[PATCH] libcamera: device_enumerator: exclude uvcvideo device when enumerate

[Jacopo Mondi]

Hi Anle

On Tue, Mar 26, 2024 at 05:38:04PM +0900, Anle Pan wrote:
> Camera service startup crash when camera and
> usb camera are connected at the same time,
> service will always reboot due to the null pointer
> in populateEntities.

This is weird, libcamera has been used with uvcvideo devices since the
very beginning. As far as I understand, this is not related to Android
or its CameraService, right ? Just loading the library fails ?

>
> In this case, a UVC device was used to populate the
> related entities, pads and links, which was not reasonable.

Not a UVC expert, but why this is not reasonable ? uvc devices have a
media graph with entities, links and pads like every other device,
don't they ?

>
> To fix the issue, ensure the media node is not
> a "uvcvideo" device when enumerate before createDevice.

So this is disabling uvc support in libcamera completely, preventing
uvcvideo devices from being enumerated ?

What about uvcvideo users ? :)

>
> Change-Id: I656a542e83449df287d34a4e358ae2e26e784f17
> Signed-off-by: Anle Pan <anle.pan at nxp.com>
> ---
>  src/libcamera/device_enumerator_sysfs.cpp | 21 +++++++++++++++++++++
>  1 file changed, 21 insertions(+)
>
> diff --git a/src/libcamera/device_enumerator_sysfs.cpp b/src/libcamera/device_enumerator_sysfs.cpp
> index 9979d68a..224ec8c8 100644
> --- a/src/libcamera/device_enumerator_sysfs.cpp
> +++ b/src/libcamera/device_enumerator_sysfs.cpp
> @@ -73,6 +73,27 @@ int DeviceEnumeratorSysfs::enumerate()
>  			continue;
>  		}
>
> +		/* Check that the device node not a uvcvideo. */
> +		struct media_device_info devinfo;
> +		int fd = open(devnode.c_str(), O_RDWR | O_CLOEXEC);
> +		if (fd < 0) {
> +			LOG(DeviceEnumerator, Warning)
> +				<< "Failed to open media device:" + devnode
> +				<< " (" << strerror(errno) << "), skipping";
> +			continue;
> +		}
> +		int retval = ioctl(fd, MEDIA_IOC_DEVICE_INFO, &devinfo);
> +		close(fd);
> +		if (retval != 0) {
> +			LOG(DeviceEnumerator, Warning)
> +				<< "Failed to get info from device:" + devnode
> +				<< " (" << strerror(errno) << "), skipping";
> +			continue;
> +		}
> +		if (strstr("uvcvideo", devinfo.driver)) {
> +			continue;
> +		}
> +
>  		std::unique_ptr<MediaDevice> media = createDevice(devnode);
>  		if (!media)
>  			continue;
> --
> 2.34.1
>