Re: [PATCH v2 00/11] media: adv7180: Improve the control over decoder power

[Hans Verkuil <hverkuil+cisco@kernel.org>]

On 28/08/2025 18:06, Niklas Söderlund wrote:
> Hello,
> 
> This series started as an effort to fix issues with querystd. To do that
> it turned out the whole drivers design around how it controls the power
> to the video decoder block inside the chip had to be reworked. As a
> bonus this works removes the now deprecated .s_power callback from
> adv7180.
> 
> The adv7180 drivers comes from a time before media controller and all
> operation callbacks are, more or less, designed around the concept that
> a video device is the only user-space facing API. In that world a vdev
> would attached the subdevice, call .s_power and then perform format
> configuration using the other operation callbacks and then start
> streaming with .s_stream. Needles to say this mode of operation don't
> work well with media controller where the subdevices itself have a
> user-space API exposed thru a subdev device.
> 
> The initial problem I tried to solve (querystd) was that it stopped
> functioning as expected after the subdev had been used to stream once
> (.s_power(1), .s_power(0)). As it turns out different variants of the
> adv7180 device have different reset beaver for if its video decoder
> block is left running or powered off. On my device it was left running
> so querystd functioned the first time, but not after the video decoder
> had been switched off once by .s_power(0).
> 
> I first tried to fix this by introducing proper PM handling in the
> driver to be able to remove the .s_power callback. I quickly learnt the
> power on/off logic happening in the driver had noting to do with
> controlling power to the chip itself, but to control if the chips video
> decoder block was turned off.
> 
> When this block is powered on the device process video data, if there is
> a video source else it free runs. However when the block is turned off
> the device can still be configured, in fact some configuration requires
> it to be off.
> 
> For this reason I dropped the effort to add proper PM handling and
> treated the decoder power as a stream on/off switch. I still think
> proper PM handling would be beneficial for this driver but to not
> explode this already large series I left that for another time. Solving
> the issue around .s_power will make that work easier as well as other
> task such as converting to the v4l2_subdev active state API.
> 
> Patch 1/11 just moves code around to make the consecutive changes easier
> to read. Patch 2/11 fix a locking issues when suspending the device.
> Patch 3/11 and 4/11 improves the locking design to prepare to improve
> the driver.
> 
> Patch 5/11 make sure the device controls are always programmed after the
> device have been reset, fixing a possible issue when the device where
> resumed from system sleep.
> 
> Patches 6/11, 7/11 and 8/11 is the real change where the .s_power
> callback is reworked to fit the design of .s_stream instead.
> 
> And finally patch 9/11, 10/11 and 11/11 removes programming of the
> device from operation callbacks and solves the issue with querystd.
> 
> The work is tested on R-Car M2 together with a ADV7180 device.
> 
> See individual patches for changelog.

This series looks good to me, other than the one typo and the
control handler kAPI issue, but that can be done in a follow-up
series.

If you want I can take this series, let me know.

Regards,

	Hans

> 
> Niklas Söderlund (11):
>   media: adv7180: Move adv7180_set_power() and init_device()
>   media: adv7180: Add missing lock in suspend callback
>   media: adv7180: Move state mutex handling outside init_device()
>   media: adv7180: Use v4l2-ctrls core to handle s_ctrl locking
>   media: adv7180: Setup controls every time the device is reset
>   media: adv7180: Power down decoder when configuring the device
>   media: adv7180: Split device initialization and reset
>   media: adv7180: Remove the s_power callback
>   media: adv7180: Do not write format to device in set_fmt
>   media: adv7180: Only validate format in s_std
>   media: adv7180: Only validate format in querystd
> 
>  drivers/media/i2c/adv7180.c | 338 +++++++++++++++++++-----------------
>  1 file changed, 174 insertions(+), 164 deletions(-)
>