Re: [RFC 18/18] power: supply: max17040: Do not enforce (incorrect) interrupt trigger type

[Iskren Chernev]

On 12/11/20 9:47 AM, Krzysztof Kozlowski wrote:
> On Thu, Dec 10, 2020 at 10:25:34PM +0100, Krzysztof Kozlowski wrote:
>> Interrupt line can be configured on different hardware in different way,
>> even inverted.  Therefore driver should not enforce specific trigger
>> type - edge falling - but instead rely on Devicetree to configure it.
>>
>> The Maxim 14577/77836 datasheets describe the interrupt line as active
>> low with a requirement of acknowledge from the CPU therefore the edge
>> falling is not correct.
>>
>> Signed-off-by: Krzysztof Kozlowski <krzk@xxxxxxxxxx>
>>
>> ---
>>
>> This patch should wait till DTS changes are merged, as it relies on
>> proper Devicetree.
>> ---
>> .../devicetree/bindings/power/supply/max17040_battery.txt       | 2 +-
>> drivers/power/supply/max17040_battery.c                         | 2 +-
>>  2 files changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git 
a/Documentation/devicetree/bindings/power/supply/max17040_battery.txt 
b/Documentation/devicetree/bindings/power/supply/max17040_battery.txt
>> index c802f664b508..194eb9fe574d 100644
>> --- 
a/Documentation/devicetree/bindings/power/supply/max17040_battery.txt
>> +++ 
b/Documentation/devicetree/bindings/power/supply/max17040_battery.txt
>> @@ -39,7 +39,7 @@ Example:
>>          reg = <0x36>;
>>          maxim,alert-low-soc-level = <10>;
>>          interrupt-parent = <&gpio7>;
>> -        interrupts = <2 IRQ_TYPE_EDGE_FALLING>;
>> +        interrupts = <2 IRQ_TYPE_LEVEL_LOW>;
>>          wakeup-source;
>>      };
>>
>> diff --git a/drivers/power/supply/max17040_battery.c 
b/drivers/power/supply/max17040_battery.c
>> index d956c67d5155..f737de0470de 100644
>> --- a/drivers/power/supply/max17040_battery.c
>> +++ b/drivers/power/supply/max17040_battery.c
>> @@ -367,7 +367,7 @@ static int max17040_enable_alert_irq(struct 
max17040_chip *chip)
>>
>>      flags = IRQF_TRIGGER_FALLING | IRQF_ONESHOT;
>
> This has to be removed. I will fix it in v2.
>
> Best regards,
> Krzysztof

I removed the IRQF_TRIGGER_FALLING, tweaked the DT as per the DT patch, and
it worked on the samsung klte.

I don't understand how the DT irq flag ends up being used by the kernel. It
is never explicitly read from DT or passed to interrupt API, only i2c->irq,
which is a pure int.

Fixing the DT and the drivers will hopefully set a precedent, so future
drivers (when copied/tweaked from existing drivers) will do it right.

Acked-by: Iskren Chernev <iskren.chernev@xxxxxxxxx>

>>      ret = devm_request_threaded_irq(&client->dev, client->irq, NULL,
>> -                    max17040_thread_handler, flags,
>> +                    max17040_thread_handler, IRQF_ONESHOT,
>>                      chip->battery->desc->name, chip);
>>
>>      return ret;
>> --
>> 2.25.1
>>