On Thu, Oct 25, 2018 at 4:30 PM Stefan Wahren <stefan.wahren@xxxxxxxx> wrote:
>
> Abort the probing of the camera driver in case there isn't a camera
> actually connected to the Raspberry Pi. This solution also avoids a
> NULL ptr dereference of mmal instance on driver unload.
>
> Fixes: 7b3ad5abf027 ("staging: Import the BCM2835 MMAL-based V4L2 camera driver.")
> Signed-off-by: Stefan Wahren <stefan.wahren@xxxxxxxx>
Tested-by: Peter Robinson <pbrobinson@xxxxxxxxx>
In testing this both with and without a camera module attached it
appears to still load the entire v4l stack even if there's no camera
attached and it remains post probe, the /dev/video0 interface doesn't
appear, which is what I'd expect, and from the dmesg output
with/without a camera module it certainly seems to do less. I'm not
sure if it's possible to detect whether we have a camera module before
we start up the full media/v4l stack and exit the process and unload
the module but I suspect having all the v4l bits loaded without
various interfaces might cause confusion.
# lsmod| grep v4l
bcm2835_v4l2 61440 0
videobuf2_vmalloc 20480 1 bcm2835_v4l2
videobuf2_v4l2 24576 1 bcm2835_v4l2
videobuf2_common 49152 2 bcm2835_v4l2,videobuf2_v4l2
v4l2_common 16384 1 bcm2835_v4l2
videodev 180224 4
v4l2_common,videobuf2_common,bcm2835_v4l2,videobuf2_v4l2
media 49152 3 videobuf2_common,videodev,videobuf2_v4l2
vchiq 237568 2 bcm2835_v4l2,snd_bcm2835
Peter
> ---
> drivers/staging/vc04_services/bcm2835-camera/bcm2835-camera.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/drivers/staging/vc04_services/bcm2835-camera/bcm2835-camera.c b/drivers/staging/vc04_services/bcm2835-camera/bcm2835-camera.c
> index c04bdf0..d6fbef7 100644
> --- a/drivers/staging/vc04_services/bcm2835-camera/bcm2835-camera.c
> +++ b/drivers/staging/vc04_services/bcm2835-camera/bcm2835-camera.c
> @@ -1841,6 +1841,12 @@ static int bcm2835_mmal_probe(struct platform_device *pdev)
> num_cameras = get_num_cameras(instance,
> resolutions,
> MAX_BCM2835_CAMERAS);
> +
> + if (num_cameras < 1) {
> + ret = -ENODEV;
> + goto cleanup_mmal;
> + }
> +
> if (num_cameras > MAX_BCM2835_CAMERAS)
> num_cameras = MAX_BCM2835_CAMERAS;
>
> @@ -1940,6 +1946,9 @@ static int bcm2835_mmal_probe(struct platform_device *pdev)
> pr_info("%s: error %d while loading driver\n",
> BM2835_MMAL_MODULE_NAME, ret);
>
> +cleanup_mmal:
> + vchiq_mmal_finalise(instance);
> +
> return ret;
> }
>
> --
> 2.7.4
>
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