[PATCH v4] watchdog: stm32_iwdg: Add pretimeout support

[Marek Vasut]

On 12/11/24 10:02 AM, Clement LE GOFFIC wrote:
> On 4/15/24 15:48, Marek Vasut wrote:
>> The STM32MP15xx IWDG adds registers which permit this IP to generate
>> pretimeout interrupt. This interrupt can also be used to wake the CPU
>> from suspend. Implement support for generating this interrupt and let
>> userspace configure the pretimeout. In case the pretimeout is not
>> configured by user, set pretimeout to 3/4 of the WDT timeout cycle.
>>
>> Reviewed-by: Clément Le Goffic <clement.legoffic at foss.st.com>
>> Tested-by: Clément Le Goffic <clement.legoffic at foss.st.com>
>> Signed-off-by: Marek Vasut <marex at denx.de>
>> ---
>> Cc: Alexandre Torgue <alexandre.torgue at foss.st.com>
>> Cc: Guenter Roeck <linux at roeck-us.net>
>> Cc: Maxime Coquelin <mcoquelin.stm32 at gmail.com>
>> Cc: Wim Van Sebroeck <wim at linux-watchdog.org>
>> Cc: linux-arm-kernel at lists.infradead.org
>> Cc: linux-stm32 at st-md-mailman.stormreply.com
>> Cc: linux-watchdog at vger.kernel.org
>> ---
>> V2: - Subtract the pretimeout value from timeout value before writing it
>>        into the IWDG pretimeout register, because the watchdog counter
>>        register is counting down, and the pretimeout interrupt triggers
>>        when watchdog counter register matches the pretimeout register
>>        content.
>>      - Set default pretimeout to 3/4 of timeout .
>> V3: - Use dev instead of pdev->dev
>>      - Swap order of ret/return 0
>>      - Split this from the DT changes, which are orthogonal
>>      - Uh, this patch got stuck in upstreaming queue, sorry
>> V4: - Update commit message to match V2 default pretimeout to 3/4
>>      - Add RB/TB from Clément
>> ---
>>   drivers/watchdog/stm32_iwdg.c | 95 ++++++++++++++++++++++++++++++++++-
>>   1 file changed, 94 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/watchdog/stm32_iwdg.c b/drivers/watchdog/ 
>> stm32_iwdg.c
>> index 5404e03876202..d700e0d49bb95 100644
>> --- a/drivers/watchdog/stm32_iwdg.c
>> +++ b/drivers/watchdog/stm32_iwdg.c
>>
>>  [.....]
>>
>> +
>> +    irq = platform_get_irq(pdev, 0);
>> +    if (irq <= 0)
>> +        return 0;
> 
> Hi Marek,
> 
> After re-evaluating this patch, it seems it lacks of a dt-bindings 
> update that tackles the 'interrupts' property you are adding.
> 
> That said, the interrupt line should not be mandatory for the driver to 
> probe. For backward compatibility with existing DT, I recommend to use 
> the 'platform_get_irq_optional()' API to not fail during the probe of 
> the driver.
I saw the fix
[PATCH] watchdog: stm32_iwdg: fix DT backward compatibility
Thank you for that. I'll wait for V2 with updated commit message .

As far as I understood the problem, the goal is to remove error message 
printed by the platform_get_irq() in case the DT interrupt property is 
missing, but this is only an esthetic fix, not a functional one, because 
the driver probes even if the interrupts DT property is missing, it only 
prints the error message while at it, correct ?