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    SubjectRe: [PATCH 3/4] iio: light: max44009: add missing OF device matching
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    On 11/03/2023 19:35, Jonathan Cameron wrote:
    > On Sat, 11 Mar 2023 13:28:17 +0100
    > Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> wrote:
    >
    >> On 11/03/2023 13:26, Jonathan Cameron wrote:
    >>> On Sat, 11 Mar 2023 12:14:56 +0100
    >>> Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> wrote:
    >>>
    >>>> The driver currently matches only via i2c_device_id, but also has
    >>>> of_device_id table:
    >>>>
    >>>> drivers/iio/light/max44009.c:545:34: error: ‘max44009_of_match’ defined but not used [-Werror=unused-const-variable=]
    >>>>
    >>>> Fixes: 6aef699a7d7e ("iio: light: add driver for MAX44009")
    >>>> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
    >>>
    >>> Don't use of_match_ptr() unless you are absolutely sure no other firmware
    >>> route will make use of the of_match_table.
    >>>
    >>> In this particular case ACPI using PRP0001 is broken by that macro.
    >>
    >> It's not broken because there was no matching via PRP0001 due to missing
    >> table.
    >>
    >>>
    >>> So good to set the of_match_table, but make sure to always set it
    >>> and hence you don't need the __maybe_unused.
    >>
    >> So you want to add PRP0001? We can, the fix is for different issue, though.
    >
    > There is nothing to add. You need to do less than you have done in this patch.
    > Drop the of_match_ptr() and the __maybe_unused and PRP0001 based matching will just
    > work. The PRP0001 path just uses the of_device_id table and needs no

    Sure, but that's *adding a feature*. You said that "ACPI using PRP0001
    is broken", but it was never here in the first place. PRP0001 *was*
    already broken here, not *is*. The patch does not decrease the
    functionality.

    > specific support in a driver - it doesn't need an ACPI id table or anything like
    > that.
    >
    > It's a long story, but hindsight says that of_match_ptr() should never have
    > existed as it only serves to stop things working that otherwise work for free.

    Sure, I can go with ID table always present.

    Best regards,
    Krzysztof

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