Re: [PATCH v3 9/9] media: subdev: Support single-stream case in v4l2_subdev_enable/disable_streams()

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]


Hi Tomi

On 11/04/24 5:23 pm, Tomi Valkeinen wrote:
On 11/04/2024 14:48, Umang Jain wrote:
Hi Tomi,

On 11/04/24 4:37 pm, Tomi Valkeinen wrote:
On 11/04/2024 14:02, Umang Jain wrote:
Hi Tomi,

On 10/04/24 6:05 pm, Tomi Valkeinen wrote:
At the moment the v4l2_subdev_enable/disable_streams() functions call
fallback helpers to handle the case where the subdev only implements
.s_stream(), and the main function handles the case where the subdev
implements streams (V4L2_SUBDEV_FL_STREAMS, which implies

What is missing is support for subdevs which do not implement streams
support, but do implement .enable/disable_streams(). Example cases of
these subdevices are single-stream cameras, where using
.enable/disable_streams() is not required but helps us remove the users of the legacy .s_stream(), and subdevices with multiple source pads (but
single stream per pad), where .enable/disable_streams() allows the
subdevice to control the enable/disable state per pad.

The two single-streams cases (.s_stream() and .enable/disable_streams())
are very similar, and with small changes we can change the
v4l2_subdev_enable/disable_streams() functions to support all three
cases, without needing separate fallback functions.

A few potentially problematic details, though:

Does this mean the patch needs to be worked upon more ?

I don't see the two issues below as blockers.

I quickly tested the series by applying it locally with my use case of IMX283 .enable/disable streams and s_stream as the helper function and it seems I am still seeing the same behaviour as before (i.e. not being streamed) and have to carry the workaround as mentioned in [1] **NOTE**

Ok... Then something bugs here, as it is supposed to fix the problem. Can you trace the code a bit to see where it goes wrong?

The execution should go to the "if (!(sd->flags & V4L2_SUBDEV_FL_STREAMS))" blocks in v4l2_subdev_collect_streams() and v4l2_subdev_set_streams_enabled(),

The execution is not reaching in v4l2_subdev_collect streams() even, it returns at

     if (!streams_mask)
                 return 0;

in v4l2_subdev_enable_streams()

Refer to :

My tree is based on v6.8 currently, but the series applies cleanly, so I have not introduced any  rebase artifacts. If you think, v6.8 might be causing issues, I'll then try to test on RPi 5 with the latest media tree perhaps.

So who is calling the v4l2_subdev_enable_streams? I presume it comes from v4l2_subdev_s_stream_helper(), in other words the sink side in your pipeline is using legacy s_stream?

Yes it comes from the helper function

static const struct v4l2_subdev_video_ops imx283_video_ops = {
        .s_stream = v4l2_subdev_s_stream_helper,

Indeed, that helper still needs work. It needs to detect if there's no routing, and use the implicit stream 0. I missed that one.

Yes, no routing in the driver.


[Index of Archives]     [Linux Input]     [Video for Linux]     [Gstreamer Embedded]     [Mplayer Users]     [Linux USB Devel]     [Linux Audio Users]     [Linux Kernel]     [Linux SCSI]     [Yosemite Backpacking]

  Powered by Linux