HID: support larger reports than 64 bytes in hiddev
hiddev userspace driver uses a rignbuffer to store the parsed usages that should be returned through read(). This buffer is 64 bytes long, which is sufficient for queueing single USB 1.0 low-speed report, which is of maximum size 48 bytes. There are however USB HID devices which are full-speed USB devices, and therefore they are free to produce reports 64 bytes long. This is correctly handled by HID core, but read() on hiddev node gets stuck forever, because the ring buffer loops infinitely (as it is exactly 64 bytes long as well), never advancing the buffer pointer. Plus, the core driver is ready to handle highspeed devices, so we should be able to handle reports from such devices in the hiddev driver as well, which means we need larger ringbuffer. Reported-by: Michael Zeisel <michael.zeisel@philips.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Showing
Please register or sign in to comment