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commit2548288b4fupstream. It turns out that even though endpoints with a maxpacket length of 0 aren't useful for data transfer, the descriptors do serve other purposes. In particular, skipping them will also skip over other class-specific descriptors for classes such as UVC. This unexpected side effect has caused some UVC cameras to stop working. In addition, the USB spec requires that when isochronous endpoint descriptors are present in an interface's altsetting 0 (which is true on some devices), the maxpacket size _must_ be set to 0. Warning about such things seems like a bad idea. This patch updates an earlier commit which would log a warning and skip these endpoint descriptors. Now we only log a warning, and we don't even do that for isochronous endpoints in altsetting 0. We don't need to worry about preventing endpoints with maxpacket = 0 from ever being used for data transfers; usb_submit_urb() already checks for this. Reported-and-tested-by: Roger Whittaker <Roger.Whittaker@suse.com> Fixes:d482c7bb05("USB: Skip endpoints with 0 maxpacket length") Signed-off-by: Alan Stern <stern@rowland.harvard.edu> CC: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Link: https://marc.info/?l=linux-usb&m=157790377329882&w=2 Link: https://lore.kernel.org/r/Pine.LNX.4.44L0.2001061040270.1514-100000@iolanthe.rowland.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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.
See Documentation/00-INDEX for a list of what is contained in each file.
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.