linux-kernel - Re: [PATCH v2 3/3] media: mt9m111: don't turn on the output while powering it

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Message-ID: <Yyhn68RabEvVXu+S@pendragon.ideasonboard.com>
Date:   Mon, 19 Sep 2022 16:00:27 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Marco Felsch <m.felsch@...gutronix.de>
Cc:     mchehab@...nel.org, sakari.ailus@...ux.intel.com,
        akinobu.mita@...il.com, jacopo+renesas@...ndi.org,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/3] media: mt9m111: don't turn on the output while
 powering it

Hi Marco,

Thank you for the patch.

On Fri, Sep 16, 2022 at 03:57:13PM +0200, Marco Felsch wrote:
> Currently the .s_power() turn on/off the device and enables/disables the
> sensor output. This is wrong since it should only handle the power not
> not the sensor output behaviour. Enabling the sensor output should be
> part of the .s_stream() callback.
> 
> Fix this by adding mt9m111_set_output() which gets called by the
> .s_stream() callback and remove the output register bits from
> mt9m111_resume/suspend.
> 
> Signed-off-by: Marco Felsch <m.felsch@...gutronix.de>
> ---
> Changelog:
> 
> v2:
> - new patch, replaces: "media: mt9m111: remove .s_power callback"
> ---
>  drivers/media/i2c/mt9m111.c | 38 ++++++++++++++++++++++++++-----------
>  1 file changed, 27 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/media/i2c/mt9m111.c b/drivers/media/i2c/mt9m111.c
> index 8de93ab99cbc..2cc0b0da7636 100644
> --- a/drivers/media/i2c/mt9m111.c
> +++ b/drivers/media/i2c/mt9m111.c
> @@ -426,10 +426,25 @@ static int mt9m111_setup_geometry(struct mt9m111 *mt9m111, struct v4l2_rect *rec
>  	return ret;
>  }
>  
> -static int mt9m111_enable(struct mt9m111 *mt9m111)
> +static int mt9m111_set_output(struct mt9m111 *mt9m111, int on)
>  {
>  	struct i2c_client *client = v4l2_get_subdevdata(&mt9m111->subdev);
> -	return reg_write(RESET, MT9M111_RESET_CHIP_ENABLE);
> +	int ret;
> +
> +	if (on) {
> +		ret = reg_clear(RESET, MT9M111_RESET_OUTPUT_DISABLE);
> +		if (ret)
> +			return ret;
> +
> +		return reg_set(RESET, MT9M111_RESET_CHIP_ENABLE);
> +	}
> +
> +	/* disable */
> +	ret = reg_set(RESET, MT9M111_RESET_OUTPUT_DISABLE);
> +	if (ret)
> +		return ret;
> +
> +	return reg_clear(RESET, MT9M111_RESET_CHIP_ENABLE);

Unless the hardware specifically requires this sequence, I'd use the
inverse of the enable sequence here.

Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>

>  }
>  
>  static int mt9m111_reset(struct mt9m111 *mt9m111)
> @@ -927,10 +942,7 @@ static int mt9m111_suspend(struct mt9m111 *mt9m111)
>  	ret = reg_set(RESET, MT9M111_RESET_RESET_MODE);
>  	if (!ret)
>  		ret = reg_set(RESET, MT9M111_RESET_RESET_SOC |
> -			      MT9M111_RESET_OUTPUT_DISABLE |
>  			      MT9M111_RESET_ANALOG_STANDBY);
> -	if (!ret)
> -		ret = reg_clear(RESET, MT9M111_RESET_CHIP_ENABLE);
>  
>  	return ret;
>  }
> @@ -951,9 +963,9 @@ static void mt9m111_restore_state(struct mt9m111 *mt9m111)
>  
>  static int mt9m111_resume(struct mt9m111 *mt9m111)
>  {
> -	int ret = mt9m111_enable(mt9m111);
> -	if (!ret)
> -		ret = mt9m111_reset(mt9m111);
> +	int ret;
> +
> +	ret = mt9m111_reset(mt9m111);
>  	if (!ret)
>  		mt9m111_restore_state(mt9m111);
>  
> @@ -965,9 +977,7 @@ static int mt9m111_init(struct mt9m111 *mt9m111)
>  	struct i2c_client *client = v4l2_get_subdevdata(&mt9m111->subdev);
>  	int ret;
>  
> -	ret = mt9m111_enable(mt9m111);
> -	if (!ret)
> -		ret = mt9m111_reset(mt9m111);
> +	ret = mt9m111_reset(mt9m111);
>  	if (!ret)
>  		ret = mt9m111_set_context(mt9m111, mt9m111->ctx);
>  	if (ret)
> @@ -1116,8 +1126,14 @@ 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;
> +
> +	ret = mt9m111_set_output(mt9m111, enable);
> +	if (ret)
> +		return ret;
>  
>  	mt9m111->is_streaming = !!enable;
> +
>  	return 0;
>  }
>  

-- 
Regards,

Laurent Pinchart