Am Donnerstag, 20. Oktober 2022, 14:36:10 CEST schrieb Andrej Picej: > On 20. 10. 22 14:18, Krzysztof Kozlowski wrote: > > On 20/10/2022 02:23, Andrej Picej wrote: > >> Hi Alexander and Krzysztof, > >> > >> hope I can reply to both questions here. > >> > >> On 19. 10. 22 17:51, Krzysztof Kozlowski wrote: > >>> On 19/10/2022 09:00, Alexander Stein wrote: > >>>> Hello Andrej, > >>> > >>>> Am Mittwoch, 19. Oktober 2022, 13:17:13 CEST schrieb Andrej Picej: > >>> Missing commit msg. > >>> > >>>>> Signed-off-by: Andrej Picej <andrej.picej@xxxxxxxxx> > >>>>> --- > >>>>> > >>>>> Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.yaml | 5 > >>>>> +++++ > >>>>> 1 file changed, 5 insertions(+) > >>>>> > >>>>> diff --git > >>>>> a/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.yaml > >>>>> b/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.yaml index > >>>>> fb7695515be1..01b3e04e7e65 100644 > >>>>> --- a/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.yaml > >>>>> +++ b/Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.yaml > >>>>> > >>>>> @@ -55,6 +55,11 @@ properties: > >>>>> If present, the watchdog device is configured to assert its > >>>>> external reset (WDOG_B) instead of issuing a software reset. > >>>>> > >>>>> + fsl,suspend-in-wait: > >>>>> + $ref: /schemas/types.yaml#/definitions/flag > >>>>> + description: | > >>>>> + If present, the watchdog device is suspended in WAIT mode. > >>>>> + > >>>>> > >>>>> required: > >>>>> - compatible > >>>>> - interrupts > >>>> > >>>> What is the condition the watchdog is suspended in WAIT mode? Is this > >>>> specific to SoC or platform or something else? > >> > >> Sorry, what exactly do you mean by condition? > > > > Ugh, I also cannot parse it now... Sorry, Krzysztof already asked the right question: When does one want to enable/disable this feature? > >> When the property > >> "fsl,suspend-in-wait" is set the watchdog is suspended in WAIT mode, so > >> this is defined by the user. Didn't want to apply it for all the > >> supported machines since there could be devices which depend on watchdog > >> triggering in WAIT mode. We stumbled on this problem on imx6 devices, > >> but the same bit (with the same description) is found on imx25, imx35, > >> imx50/51/53, imx7 and imx8. > > > > I meant, what is expected to happen if you do not enable this bit and > > watchdog triggers in WAIT mode? IOW, why someone might want to enable or > > disable this property? > > If this is not enabled and you put the device into the Suspend-to-idle > mode the device resets after 128 seconds. If not, the device can be left > in that state for infinite time. I'm guessing you want me to better > explain the property in device tree docs right? > I can do that in v2. > > >>> And what happens else? When it is not suspended in WAIT mode? > >> > >> When you put the device in "freeze"/"Suspend-To-Idle" low-power mode the > >> watchdog keeps running and triggers a reset after 128 seconds. So the > >> maximum length the device can stay in this mode is limited to 128 > >> seconds. > > > > And who wakes up the system before 128 seconds? IOW is there a use case > > of not enabling this property? > > Well I can think of one, system can be woken up by some other interrupt. > Like RTC which triggers interrupt (for example every 10s). So if this > property is left disabled the watchdog can handle errors where other > wakeup sources don't trigger interrupt or if the system is unable to > wake from low-power state. In that case the watchdog will do a hard > reset of the device. > > But I'm not really sure if anybody uses this, just wanted to make sure > that we keep the default behaviour as it is, since this driver is used > by many devices and for quite some time. This sounds more like (application) configuration. If so this should not be configured in device tree, IMHO. Best regards, Alexander
