52302c30b2
[ Upstream commit d7428bc26fc767942c38d74b80299bcd4f01e7cb ]
f_hid provides the OUT Endpoint as only way for receiving reports
from the host. SETUP/SET_REPORT method is not supported, and this causes
a number of compatibility problems with various host drivers, especially
in the case of keyboard emulation using f_hid.
- Some hosts do not support the OUT Endpoint and ignore it,
so it becomes impossible for the gadget to receive a report
from the host. In the case of a keyboard, the gadget loses
the ability to receive the status of the LEDs.
- Some BIOSes/UEFIs can't work with HID devices with the OUT Endpoint
at all. This may be due to their bugs or incomplete implementation
of the HID standard.
For example, absolutely all Apple UEFIs can't handle the OUT Endpoint
if it goes after IN Endpoint in the descriptor and require the reverse
order (OUT, IN) which is a violation of the standard.
Other hosts either do not initialize gadgets with a descriptor
containing the OUT Endpoint completely (like some HP and DELL BIOSes
and embedded firmwares like on KVM switches), or initialize them,
but will not poll the IN Endpoint.
This patch adds configfs option no_out_endpoint=1 to disable
the OUT Endpoint and allows f_hid to receive reports from the host
via SETUP/SET_REPORT.
Previously, there was such a feature in f_hid, but it was replaced
by the OUT Endpoint [1] in the commit
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| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
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.