linux-kernel - Re: [PATCH 1/1] media: v4l: Don't turn on privacy LED if streamon fails

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Date: Wed, 10 Apr 2024 11:31:47 +0000
From: Sakari Ailus <sakari.ailus@...ux.intel.com>
To: Hans de Goede <hdegoede@...hat.com>
Cc: linux-media@...r.kernel.org, tomi.valkeinen@...asonboard.com,
	Mauro Carvalho Chehab <mchehab@...nel.org>,
	Hans Verkuil <hverkuil@...all.nl>,
	Laurent Pinchart <laurent.pinchart@...asonboard.com>,
	Umang Jain <umang.jain@...asonboard.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] media: v4l: Don't turn on privacy LED if streamon
 fails

Hi Hans,

Thanks for the review.

On Wed, Apr 10, 2024 at 12:12:33PM +0200, Hans de Goede wrote:
> Hi Sakari,
> 
> Thank you for fixing this.
> 
> On 4/10/24 12:03 PM, Sakari Ailus wrote:
> > Turn on the privacy LED only if streamon succeeds. This can be done after
> > enabling streaming on the sensor.
> > 
> > Fixes: b6e10ff6c23d ("media: v4l2-core: Make the v4l2-core code enable/disable the privacy LED if present")
> > Signed-off-by: Sakari Ailus <sakari.ailus@...ux.intel.com>
> > ---
> >  drivers/media/v4l2-core/v4l2-subdev.c | 19 ++++++++++---------
> >  1 file changed, 10 insertions(+), 9 deletions(-)
> > 
> > diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
> > index 4c6198c48dd6..acb7c3003ab6 100644
> > --- a/drivers/media/v4l2-core/v4l2-subdev.c
> > +++ b/drivers/media/v4l2-core/v4l2-subdev.c
> > @@ -412,15 +412,6 @@ static int call_s_stream(struct v4l2_subdev *sd, int enable)
> >  	if (WARN_ON(!!sd->enabled_streams == !!enable))
> >  		return 0;
> >  
> > -#if IS_REACHABLE(CONFIG_LEDS_CLASS)
> > -	if (!IS_ERR_OR_NULL(sd->privacy_led)) {
> > -		if (enable)
> > -			led_set_brightness(sd->privacy_led,
> > -					   sd->privacy_led->max_brightness);
> > -		else
> > -			led_set_brightness(sd->privacy_led, 0);
> > -	}
> > -#endif
> >  	ret = sd->ops->video->s_stream(sd, enable);
> >  
> >  	if (!enable && ret < 0) {
> > @@ -431,6 +422,16 @@ static int call_s_stream(struct v4l2_subdev *sd, int enable)
> >  	if (!ret)
> >  		sd->enabled_streams = enable ? BIT(0) : 0;
> >  
> > +#if IS_REACHABLE(CONFIG_LEDS_CLASS)
> > +	if (!IS_ERR_OR_NULL(sd->privacy_led) && !(enable && ret < 0)) {
> 
> There already is a:
> 
> 	if (!enable && ret < 0)
> 		ret = 0;
> 
> block above to ignore stream-off errors, so you can just test for:
> 
> 	if (!ret && !IS_ERR_OR_NULL(sd->privacy_led)) {
> 		...
> 	}
> 
> And then you can move the whole block to inside the existing:
> 
> 	if (!ret)
> 		sd->enabled_streams = enable ? BIT(0) : 0;
> 
> block, so you get something like this:
> 
> 	if (!ret) {
> 		sd->enabled_streams = enable ? BIT(0) : 0;
> #if IS_REACHABLE(CONFIG_LEDS_CLASS)
> 		if (!IS_ERR_OR_NULL(sd->privacy_led)) {
> 			if (enable)
> 				led_set_brightness(sd->privacy_led,
> 						   sd->privacy_led->max_brightness);
> 			else
> 				led_set_brightness(sd->privacy_led, 0);
> 		}
> #endif
> 	}

Seems reasonable, I'll send v2.

> 
> Which then cleans up nicely by Tomi's patch
> introducing the privacy LED helper functions,
> to something like this:
> 
> 	if (!ret {
> 		if (enable) {
> 			sd->enabled_streams = BIT(0);
> 			v4l2_subdev_enable_privacy_led(sd);
> 		} else {
> 			sd->enabled_streams = 0;
> 			v4l2_subdev_disable_privacy_led(sd);
> 		}
> 	}
> 

-- 
Kind regards,

Sakari Ailus