xhci: Reset reserved command ring TRBs on cleanup.

commit 33b2831ac870d50cc8e01c317b07fb1e69c13fe1 upstream.

When the xHCI driver needs to clean up memory (perhaps due to a failed
register restore on resume from S3 or resume from S4), it needs to reset
the number of reserved TRBs on the command ring to zero.  Otherwise,
several resume cycles (about 30) with a UAS device attached will
continually increment the number of reserved TRBs, until all command
submissions fail because there isn't enough room on the command ring.

This patch should be backported to kernels as old as 2.6.32,
that contain the commit 913a8a344ffcaf0b4a586d6662a2c66a7106557d
"USB: xhci: Change how xHCI commands are handled."

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
index 68eaa908ac8eaa10eca2e1d9a6a9573b14efd5a0..3c9bb3db8eccaa8757354fd2114d09c2c0b2573b 100644 (file)
--- a/drivers/usb/host/xhci-mem.c
+++ b/drivers/usb/host/xhci-mem.c
@@ -1807,6 +1807,7 @@ void xhci_mem_cleanup(struct xhci_hcd *xhci)
        xhci->event_ring = NULL;
        xhci_dbg(xhci, "Freed event ring\n");
 
+       xhci->cmd_ring_reserved_trbs = 0;
        if (xhci->cmd_ring)
                xhci_ring_free(xhci, xhci->cmd_ring);
        xhci->cmd_ring = NULL;