linux-kernel - Re: [PATCH v1 2/2] dt-bindings: add bindings for QCOM flash LED

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Message-ID: <d6dc534f-2dc4-979c-ddad-c2122db7923a@linaro.org>
Date:   Thu, 29 Sep 2022 09:06:14 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Fenglin Wu <quic_fenglinw@...cinc.com>,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Pavel Machek <pavel@....cz>, Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        linux-leds@...r.kernel.org, devicetree@...r.kernel.org
Cc:     quic_collinsd@...cinc.com, quic_subbaram@...cinc.com
Subject: Re: [PATCH v1 2/2] dt-bindings: add bindings for QCOM flash LED

On 29/09/2022 04:20, Fenglin Wu wrote:
> 
> 
> On 2022/9/28 16:21, Krzysztof Kozlowski wrote:
>> On 28/09/2022 04:42, Fenglin Wu wrote:
>>> Add binding document for flash LED module inside Qualcomm Technologies,
>>> Inc. PMICs.
>>>
>>> Signed-off-by: Fenglin Wu <quic_fenglinw@...cinc.com>
>>
>> You did not Cc me on first patch, so difficult to say how much it
>> matches the driver... There is also no DTS.
> Thanks for reviewing the binding change, I sent the driver changes in 
> the same series and you can check it here:
> https://lore.kernel.org/linux-leds/6c0e5083-baae-3ed3-5eed-e08bbb9e7576@linaro.org/T/#m97f71ce3f291f62d65f8107352d8ab9507093ab2
> 
> I will add you in email to list when sending next patchset.

Don't add just mine. Use instead scripts/get_maintainers.pl. For small
patchsets recipients should get everything. For big patchsets it is
usually split, where everyone receive only cover letter. It's not the
case here...

>>
>>> ---
>>>   .../bindings/leds/leds-qcom-flash.yaml        | 108 ++++++++++++++++++
>>>   1 file changed, 108 insertions(+)
>>>   create mode 100644 Documentation/devicetree/bindings/leds/leds-qcom-flash.yaml
>>>
>>> diff --git a/Documentation/devicetree/bindings/leds/leds-qcom-flash.yaml b/Documentation/devicetree/bindings/leds/leds-qcom-flash.yaml
>>> new file mode 100644
>>> index 000000000000..52a99182961b
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/leds/leds-qcom-flash.yaml
>>
>>
>> Filename matching compatible if there is one fallback (e.g.
>> qcom,spmi-flash-led.yaml).
>>
> Sure, I will update the file name to match with the fallback compatible 
> string.
>>> @@ -0,0 +1,108 @@
>>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>>> +%YAML 1.2
>>> +---
>>> +$id: http://devicetree.org/schemas/leds/leds-qcom-flash.yaml#
>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>>> +
>>> +title: Flash LED device inside Qualcomm Technologies, Inc. PMICs
>>> +
>>> +maintainers:
>>> +  - Fenglin Wu <quic_fenglinw@...cinc.com>
>>> +
>>> +description: |
>>> +  Flash LED controller is present inside some Qualcomm Technologies, Inc. PMICs.
>>> +  The flash LED module can have different number of LED channels supported
>>> +  e.g. 3 or 4. There are some different registers between them but they can
>>> +  both support maximum current up to 1.5 A per channel and they can also support
>>> +  ganging 2 channels together to supply maximum current up to 2 A. The current
>>> +  will be split symmetrically on each channel and they will be enabled and
>>> +  disabled at the same time.
>>> +
>>> +properties:
>>> +  compatible:
>>> +    items:
>>> +      - enum:
>>> +          - qcom,spmi-flash-led
>>> +          - qcom,pm8150c-flash-led
>>> +          - qcom,pm8150l-flash-led
>>> +          - qcom,pm8350c-flash-led
>>
>> I doubt these are all different. You should use fallback, which also
>> will make use of the "items" you used...
> pm8150c and pm8150l are different PMIC variants which have same flash 
> LED module with 3 flash LED channels, while pm8350c has a different 
> flash LED module with 4 flash LED channels. They can all use 
> "qcom,spmi-flash-led" as the fallback because the driver has code logic 
> to detect HW sub-types. 

If driver binds to only one compatible, it is expected to be the
fallback for all others. There might be exception for this rule but it
does not look like here.

> But I was thinking to give out the PMIC names 
> here so anyone who is using the driver could easily identify if the 
> driver is suitable for the HW that he/she is using.

I did not say to remove other compatibles, but to use one fallback for
all of them.

Best regards,
Krzysztof