[PATCH 3/3] media: verisilicon: Allow the EOS event to be subscribed

hantro queues a V4L2_EVENT_EOS in three places.  vidioc_encoder_cmd()
sends it when a V4L2_ENC_CMD_STOP has drained the encoder:

	if (ec->cmd == V4L2_ENC_CMD_STOP &&
	    v4l2_m2m_has_stopped(ctx->fh.m2m_ctx))
		v4l2_event_queue_fh(&ctx->fh, &hantro_eos_event);

hantro_buf_queue() sends it for a capture buffer queued after the last
one, and hantro_stop_streaming() when the output queue stops while
draining.

No application can ask for any of them.  The ioctl ops offer

	.vidioc_subscribe_event = v4l2_ctrl_subscribe_event,

and v4l2_ctrl_subscribe_event() only knows about V4L2_EVENT_CTRL, so
VIDIOC_SUBSCRIBE_EVENT for V4L2_EVENT_EOS fails with -EINVAL and the
queued events are dropped on the floor.  An application following the
drain sequence in the stateful encoder documentation has to fall back to
V4L2_BUF_FLAG_LAST, which hantro does set, so this has gone unnoticed.

Dispatch on the event type and hand V4L2_EVENT_EOS to
v4l2_event_subscribe(), the way coda-common.c does.  Everything else
keeps going to the control handler.

V4L2_EVENT_SOURCE_CHANGE is deliberately not added, hantro never sends
one.

Fixes: daf3999c12dc ("media: hantro: Implement support for encoder commands")
Assisted-by: Claude:claude-opus-5
Signed-off-by: Sascha Hauer <[email protected]>
---
 drivers/media/platform/verisilicon/hantro_v4l2.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/media/platform/verisilicon/hantro_v4l2.c b/drivers/media/platform/verisilicon/hantro_v4l2.c
index 83af9fa1ce949..9e19daffe0075 100644
--- a/drivers/media/platform/verisilicon/hantro_v4l2.c
+++ b/drivers/media/platform/verisilicon/hantro_v4l2.c
@@ -765,6 +765,17 @@ static int vidioc_encoder_cmd(struct file *file, void *priv,
 	return 0;
 }
 
+static int hantro_subscribe_event(struct v4l2_fh *fh,
+				  const struct v4l2_event_subscription *sub)
+{
+	switch (sub->type) {
+	case V4L2_EVENT_EOS:
+		return v4l2_event_subscribe(fh, sub, 0, NULL);
+	default:
+		return v4l2_ctrl_subscribe_event(fh, sub);
+	}
+}
+
 const struct v4l2_ioctl_ops hantro_ioctl_ops = {
 	.vidioc_querycap = vidioc_querycap,
 	.vidioc_enum_framesizes = vidioc_enum_framesizes,
@@ -787,7 +798,7 @@ const struct v4l2_ioctl_ops hantro_ioctl_ops = {
 	.vidioc_remove_bufs = v4l2_m2m_ioctl_remove_bufs,
 	.vidioc_expbuf = v4l2_m2m_ioctl_expbuf,
 
-	.vidioc_subscribe_event = v4l2_ctrl_subscribe_event,
+	.vidioc_subscribe_event = hantro_subscribe_event,
 	.vidioc_unsubscribe_event = v4l2_event_unsubscribe,
 
 	.vidioc_streamon = v4l2_m2m_ioctl_streamon,

-- 
2.47.3