linux-kernel - Re: [PATCH 4/4] media: mt9m111: remove .s

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Date:   Thu, 18 Aug 2022 18:14:08 +0200
From:   Jacopo Mondi <jacopo@...ndi.org>
To:     Marco Felsch <m.felsch@...gutronix.de>
Cc:     mchehab@...nel.org, sakari.ailus@...ux.intel.com,
        laurent.pinchart+renesas@...asonboard.com,
        jacopo+renesas@...ndi.org, akinobu.mita@...il.com,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel@...gutronix.de
Subject: Re: [PATCH 4/4] media: mt9m111: remove .s_power callback

Hi Marco

On Thu, Aug 18, 2022 at 04:47:12PM +0200, Marco Felsch wrote:
> This is in preparation of switching to the generic dev PM mechanism.
> Since the .s_power callback will be removed in the near future move the
> powering into the .s_stream callback. So this driver no longer depends
> on the .s_power mechanism.
>
> Signed-off-by: Marco Felsch <m.felsch@...gutronix.de>

If you want to move to runtime_pm, I would implement it first and have
s_power call the _resume and _suspend routines, as some platform
drivers still use s_power() and some of them might depend on it.

It's a slippery slope.. I would love to get rid of s_power() but if
any platform uses it with this sensor, it would stop working after
this change.

> ---
>  drivers/media/i2c/mt9m111.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/media/i2c/mt9m111.c b/drivers/media/i2c/mt9m111.c
> index cd74c408e110..8e8ba5a8e6ea 100644
> --- a/drivers/media/i2c/mt9m111.c
> +++ b/drivers/media/i2c/mt9m111.c
> @@ -1065,7 +1065,6 @@ static const struct v4l2_ctrl_ops mt9m111_ctrl_ops = {
>  };
>
>  static const struct v4l2_subdev_core_ops mt9m111_subdev_core_ops = {
> -	.s_power	= mt9m111_s_power,
>  	.log_status = v4l2_ctrl_subdev_log_status,
>  	.subscribe_event = v4l2_ctrl_subdev_subscribe_event,
>  	.unsubscribe_event = v4l2_event_subdev_unsubscribe,
> @@ -1136,8 +1135,14 @@ static int mt9m111_enum_mbus_code(struct v4l2_subdev *sd,
>  static int mt9m111_s_stream(struct v4l2_subdev *sd, int enable)
>  {
>  	struct mt9m111 *mt9m111 = container_of(sd, struct mt9m111, subdev);
> +	int ret;
>
>  	mt9m111->is_streaming = !!enable;
> +
> +	ret = mt9m111_s_power(sd, enable);
> +	if (ret)
> +		return ret;
> +
>  	return 0;
>  }
>
> --
> 2.30.2
>