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SubjectRe: [PATCH 1/7] Input: mtk-pmic-keys - check for NULL on of_match_device()
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Hi Dmitry,

Dmitry Torokhov <dmitry.torokhov@gmail.com> writes:

> Hi Mattijs,
>
> On Wed, Apr 28, 2021 at 06:42:13PM +0200, Mattijs Korpershoek wrote:
>> mtk-pmic-keys being a child device of mt6397, it will always get probed
>> when mt6397_probe() is called.
>>
>> This also happens when we have no device tree node matching
>> mediatek,mt6397-keys.
>
> It sounds for me that creating a platform device instance in case where
> we know need OF node, but do not have one, is wasteful. Can
> mt6397-core.c and/or MFD core be adjusted to not do that.

You are right. Maybe I can fix MFD core instead. I will look into it.

Thanks for your review.
>
>>
>> In that case, the mfd core warns us:
>>
>> [ 0.352175] mtk-pmic-keys: Failed to locate of_node [id: -1]
>>
>> Check return value from call to of_match_device()
>> in order to prevent a NULL pointer dereference.
>>
>> In case of NULL print error message and return -ENODEV
>>
>> Signed-off-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
>> ---
>> drivers/input/keyboard/mtk-pmic-keys.c | 3 +++
>> 1 file changed, 3 insertions(+)
>>
>> diff --git a/drivers/input/keyboard/mtk-pmic-keys.c b/drivers/input/keyboard/mtk-pmic-keys.c
>> index 62391d6c7da6..12c449eed026 100644
>> --- a/drivers/input/keyboard/mtk-pmic-keys.c
>> +++ b/drivers/input/keyboard/mtk-pmic-keys.c
>> @@ -247,6 +247,9 @@ static int mtk_pmic_keys_probe(struct platform_device *pdev)
>> const struct of_device_id *of_id =
>> of_match_device(of_mtk_pmic_keys_match_tbl, &pdev->dev);
>>
>> + if (!of_id)
>> + return -ENODEV;
>> +
>
> So if we make MFD/6396 core smarter we would not be needing this. I
> guess there is still a possibility of someone stuffing "mtk-pmic-keys"
> into "driver_override" attribute of a random platform device but I
> wonder if we really need to take care of such scenarios...
>
>> keys = devm_kzalloc(&pdev->dev, sizeof(*keys), GFP_KERNEL);
>> if (!keys)
>> return -ENOMEM;
>> --
>> 2.27.0
>>
>
> Thanks.
>
> --
> Dmitry

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