linux-kernel - Re: [PATCH] dt-bindings: mmc: fsl-imx-esdhc: allow more compatible combinations

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Date:   Sat, 7 Jan 2023 14:23:08 +0100
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Andreas Kemnade <andreas@...nade.info>
Cc:     ulf.hansson@...aro.org, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, shawnguo@...nel.org,
        s.hauer@...gutronix.de, kernel@...gutronix.de, festevam@...il.com,
        linux-imx@....com, linux-mmc@...r.kernel.org,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] dt-bindings: mmc: fsl-imx-esdhc: allow more compatible
 combinations

On 06/01/2023 20:33, Andreas Kemnade wrote:
> On Fri, 6 Jan 2023 09:41:01 +0100
> Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org> wrote:
> 
>> On 05/01/2023 22:38, Andreas Kemnade wrote:
>>> Currently make dtbs_check shows lots of errors because imx*.dtsi does
>>> not use single compatibles but combinations of them.
>>> Allow all the combinations used there.
>>>
>>> Patches fixing the dtsi files according to binding documentation were
>>> submitted multiple times and are commonly rejected, so relax the rules.
>>> Example:
>>> https://lore.kernel.org/linux-devicetree/72e1194e10ccb4f87aed96265114f0963e805092.camel@pengutronix.de/
>>>
>>> Reason: compatibility of new dtbs with old kernels or bootloaders.
>>>
>>> This will significantly reduce noise on make dtbs_check.
>>>
>>> Signed-off-by: Andreas Kemnade <andreas@...nade.info>
>>> ---
>>>  .../bindings/mmc/fsl-imx-esdhc.yaml           | 24 +++++++++++++++++++
>>>  1 file changed, 24 insertions(+)
>>>
>>> diff --git a/Documentation/devicetree/bindings/mmc/fsl-imx-esdhc.yaml b/Documentation/devicetree/bindings/mmc/fsl-imx-esdhc.yaml
>>> index dc6256f04b42..118ebb75f136 100644
>>> --- a/Documentation/devicetree/bindings/mmc/fsl-imx-esdhc.yaml
>>> +++ b/Documentation/devicetree/bindings/mmc/fsl-imx-esdhc.yaml
>>> @@ -37,6 +37,30 @@ properties:
>>>            - fsl,imx8mm-usdhc
>>>            - fsl,imxrt1050-usdhc
>>>            - nxp,s32g2-usdhc  
>>
>> You must drop the items from enum above. Binding saying:
>> compatible="A"
>> or:
>> compatible="A", "B"
>>
>> is not correct. Either A is or is not compatible with B.
>>
> hmm, here we have A = B + some additional features
> or
> A = B + some additional features and additional quirks required.

So why do you allow A alone?

> 
> For the latter we have e.g.
> A=
> static const struct esdhc_soc_data usdhc_imx6sx_data = {
>         .flags = ESDHC_FLAG_USDHC | ESDHC_FLAG_STD_TUNING
>                         | ESDHC_FLAG_HAVE_CAP1 | ESDHC_FLAG_HS200
>                         | ESDHC_FLAG_STATE_LOST_IN_LPMODE
>                         | ESDHC_FLAG_BROKEN_AUTO_CMD23,
> };
> B=
> static const struct esdhc_soc_data usdhc_imx6sl_data = {
>         .flags = ESDHC_FLAG_USDHC | ESDHC_FLAG_STD_TUNING
>                         | ESDHC_FLAG_HAVE_CAP1 | ESDHC_FLAG_ERR004536
>                         | ESDHC_FLAG_HS200
>                         | ESDHC_FLAG_BROKEN_AUTO_CMD23,
> };
> 
> so there is the difference in ESDHC_FLAG_STATE_LOST_IN_LPMODE.
> That might make no difference in some usage scenario (e.g. some bootloader
> not doing any LPMODE), but I wonder why
> we need to *enforce* specifying such half-compatible things.

I asked to remove half-compatible. Not to enforce.

Best regards,
Krzysztof