linux-kernel - Re: [PATCH v3 7/9] media: subdev: Support privacy led in v4l2_subdev_enable/disable

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Message-ID: <20240419102211.GA2604@pendragon.ideasonboard.com>
Date: Fri, 19 Apr 2024 13:22:11 +0300
From: Laurent Pinchart <laurent.pinchart@...asonboard.com>
To: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
Cc: Mauro Carvalho Chehab <mchehab@...nel.org>,
	Hans Verkuil <hverkuil@...all.nl>,
	Sakari Ailus <sakari.ailus@...ux.intel.com>,
	Umang Jain <umang.jain@...asonboard.com>,
	linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 7/9] media: subdev: Support privacy led in
 v4l2_subdev_enable/disable_streams()

On Tue, Apr 16, 2024 at 01:34:22PM +0300, Tomi Valkeinen wrote:
> On 12/04/2024 21:20, Laurent Pinchart wrote:
> > Hi Tomi,
> > 
> > Thank you for the patch.
> > 
> > On Wed, Apr 10, 2024 at 03:35:54PM +0300, Tomi Valkeinen wrote:
> >> We support camera privacy leds with the .s_stream, in call_s_stream, but
> > 
> > s/the .s_stream/the .s_stream() operation/
> > 
> >> we don't have that support when the subdevice implements
> >> .enable/disable_streams.
> >>
> >> Add the support by enabling the led when the first stream for a
> >> subdevice is enabled, and disabling the led then the last stream is
> >> disabled.
> > 
> > I wonder if that will always be the correct constraint for all devices,
> > but I suppose we can worry about it later.
> > 
> >> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
> >> ---
> >>   drivers/media/v4l2-core/v4l2-subdev.c | 9 +++++++++
> >>   1 file changed, 9 insertions(+)
> >>
> >> diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
> >> index 20b5a00cbeeb..f44aaa4e1fab 100644
> >> --- a/drivers/media/v4l2-core/v4l2-subdev.c
> >> +++ b/drivers/media/v4l2-core/v4l2-subdev.c
> >> @@ -2150,6 +2150,7 @@ int v4l2_subdev_enable_streams(struct v4l2_subdev *sd, u32 pad,
> >>   {
> >>   	struct device *dev = sd->entity.graph_obj.mdev->dev;
> >>   	struct v4l2_subdev_state *state;
> >> +	bool already_streaming;
> >>   	u64 found_streams = 0;
> >>   	unsigned int i;
> >>   	int ret;
> >> @@ -2198,6 +2199,8 @@ int v4l2_subdev_enable_streams(struct v4l2_subdev *sd, u32 pad,
> >>   
> >>   	dev_dbg(dev, "enable streams %u:%#llx\n", pad, streams_mask);
> >>   
> >> +	already_streaming = v4l2_subdev_is_streaming(sd);
> >> +
> >>   	/* Call the .enable_streams() operation. */
> >>   	ret = v4l2_subdev_call(sd, pad, enable_streams, state, pad,
> >>   			       streams_mask);
> >> @@ -2216,6 +2219,9 @@ int v4l2_subdev_enable_streams(struct v4l2_subdev *sd, u32 pad,
> >>   			cfg->enabled = true;
> >>   	}
> >>   
> >> +	if (!already_streaming)
> >> +		v4l2_subdev_enable_privacy_led(sd);
> >> +
> >>   done:
> >>   	v4l2_subdev_unlock_state(state);
> >>   
> >> @@ -2340,6 +2346,9 @@ int v4l2_subdev_disable_streams(struct v4l2_subdev *sd, u32 pad,
> >>   	}
> >>   
> >>   done:
> >> +	if (!v4l2_subdev_is_streaming(sd))
> > 
> > Wouldn't it be more efficient to check this while looping over the
> > stream configs in the loop just above ? Same for
> > v4l2_subdev_enable_streams().
> 
> It would, but it would get a lot messier to manage with "media: subdev: 
> Refactor v4l2_subdev_enable/disable_streams()", and we would also need 
> to support the non-routing case.

True.

> This is usually a loop with a couple of iterations, and only called when 
> enabling or enabling a subdevice, so I'm not really worried about the 
> performance. If it's an issue, it would probably be better to also 
> update the sd->enabled_pads when enabling/disabling a stream.

OK, I can live with that for now.

-- 
Regards,

Laurent Pinchart