[PATCH v2 17/18] dt-bindings: pci: rockchip,rk3399-pcie-ep: Add ep-gpios property

[Damien Le Moal]

On 4/2/24 16:33, Krzysztof Kozlowski wrote:
> On 02/04/2024 01:36, Damien Le Moal wrote:
>> On 4/1/24 18:57, Krzysztof Kozlowski wrote:
>>> On 01/04/2024 01:06, Damien Le Moal wrote:
>>>> On 3/30/24 18:16, Krzysztof Kozlowski wrote:
>>>>> On 30/03/2024 05:19, Damien Le Moal wrote:
>>>>>> From: Wilfred Mallawa <wilfred.mallawa at wdc.com>
>>>>>>
>>>>>> Describe the `ep-gpios` property which is used to map the PERST# input
>>>>>> signal for endpoint mode.
>>>>>>
>>>>>> Signed-off-by: Wilfred Mallawa <wilfred.mallawa at wdc.com>
>>>>>> Signed-off-by: Damien Le Moal <dlemoal at kernel.org>
>>>>>> ---
>>>>>>  .../devicetree/bindings/pci/rockchip,rk3399-pcie-ep.yaml       | 3 +++
>>>>>>  1 file changed, 3 insertions(+)
>>>>>>
>>>>>> diff --git a/Documentation/devicetree/bindings/pci/rockchip,rk3399-pcie-ep.yaml b/Documentation/devicetree/bindings/pci/rockchip,rk3399-pcie-ep.yaml
>>>>>> index 6b62f6f58efe..9331d44d6963 100644
>>>>>> --- a/Documentation/devicetree/bindings/pci/rockchip,rk3399-pcie-ep.yaml
>>>>>> +++ b/Documentation/devicetree/bindings/pci/rockchip,rk3399-pcie-ep.yaml
>>>>>> @@ -30,6 +30,9 @@ properties:
>>>>>>      maximum: 32
>>>>>>      default: 32
>>>>>>  
>>>>>> +  ep-gpios:
>>>>>> +    description: Input GPIO configured for the PERST# signal.
>>>>>
>>>>> Missing maxItems. But more important: why existing property perst-gpios,
>>>>> which you already have there in common schema, is not correct for this case?
>>>>
>>>> I am confused... Where do you find perst-gpios defined for the rk3399 ?
>>>> Under Documentation/devicetree/bindings/pci/, the only schema I see using
>>>> perst-gpios property are for the qcom (Qualcomm) controllers.
>>>
>>> You are right, it's so far only in Qualcomm.
>>>
>>>> The RC bindings for the rockchip rk3399 PCIe controller
>>>> (pci/rockchip,rk3399-pcie.yaml) already define the ep-gpios property. So if
>>>
>>> Any reason why this cannot be named like GPIO? Is there already a user
>>> of this in Linux kernel? Commit msg says nothing about this, so that's
>>> why I would expect name matching the signal.
>>
>> The RC-mode PCIe controller node of the rk3399 DTS already defines the ep-gpios
>> property for RC side PERST# signal handling. So we simply reused the exact same
>> name to be consistent between RC and EP. I personnally have no preferences. If
>> there is an effort to rename such signal with some preferred pattern, I will
>> follow. For the EP node, there was no PERST signal handling in the driver and
>> no property defined for it, so any name is fine. "perst-gpios" would indeed be
>> a better name, but again, given that the RC controller node has ep-gpios, we
>> reused that. What is your recommendation here ?
> 
> Actually I don't know, perst and ep would work for me. If you do not
> have code for this in the driver yet (nothing is shared between ep and
> host), then maybe let's go with perst to match the actual name.

Forgot to add: the driver code for the EP PERST gpio handling is added in patch
18 of the series, after this one.

> 
> Anyway, you need maxItems. I sent a patch for the other binding:
> https://lore.kernel.org/all/20240401100058.15749-1-krzysztof.kozlowski@linaro.org/
> 
> Best regards,
> Krzysztof
> 

-- 
Damien Le Moal
Western Digital Research