Re: [PATCH v2 1/2] dt-bindings: gpio: Add gpio-line-names to STMPE GPIO

[Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>]

On 24/07/2023 13:44, Alexander Stein wrote:

>>>>>  Documentation/devicetree/bindings/gpio/st,stmpe-gpio.yaml | 4 ++++
>>>>>  1 file changed, 4 insertions(+)
>>>>>
>>>>> diff --git a/Documentation/devicetree/bindings/gpio/st,stmpe-gpio.yaml
>>>>> b/Documentation/devicetree/bindings/gpio/st,stmpe-gpio.yaml index
>>>>> 22c0cae73425..4555f1644a4d 100644
>>>>> --- a/Documentation/devicetree/bindings/gpio/st,stmpe-gpio.yaml
>>>>> +++ b/Documentation/devicetree/bindings/gpio/st,stmpe-gpio.yaml
>>>>>
>>>>> @@ -28,6 +28,10 @@ properties:
>>>>>    gpio-controller: true
>>>>>
>>>>> +  gpio-line-names:
>>>>> +    minItems: 1
>>>>> +    maxItems: 24
>>>>> +
>>>>
>>>> I am sure there is no variant with one GPIO.
>>>
>>> That's true. But if only one GPIO is actually connected there is no use
>>> enforcing to add empty entries.
>>> AFAIK it is also allowed to provide an incomplete array.
>>
>> Did you test it? Linux prints warning. Warning means "not allowed".
> 
> I did and I don't see any warnings.
> I using the following (modified) GPIO subnode on an stmpe811 chip:
> gpio {
> 	compatible = "st,stmpe-gpio";
> 	gpio-controller;
> 	#gpio-cells = <2>;
> 	interrupt-controller;
> 	#interrupt-cells = <2>;
> 	/* GPIO 5-7 used for touch */
> 	st,norequest-mask = <0xf0>;
> 	gpio-line-names = "GPIO_ADC_I2C1_1";
> };
> 
> I only see the warning "stmpe-gpio stmpe-gpio: DMA mask not set", but that's a 
> different matter.
> Only GPIO 0-3 are connected. Original property is
> gpio-line-names = "GPIO_ADC_I2C1_1",
> 	        "GPIO_ADC_I2C1_2",
> 	        "GPIO_ADC_I2C1_3",
> 	        "GPIO_ADC_I2C1_4";
> 
> Also gpioinfo shows that the gpiochip has 8 pins while only the first one is 
> named.
> 
> gpiochip7 - 8 lines:
>         line   0: "GPIO_ADC_I2C1_1" unused input active-high 
>         line   1:      unnamed       unused   input  active-high 
>         line   2:      unnamed       unused   input  active-high 
>         line   3:      unnamed       unused   input  active-high 
>         line   4:      unnamed       unused   input  active-high 
>         line   5:      unnamed       unused   input  active-high 
>         line   6:      unnamed       unused   input  active-high 
>         line   7:      unnamed       unused   input  active-high
> 
> 
> If 4 GPIOs are named the output shows names for lines 1-3 accordingly, but no 
> errors/warnings as well.
> 
>> The expectation is that the rest are named "NC".
> 
> Where does this expectation come from? Is there any pending change I am not 
> aware of?
> 

Hm, indeed, I mistaken the case for multiple gpio chips in one device
(so having an offset). Bindings are actually explicitly allowing array
for only some GPIOs.

Best regards,
Krzysztof