linux-kernel - Re: [PATCH 3/4] media: mt9m111: fix device power usage

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Date:   Fri, 19 Aug 2022 09:26:05 +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 3/4] media: mt9m111: fix device power usage

Hi Marco

On Thu, Aug 18, 2022 at 04:47:11PM +0200, Marco Felsch wrote:
> Currently the driver turn off the power after probe and toggle it during
> .stream by using the .s_power callback. This is problematic since other
> callbacks like .set_fmt accessing the hardware as well which will fail.

Ouch!

> So in the end the default format is the only supported format.
>
> Remove the hardware register access from the callbacks and instead sync
> the state once right before the stream gets enabled to fix this.

Where does it happen in this patch ?

>
> Signed-off-by: Marco Felsch <m.felsch@...gutronix.de>
> ---
>  drivers/media/i2c/mt9m111.c | 20 +++++++++++++-------
>  1 file changed, 13 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/media/i2c/mt9m111.c b/drivers/media/i2c/mt9m111.c
> index 53c4dac4e4bd..cd74c408e110 100644
> --- a/drivers/media/i2c/mt9m111.c
> +++ b/drivers/media/i2c/mt9m111.c
> @@ -481,8 +481,6 @@ static int mt9m111_set_selection(struct v4l2_subdev *sd,
>  	width = min(mt9m111->width, rect.width);
>  	height = min(mt9m111->height, rect.height);
>
> -

Why in mainline I don't see these empty lines ?

> -	mt9m111_setup_geometry(mt9m111, &rect, width, height, mt9m111->fmt->code);
>  	mt9m111->rect = rect;
>  	mt9m111->width = width;
>  	mt9m111->height = height;
> @@ -611,7 +609,6 @@ static int mt9m111_set_pixfmt(struct mt9m111 *mt9m111,
>  	if (mt9m111->pclk_sample == 0)
>  		mask_outfmt2 |= MT9M111_OUTFMT_INV_PIX_CLOCK;
>
> -
>  	mt9m111_reg_mask(client, context_a.output_fmt_ctrl2,
>  			 data_outfmt2, mask_outfmt2);
>  	mt9m111_reg_mask(client, context_b.output_fmt_ctrl2,
> @@ -678,9 +675,6 @@ static int mt9m111_set_fmt(struct v4l2_subdev *sd,
>  		return 0;
>  	}
>
> -
> -	mt9m111_setup_geometry(mt9m111, rect, mf->width, mf->height, mf->code);
> -	mt9m111_set_pixfmt(mt9m111, mf->code);

Are we looking at two different versions of the driver ??
https://elixir.bootlin.com/linux/latest/source/drivers/media/i2c/mt9m111.c#L684

>  	mt9m111->width	= mf->width;
>  	mt9m111->height	= mf->height;
>  	mt9m111->fmt	= fmt;
> @@ -743,6 +737,8 @@ mt9m111_find_mode(struct mt9m111 *mt9m111, unsigned int req_fps,
>  	return mode;
>  }
>
> +static int mt9m111_s_power(struct v4l2_subdev *sd, int on);
> +
>  #ifdef CONFIG_VIDEO_ADV_DEBUG
>  static int mt9m111_g_register(struct v4l2_subdev *sd,
>  			      struct v4l2_dbg_register *reg)
> @@ -753,10 +749,14 @@ static int mt9m111_g_register(struct v4l2_subdev *sd,
>  	if (reg->reg > 0x2ff)
>  		return -EINVAL;
>
> +	mt9m111_s_power(sd, 1);
> +
>  	val = mt9m111_reg_read(client, reg->reg);
>  	reg->size = 2;
>  	reg->val = (u64)val;
>
> +	mt9m111_s_power(sd, 0);
> +
>  	if (reg->val > 0xffff)
>  		return -EIO;
>
> @@ -771,9 +771,13 @@ static int mt9m111_s_register(struct v4l2_subdev *sd,
>  	if (reg->reg > 0x2ff)
>  		return -EINVAL;
>
> +	mt9m111_s_power(sd, 1);
> +
>  	if (mt9m111_reg_write(client, reg->reg, reg->val) < 0)
>  		return -EIO;
>
> +	mt9m111_s_power(sd, 0);
> +
>  	return 0;
>  }
>  #endif
> @@ -896,6 +900,9 @@ static int mt9m111_s_ctrl(struct v4l2_ctrl *ctrl)
>  					       struct mt9m111, hdl);
>  	int ret;
>
> +	if (!mt9m111->is_streaming)
> +		return 0;
> +
>  	switch (ctrl->id) {
>  	case V4L2_CID_VFLIP:
>  		ret = mt9m111_set_flip(mt9m111, ctrl->val,
> @@ -927,7 +934,6 @@ static int mt9m111_s_ctrl(struct v4l2_ctrl *ctrl)
>  		ret = -EINVAL;
>  	}
>
> -
>  	return ret;
>  }
>
> --
> 2.30.2
>