIOS. > >>>> In that case, WDOG_HW_RUNNING won't be set, and the watchdog will time out > >>>> if the userspace handler is not loaded fast enough. The code should consistently > >>>> set WDOG_HW_RUNNING if the watchdog is running. > >>>> > >>> > >>> As I understand, in the case when bootloader started the watchdog, the > >>> driver just stops it. You can see it in the code you replied to. > >>> > >>> } else if (!tmr_atboot) { > >>> s3c2410wdt_stop(&wdt->wdt_device); > >>> > >>> In other words, having "tmr_atboot" module param makes it irrelevant > >>> whether bootloader enabled WDT or no. > >>> > >> > >> Sure, but I am concerned about "if (tmr_atboot && started)", which doesn't > >> set WDOG_HW_RUNNING with your current code, and I was looking for something > >> like > >> > >> if (tmr_atboot) { > >> if (!started) { > >> dev_info(dev, "starting watchdog timer\n"); > >> s3c2410wdt_start(&wdt->wdt_device); > >> } > >> set_bit(WDOG_HW_RUNNING, &wdt->wdt_device.status); > >> } else { > >> s3c2410wdt_stop(&wdt->wdt_device); > >> } > >> > > > > Wow, I really overlooked that case. Nice catch! Not having '} else {' > > section is vicious... > > > > Though if started != 0, it means s3c2410wdt_set_heartbeat() failed to > > set wdd->timeout, and without that the watchdog core won't be able to > > calculate correctly ping interval in watchdog_next_keepalive(), and > > WDOG_HW_RUNNING bit won't do much good, right? So I'll probably just > > call s3c2410wdt_stop() in that case, to be on the safe side. > > > > Also this 'started' variable name is misleading, I'll convert it to > > "bool timeout_ok" while at it. > > > > This driver is a mess :-(. "started" true means that the driver doesn't > work as currently written because there is no known valid timeout. In > reality, s3c2410wdt_set_heartbeat() should in that case select a valid > timeout and set it. On top of that, a timeout value out of range should > never be passed to it in the first place. The check for "if (timeout < 1)" > is, in that context, pointless. The range check should happen in > s3c2410wdt_max_timeout(). If that range check is invalid, ie if > s3c2410wdt_set_heartbeat() fails even though the timeout is in the range > of 1 ..s3c2410wdt_max_timeout(), s3c2410wdt_max_timeout() is buggy. > > The simplest fix (kludge/hack) might be to fail driver installation if > s3c2410wdt_set_heartbeat() fails. > Thanks for suggesting that. I'll send that change along in v2. > Guenter
diff --git a/drivers/watchdog/s3c2410_wdt.c b/drivers/watchdog/s3c2410_wdt.c index ca082b1226e3..9af014ff1468 100644 --- a/drivers/watchdog/s3c2410_wdt.c +++ b/drivers/watchdog/s3c2410_wdt.c @@ -732,6 +732,21 @@ static int s3c2410wdt_probe(struct platform_device *pdev) wdt->wdt_device.bootstatus = s3c2410wdt_get_bootstatus(wdt); wdt->wdt_device.parent = dev; + /* + * If "tmr_atboot" param is non-zero, start the watchdog right now. Also + * set WDOG_HW_RUNNING bit, so that watchdog core can kick the watchdog. + * + * If we're not enabling the watchdog, then ensure it is disabled if it + * has been left running from the bootloader or other source. + */ + if (tmr_atboot && started == 0) { + dev_info(dev, "starting watchdog timer\n"); + s3c2410wdt_start(&wdt->wdt_device); + set_bit(WDOG_HW_RUNNING, &wdt->wdt_device.status); + } else if (!tmr_atboot) { + s3c2410wdt_stop(&wdt->wdt_device); + } + ret = watchdog_register_device(&wdt->wdt_device); if (ret) goto err_cpufreq; @@ -740,17 +755,6 @@ static int s3c2410wdt_probe(struct platform_device *pdev) if (ret < 0) goto err_unregister; - if (tmr_atboot && started == 0) { - dev_info(dev, "starting watchdog timer\n"); - s3c2410wdt_start(&wdt->wdt_device); - } else if (!tmr_atboot) { - /* if we're not enabling the watchdog, then ensure it is - * disabled if it has been left running from the bootloader - * or other source */ - - s3c2410wdt_stop(&wdt->wdt_device); - } - platform_set_drvdata(pdev, wdt); /* print out a statement of readiness */
When "tmr_atboot" module param is set, the watchdog is started in driver's probe. In that case, also set WDOG_HW_RUNNING bit to let watchdog core driver know it's running. This way wathcdog core can kick the watchdog for us (if CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED option is enabled), until user space takes control. Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org> --- drivers/watchdog/s3c2410_wdt.c | 26 +++++++++++++++----------- 1 file changed, 15 insertions(+), 11 deletions(-)