Message ID | 20211203163539.91870-1-cniedermaier@dh-electronics.com (mailing list archive) |
---|---|
State | New, archived |
Headers | show |
Series | [RFC] watchdog: da9062: Correct the timeout values | expand |
On 12/3/21 8:35 AM, Christoph Niedermaier wrote: > I measured the timeout values of my DA9061 chip. According to the > information in the data sheet the formula should be: > > timeout = 2.048 * 2^(regval - 1) > > But my measured values differ from that. > Accoring to my measured values the formula must be: > > timeout = 3.2 * 2^(regval - 1) > > Is there something wrong with my chip, or has anyone else noticed this as well? The driver assumes a static and well defined clock rate. Maybe that rate is different in your system (if that is possible) ? Guenter > > Signed-off-by: Christoph Niedermaier <cniedermaier@dh-electronics.com> > Cc: Support Opensource <support.opensource@diasemi.com> > Cc: Adam Thomson <Adam.Thomson.Opensource@diasemi.com> > Cc: Wim Van Sebroeck <wim@linux-watchdog.org> > Cc: Guenter Roeck <linux@roeck-us.net> > Cc: Andrej Picej <andrej.picej@norik.com> > Cc: linux-watchdog@vger.kernel.org > Cc: linux-kernel@vger.kernel.org > To: linux-arm-kernel@lists.infradead.org > --- > drivers/watchdog/da9062_wdt.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/watchdog/da9062_wdt.c b/drivers/watchdog/da9062_wdt.c > index f02cbd530538..d2576aba9ca5 100644 > --- a/drivers/watchdog/da9062_wdt.c > +++ b/drivers/watchdog/da9062_wdt.c > @@ -20,7 +20,8 @@ > #include <linux/regmap.h> > #include <linux/of.h> > > -static const unsigned int wdt_timeout[] = { 0, 2, 4, 8, 16, 32, 65, 131 }; > +static const unsigned int wdt_timeout[] = { 0, 3, 6, 12, 25, 51, 102, 204 }; > + > #define DA9062_TWDSCALE_DISABLE 0 > #define DA9062_TWDSCALE_MIN 1 > #define DA9062_TWDSCALE_MAX (ARRAY_SIZE(wdt_timeout) - 1) >
From: Guenter Roeck Sent: Friday, December 3, 2021 5:52 PM > On 12/3/21 8:35 AM, Christoph Niedermaier wrote: >> I measured the timeout values of my DA9061 chip. According to the >> information in the data sheet the formula should be: >> >> timeout = 2.048 * 2^(regval - 1) >> >> But my measured values differ from that. >> Accoring to my measured values the formula must be: >> >> timeout = 3.2 * 2^(regval - 1) >> >> Is there something wrong with my chip, or has anyone else noticed this as well? > > The driver assumes a static and well defined clock rate. Maybe that rate > is different in your system (if that is possible) ? > > Guenter @Andrej Do the values in the driver match what your chip does? I have not changed anything. After power on, the chip behaves like this. So I guess it either come from an OTP value or the wiring outside the chip. Does anyone know what needs to be checked? Thanks and regards Christoph >> Signed-off-by: Christoph Niedermaier <cniedermaier@dh-electronics.com> >> Cc: Support Opensource <support.opensource@diasemi.com> >> Cc: Adam Thomson <Adam.Thomson.Opensource@diasemi.com> >> Cc: Wim Van Sebroeck <wim@linux-watchdog.org> >> Cc: Guenter Roeck <linux@roeck-us.net> >> Cc: Andrej Picej <andrej.picej@norik.com> >> Cc: linux-watchdog@vger.kernel.org >> Cc: linux-kernel@vger.kernel.org >> To: linux-arm-kernel@lists.infradead.org >> --- >> drivers/watchdog/da9062_wdt.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/watchdog/da9062_wdt.c b/drivers/watchdog/da9062_wdt.c >> index f02cbd530538..d2576aba9ca5 100644 >> --- a/drivers/watchdog/da9062_wdt.c >> +++ b/drivers/watchdog/da9062_wdt.c >> @@ -20,7 +20,8 @@ >> #include <linux/regmap.h> >> #include <linux/of.h> >> >> -static const unsigned int wdt_timeout[] = { 0, 2, 4, 8, 16, 32, 65, 131 }; >> +static const unsigned int wdt_timeout[] = { 0, 3, 6, 12, 25, 51, 102, 204 }; >> + >> #define DA9062_TWDSCALE_DISABLE 0 >> #define DA9062_TWDSCALE_MIN 1 >> #define DA9062_TWDSCALE_MAX (ARRAY_SIZE(wdt_timeout) - 1) >>
On 3. 12. 21 18:31, Christoph Niedermaier wrote: > From: Guenter Roeck > Sent: Friday, December 3, 2021 5:52 PM >> On 12/3/21 8:35 AM, Christoph Niedermaier wrote: >>> I measured the timeout values of my DA9061 chip. According to the >>> information in the data sheet the formula should be: >>> >>> timeout = 2.048 * 2^(regval - 1) >>> >>> But my measured values differ from that. >>> Accoring to my measured values the formula must be: >>> >>> timeout = 3.2 * 2^(regval - 1) >>> >>> Is there something wrong with my chip, or has anyone else noticed this as well? >> >> The driver assumes a static and well defined clock rate. Maybe that rate >> is different in your system (if that is possible) ? >> >> Guenter > > @Andrej > Do the values in the driver match what your chip does? > Just did a quick test. The values in the driver match what the chip does. I checked multiple timeouts 16, 32, 65 and 131 seconds. The timeout triggers quite accurately. > I have not changed anything. After power on, the chip behaves like this. > So I guess it either come from an OTP value or the wiring outside the chip. > Does anyone know what needs to be checked? Can't help you here, sorry. Best regards, Andrej
From: Andrej Picej Sent: Monday, December 6, 2021 8:29 AM >>>> I measured the timeout values of my DA9061 chip. According to the >>>> information in the data sheet the formula should be: >>>> >>>> timeout = 2.048 * 2^(regval - 1) >>>> >>>> But my measured values differ from that. >>>> Accoring to my measured values the formula must be: >>>> >>>> timeout = 3.2 * 2^(regval - 1) >>>> >>>> Is there something wrong with my chip, or has anyone else noticed this as well? >>> >>> The driver assumes a static and well defined clock rate. Maybe that rate >>> is different in your system (if that is possible) ? >>> >>> Guenter >> >> @Andrej >> Do the values in the driver match what your chip does? >> > > Just did a quick test. The values in the driver match what the chip > does. I checked multiple timeouts 16, 32, 65 and 131 seconds. The > timeout triggers quite accurately. > >> I have not changed anything. After power on, the chip behaves like this. >> So I guess it either come from an OTP value or the wiring outside the chip. >> Does anyone know what needs to be checked? > > Can't help you here, sorry. > Thanks anyway, so now I know it must be problem with my DA9061 chip. @Adam Where can it come from? Can you give we a hint what to check? Thanks and best regards Christoph
> Thanks anyway, so now I know it must be > problem with my DA9061 chip. > > @Adam > Where can it come from? > Can you give we a hint what to check? I've spoken internally and have been informed that this is down to the fact that DA9061 runs only from an internal oscillator which may be slower. The indication is that the values for TWDSCALE describe the window where if a kick/ping occurs within that period then the watchdog is guaranteed *not* to timeout. The actual timeout would be at some point after the selected timeout period, assuming no ping/kick occurred. Table 8 in the datasheet specifies a minimum watchdog timeout of 2.5s (tWDMAX) under specific operating conditions, so if the minimum 2s window was chosen (TWDSCALE = 1) then earliest the watchdog would actually timeout, following a ping, is 2.5s, assuming the conditions matched those described. If you have further questions it probably makes sense to contact Dialog/Renesas support as they will be able to provide more detailed info on this.
From: Adam Thomson Sent: Monday, December 6, 2021 5:38 PM >> Thanks anyway, so now I know it must be >> problem with my DA9061 chip. >> >> @Adam >> Where can it come from? >> Can you give we a hint what to check? > > I've spoken internally and have been informed that this is down to the fact that > DA9061 runs only from an internal oscillator which may be slower. The indication > is that the values for TWDSCALE describe the window where if a kick/ping occurs > within that period then the watchdog is guaranteed *not* to timeout. The actual > timeout would be at some point after the selected timeout period, assuming no > ping/kick occurred. > > Table 8 in the datasheet specifies a minimum watchdog timeout of 2.5s (tWDMAX) > under specific operating conditions, so if the minimum 2s window was chosen > (TWDSCALE = 1) then earliest the watchdog would actually timeout, following a > ping, is 2.5s, assuming the conditions matched those described. > > If you have further questions it probably makes sense to contact Dialog/Renesas > support as they will be able to provide more detailed info on this. So a DA9061 runs only from an internal oscillator, whereas a DA9062 can run on either an internal or an external oscillator. So this means that the DA9061 timeout values are differ from the DA9062 with an external oscillator not only on my device but on all DA9061 devices. This are the values (in seconds) in comparison: DA9062 (from driver): 0 2 4 8 16 32 65 131 DA9061 (measured): 0 3 6 12 25 51 102 204 ================================================= Difference: 0 +1 +2 +4 +9 +19 +37 +73 In my opinion, the differences in the higher values are very huge. If I expect that the watchdog triggers and I have to wait more than a minute for that to happen I ask myself is there something wrong. @Andrej I guess, you are using an external oscillator, aren't you? @Adam Is there a way to check in the driver which oscillator is in use? @Maintainers Is in the driver a need to distinguish between an external and an internal oscillator to get the timeout values more accurate? Best regards Christoph
diff --git a/drivers/watchdog/da9062_wdt.c b/drivers/watchdog/da9062_wdt.c index f02cbd530538..d2576aba9ca5 100644 --- a/drivers/watchdog/da9062_wdt.c +++ b/drivers/watchdog/da9062_wdt.c @@ -20,7 +20,8 @@ #include <linux/regmap.h> #include <linux/of.h> -static const unsigned int wdt_timeout[] = { 0, 2, 4, 8, 16, 32, 65, 131 }; +static const unsigned int wdt_timeout[] = { 0, 3, 6, 12, 25, 51, 102, 204 }; + #define DA9062_TWDSCALE_DISABLE 0 #define DA9062_TWDSCALE_MIN 1 #define DA9062_TWDSCALE_MAX (ARRAY_SIZE(wdt_timeout) - 1)
I measured the timeout values of my DA9061 chip. According to the information in the data sheet the formula should be: timeout = 2.048 * 2^(regval - 1) But my measured values differ from that. Accoring to my measured values the formula must be: timeout = 3.2 * 2^(regval - 1) Is there something wrong with my chip, or has anyone else noticed this as well? Signed-off-by: Christoph Niedermaier <cniedermaier@dh-electronics.com> Cc: Support Opensource <support.opensource@diasemi.com> Cc: Adam Thomson <Adam.Thomson.Opensource@diasemi.com> Cc: Wim Van Sebroeck <wim@linux-watchdog.org> Cc: Guenter Roeck <linux@roeck-us.net> Cc: Andrej Picej <andrej.picej@norik.com> Cc: linux-watchdog@vger.kernel.org Cc: linux-kernel@vger.kernel.org To: linux-arm-kernel@lists.infradead.org --- drivers/watchdog/da9062_wdt.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)