Re: [PATCH v3 09/21] media: ipu6: Start streaming once all streams have started, stop when not

[Nicola Fiorillo <nicfio@gmail.com>]

Hi Sakari,

On Tue, Sep 22, 2026 at 03:05:26PM +0300, Sakari Ailus wrote:
> +static int ipu6_isys_csi2_streaming_change(struct ipu6_isys_subdev *asd,
> +					   struct v4l2_subdev_state *state,
> +					   u32 pad, u8 *vc, bool enable)

Thanks for picking up the return value and the inner loop key; both
read correctly to me in v3.

One question on the loop, again from reading only:

> +		struct media_pad *video_pad =
> +			media_pad_remote_pad_first(&asd->sd.entity.pads[route->source_pad]);
> +		struct ipu6_isys_video *av =
> +			container_of_const(video_pad, struct ipu6_isys_video,
> +					   pad);
> +
> +		streams_enabled++;
> +		if (av->streaming || (enable && pad == route->source_pad))

The CSI-2 source pad to video node links are created with no flags in
isys_csi2_create_media_links(), so they are neither immutable nor
enabled by default, and media_pad_remote_pad_first() returns NULL for a
pad whose link is disabled. With two active routes on the same virtual
channel, say one per source pad, and only one of the two video node
links enabled, streaming on the enabled node reaches the other route
here, and av->streaming is read through a pointer derived from NULL.

That does not need anything unusual: it is the multi-stream setup this
series prepares for, with one of the two outputs simply not in use.
Even without the oops, that route could never start streaming, so it
would hold back the first one forever.

Unless something earlier already rejects such a configuration and I
have missed it, skipping those routes would seem to cover both:

		if (!video_pad)
			continue;

Thanks,

--
Nicola Fiorillo