libpayload: xhci: Ensure to reset dequeue pointer on stopped endpoints
This patch fixes a bug in the XHCI stack that occurs when a multi-TRB TD
times out before the last TRB is processed. The driver will correctly
issue a Stop Endpoint command in that case, but the xHC will still
preserve the transfer state and just pick up right after that on the
next doorbell ring. It will then process the leftover TRBs from the old
TD the next time a transfer is issued. (cf. XHCI 4.6.9)
We fix this by changing the existing xhci_reset_endpoint() calls in
transfer functions to not only trigger on Halted (2) and Error (4), but
also on Stopped (3). That function will not actually issue a Reset
Endpoint command in this case, but it will nuke the whole transfer ring
and issue a Set TR Dequeue Pointer command, which is sufficient (though
slightly overkill) to solve our problem.
BUG=chrome-os-partner:21969
TEST=Manual
Change-Id: I3abbe30ff9d4911a8af1f792324e018d427019e8
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/170833
Reviewed-by: Ronald Minnich <rminnich@chromium.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
1 file changed
