[PATCH] video: fbdev: imxfb: ensure balanced regulator usage

[Bartlomiej Zolnierkiewicz]

On 3/23/20 10:16 PM, Uwe Kleine-König wrote:
> The fbdev framework doesn't care to call the .set_power callback only on
> changes. So the driver has to care for itself that the regulator doesn't
> get disabled more often than enabled.
> 
> This fixes the regulator warning
> 
> 	unbalanced disables for lcd supply
> 
> which can be triggered by doing
> 
> 	echo 4 > /sys/class/lcd/imxfb-lcd/lcd_power
> 
> twice.
> 
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig at pengutronix.de>

Patch queued for v5.8, thanks.

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics

> ---
>  drivers/video/fbdev/imxfb.c | 27 +++++++++++++++++++++------
>  1 file changed, 21 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/video/fbdev/imxfb.c b/drivers/video/fbdev/imxfb.c
> index 370bf2553d43..884b16efa7e8 100644
> --- a/drivers/video/fbdev/imxfb.c
> +++ b/drivers/video/fbdev/imxfb.c
> @@ -172,6 +172,7 @@ struct imxfb_info {
>  	int			num_modes;
>  
>  	struct regulator	*lcd_pwr;
> +	int			lcd_pwr_enabled;
>  };
>  
>  static const struct platform_device_id imxfb_devtype[] = {
> @@ -801,16 +802,30 @@ static int imxfb_lcd_get_power(struct lcd_device *lcddev)
>  	return FB_BLANK_UNBLANK;
>  }
>  
> +static int imxfb_regulator_set(struct imxfb_info *fbi, int enable)
> +{
> +	int ret;
> +
> +	if (enable == fbi->lcd_pwr_enabled)
> +		return 0;
> +
> +	if (enable)
> +		ret = regulator_enable(fbi->lcd_pwr);
> +	else
> +		ret = regulator_disable(fbi->lcd_pwr);
> +
> +	if (ret == 0)
> +		fbi->lcd_pwr_enabled = enable;
> +
> +	return ret;
> +}
> +
>  static int imxfb_lcd_set_power(struct lcd_device *lcddev, int power)
>  {
>  	struct imxfb_info *fbi = dev_get_drvdata(&lcddev->dev);
>  
> -	if (!IS_ERR(fbi->lcd_pwr)) {
> -		if (power == FB_BLANK_UNBLANK)
> -			return regulator_enable(fbi->lcd_pwr);
> -		else
> -			return regulator_disable(fbi->lcd_pwr);
> -	}
> +	if (!IS_ERR(fbi->lcd_pwr))
> +		return imxfb_regulator_set(fbi, power == FB_BLANK_UNBLANK);
>  
>  	return 0;
>  }
>