linux-kernel - Re: [PATCH v4 1/3] dt-bindings: vendor-prefixes: Add 'ltr' as deprecated vendor prefix

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Date:   Thu, 26 May 2022 13:03:04 +0530
From:   Shreeya Patel <shreeya.patel@...labora.com>
To:     Rob Herring <robh@...nel.org>
Cc:     jic23@...nel.org, lars@...afoo.de, Zhigang.Shi@...eon.com,
        krisman@...labora.com, linux-iio@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel@...labora.com, alvaro.soliverez@...labora.com,
        Krzysztof Kozlowski <krzk@...nel.org>
Subject: Re: [PATCH v4 1/3] dt-bindings: vendor-prefixes: Add 'ltr' as
 deprecated vendor prefix


On 24/05/22 21:17, Rob Herring wrote:
> On Mon, May 23, 2022 at 08:27:56PM +0530, Shreeya Patel wrote:
>> On 18/05/22 22:02, Rob Herring wrote:
>>> On Tue, May 17, 2022 at 04:07:33PM +0530, Shreeya Patel wrote:
>>>> On 16/05/22 22:30, Rob Herring wrote:
>>>>> On Wed, May 11, 2022 at 03:10:22PM +0530, Shreeya Patel wrote:
>>>>>> 'liteon' is the correct vendor prefix for devices released by
>>>>>> LITE-ON Technology Corp. But one of the released device which uses
>>>>>> ltr216a light sensor exposes the vendor prefix name as 'ltr' through
>>>>>> ACPI.
>>>>> ACPI? NAK.
>>>>>
>>>>> There are no cases of 'ltr' for DT, so fix ACPI.
>>>> Hi Rob,
>>>>
>>>> Yes, we understand there are no cases of 'ltr', but we have released devices
>>>> which uses this string for probing the ltrf216a light sensor driver ( x86
>>>> with DT )
>>> That's not what your commit message says.
>>>
>>> Even if this is DT based, given an undocumented vendor string is used,
>>> it seems doubtful the rest of the binding would match upstream. What
>>> about the rest of the DTB? Got a pointer to it or want to publish it?
>>>
>>>> If we don't document this in vendor-prefixes.yaml, then the following
>>>> warning
>>>> is generated.
>>>>
>>>> WARNING: DT compatible string vendor "ltr" appears un-documented -- check
>>>> ./Documentation/devicetree/bindings/vendor-prefixes.yaml 364: FILE:
>>>> drivers/iio/light/ltrf216a.c:313: + { .compatible = "ltr,ltrf216a" },
>>>>
>>>>
>>>> Can you suggest us what would be the right way to fix this warning if not
>>>> documenting
>>>> in vendor-prefixes.yaml?
>>> Fix the DT. We don't accept bindings simply because they are already
>>> used in the field. If this was the only issue, it would be fine, but I
>>> suspect it's the tip of the iceberg.
>>
>> Hi Rob,
>>
>> To make things more clear, following is the modalias info of the device.
>>
>> (B+)(root@...ux iio:device0)# cat
>> /sys/bus/i2c/devices/i2c-PRP0001\:01/modalias
>> of:NltrfTCltr,ltrf216a
>>
>> It's a dt namespace on an ACPI based device. We used an of_device_id table
>> to be able to probe the driver
>> using the vendor prefix and compatible string.
> Again, it's ACPI so I don't care. If someone cares about using DT
> bindings in ACPI they can step up and help maintain them. It's not a DT
> vs. ACPI thing, but just that I can only maintain so much and have to
> draw the line somewhere.
>
>> But when we compile the driver, we get the following warning and hence we
>> documented it in vendor-prefixes.yaml
>> and also added a complete device tree file [Patch 3/3] just to get rid of
>> the warning. In real life we are not using
>> the device tree file at all.
>>
>> WARNING: DT compatible string vendor "ltr" appears un-documented -- check
>> ./Documentation/devicetree/bindings/vendor-prefixes.yaml 364: FILE:
>> drivers/iio/light/ltrf216a.c:313: + { .compatible = "ltr,ltrf216a" },
> So, is someone telling you to fix this?


So will it be right to just keep the warning and remove this patch?
Is there a way you know to silent this warning?


Thanks,
Shreeya Patel

>
>
>> There are many existing devices used by people which has the vendor prefix
>> name as 'ltr'
>> and it won't be possible to change that hence we are trying to upstream it.
> There are millions if not billions of DT based devices using
> undocumented bindings. If those used "ltr,ltrf216a", I wouldn't accept
> it either.
>
> Rob
>