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| H A D | gs_usb.c | diff 1cdd3563e147ba1911da6720069ab473b1c69272 Fri Oct 18 16:24:26 CDT 2024 Alexander Kozhinov <ak.alexander.kozhinov@gmail.com> can: gs_usb: add usb endpoint address detection at driver probe step
[ Upstream commit 889b2ae9139a87b3390f7003cb1bb3d65bf90a26 ]
There is an approach made to implement gs_usb firmware/driver based on
Zephyr RTOS. It was found that USB stack of Zephyr RTOS overwrites USB
EP addresses, if they have different last 4 bytes in absence of other
endpoints.
For example in case of gs_usb candlelight firmware EP-IN is 0x81 and
EP-OUT 0x02. If there are no additional USB endpoints, Zephyr RTOS will
overwrite EP-OUT to 0x01. More information can be found in the
discussion with Zephyr RTOS USB stack maintainer here:
https://github.com/zephyrproject-rtos/zephyr/issues/67812
There are already two different gs_usb FW driver implementations based
on Zephyr RTOS:
1. https://github.com/CANnectivity/cannectivity
(by: https://github.com/henrikbrixandersen)
2. https://github.com/zephyrproject-rtos/zephyr/compare/main...KozhinovAlexander:zephyr:gs_usb
(by: https://github.com/KozhinovAlexander)
At the moment both Zephyr RTOS implementations use dummy USB endpoint,
to overcome described USB stack behavior from Zephyr itself. Since
Zephyr RTOS is intended to be used on microcontrollers with very
constrained amount of resources (ROM, RAM) and additional endpoint
requires memory, it is more convenient to update the gs_usb driver in
the Linux kernel.
To fix this problem, update the gs_usb driver from using hard coded
endpoint numbers to evaluate the endpoint descriptors and use the
endpoints provided there.
Fixes: d08e973a77d1 ("can: gs_usb: Added support for the GS_USB CAN devices")
Reviewed-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: Alexander Kozhinov <ak.alexander.kozhinov@gmail.com>
Link: https://patch.msgid.link/20241018212450.31746-1-ak.alexander.kozhinov@gmail.com
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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