On Tue Sep 29 19:00:06 2026 -0700, Christopher Snowhill wrote:
> Commit 8e53399c63c3 ("media: em28xx: Add support for Empia em2828X
> bridge") changed the condition for setting V4L2_CAP_TUNER on the VBI
> device from "dev->tuner_type != TUNER_ABSENT" to a check of the video
> device's capabilities, but inverted it: the VBI node now advertises a
> tuner only when the video node does not have one.
>
> On boards without a tuner (e.g. the MyGica iGrabber, card=105) the VBI
> device's device_caps therefore contain V4L2_CAP_TUNER, while the shared
> vidioc_querycap() correctly omits it from cap->capabilities. This trips
> the sanity check in v4l_querycap() whenever the VBI node is queried,
> for example by udev's v4l_id on every hotplug:
>
> WARNING: drivers/media/v4l2-core/v4l2-ioctl.c:1119 at
> v4l_querycap+0xff/0x110 [videodev]
> (cap->capabilities & (vfd->device_caps | V4L2_CAP_DEVICE_CAPS)) !=
> (vfd->device_caps | V4L2_CAP_DEVICE_CAPS)
>
> It also leaves the tuner ioctls enabled on the VBI node of tuner-less
> boards and disables them on boards that do have a tuner.
>
> Restore the intended logic so the VBI device has V4L2_CAP_TUNER exactly
> when the video device does.
>
> Fixes: 8e53399c63c3 ("media: em28xx: Add support for Empia em2828X bridge")
> Assisted-by: LLM
> Signed-off-by: Christopher Snowhill <[email protected]>
> Cc: [email protected]
> Signed-off-by: Hans Verkuil <[email protected]>
Patch committed.
Thanks,
Hans Verkuil
drivers/media/usb/em28xx/em28xx-video.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/drivers/media/usb/em28xx/em28xx-video.c
b/drivers/media/usb/em28xx/em28xx-video.c
index a778bc4f61fb..a21ec2332dfb 100644
--- a/drivers/media/usb/em28xx/em28xx-video.c
+++ b/drivers/media/usb/em28xx/em28xx-video.c
@@ -3035,7 +3035,7 @@ static int em28xx_v4l2_init(struct em28xx *dev)
v4l2->vbi_dev.queue->lock = &v4l2->vb_vbi_queue_lock;
v4l2->vbi_dev.device_caps = V4L2_CAP_STREAMING |
V4L2_CAP_READWRITE | V4L2_CAP_VBI_CAPTURE;
- if ((v4l2->vdev.device_caps & V4L2_CAP_TUNER) == 0)
+ if (v4l2->vdev.device_caps & V4L2_CAP_TUNER)
v4l2->vbi_dev.device_caps |= V4L2_CAP_TUNER;
/* disable inapplicable ioctls */
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