Re: [PATCH v2 2/2] media: imx335: Fix reset-gpio handling

[Krzysztof Kozlowski <krzk@kernel.org>]

On 30/07/2024 10:24, Sakari Ailus wrote:
> Hi Krzysztof,
> 
> On Mon, Jul 29, 2024 at 04:09:39PM +0200, Krzysztof Kozlowski wrote:
>> On 29/07/2024 13:04, Umang Jain wrote:
>>> Rectify the logical value of reset-gpio so that it is set to
>>> 0 (disabled) during power-on and to 1 (enabled) during power-off.
>>>
>>> Meanwhile at it, set the reset-gpio to GPIO_OUT_HIGH at initialization
>>> time to make sure it starts off in reset.
>>>
>>> Fixes: 45d19b5fb9ae ("media: i2c: Add imx335 camera sensor driver")
>>> Signed-off-by: Umang Jain <umang.jain@ideasonboard.com>
>>> ---
>>>  drivers/media/i2c/imx335.c | 8 ++++----
>>>  1 file changed, 4 insertions(+), 4 deletions(-)
>>>
>>
>> This will break all the users, so no. At least not without mentioning
>> ABI break and some sort of investigating how customers or users are
>> affected.
> 
> I know the original authors aren't using the driver anymore and it took
> quite a bit of time until others started to contribute to it so I suspect
> the driver hasn't been in use for that long. There are no instances of the
> device in the in-kernel DTS either.
> 
> Any DTS author should have also noticed the issue but of course there's a
> risk someone could have just changed the polarity and not bothered to chech
> what it was supposed to be.
> 
> I agree the commit message should be more vocal about the effects on
> existing DTS.

I can imagine that all users (out of tree, in this case) inverted
polarity in DTS based on what's implemented. You could go with some
trivial hack, like I did for one of codecs - see 738455858a2d ("ASoC:
codecs: wsa881x: Use proper shutdown GPIO polarity"), but I remember
Mark Brown rejected similar commit for newer drivers.

Best regards,
Krzysztof