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[ Upstream commit 4867bb590a ]
On a Webcam from Quanta, we see the following error.
usb 3-5: New USB device found, idVendor=0408, idProduct=30d2, bcdDevice= 0.03
usb 3-5: New USB device strings: Mfr=3, Product=1, SerialNumber=2
usb 3-5: Product: USB2.0 HD UVC WebCam
usb 3-5: Manufacturer: Quanta
usb 3-5: SerialNumber: 0x0001
...
uvcvideo: Found UVC 1.10 device USB2.0 HD UVC WebCam (0408:30d2)
uvcvideo: Failed to initialize entity for entity 5
uvcvideo: Failed to register entities (-22).
The Webcam reports an entity of type UVC_VC_EXTENSION_UNIT. It reports a
string index of '7' associated with that entity. The attempt to read that
string from the camera fails with error -32 (-EPIPE). usb_string() returns
that error, but it is ignored. As result, the entity name is empty. This
later causes v4l2_device_register_subdev() to return -EINVAL, and no
entities are registered as result.
While this appears to be a firmware problem with the camera, the kernel
should still handle the situation gracefully. To do that, check the return
value from usb_string(). If it reports an error, assign the entity's
default name.
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.