dwc_otg: use align_buf for small IN control transfers (#3150)
The hardware will do a 4-byte write to memory on any IN packet received that is between 1 and 3 bytes long. This tramples memory in the uvcvideo driver, as it uses a sequence of 1- and 2-byte control transfers to query the min/max/range/step of each individual camera control and gives us buffers that are offsets into a struct. Catch small control transfers in the data phase and use the align_buf to bounce the correct number of bytes into the URB's buffer. In general, short packets on non-control endpoints should be OK as URBs should have enough buffer space for a wMaxPacket size transfer. See: https://github.com/raspberrypi/linux/issues/3148 Signed-off-by:Jonathan Bell <jonathan@raspberrypi.org>
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