This is a note to let you know that I've just added the patch titled
xhci: Don't clear hub TT buffer on ep0 protocol stall
to my usb git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git in the usb-linus branch.
The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)
The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.
If you have any questions about this process, please let me know.
From 8f97250c21f0cf36434bf5b7ddf4377406534cd1 Mon Sep 17 00:00:00 2001
From: Mathias Nyman mathias.nyman@linux.intel.com Date: Tue, 21 Apr 2020 17:08:22 +0300 Subject: xhci: Don't clear hub TT buffer on ep0 protocol stall
The default control endpoint ep0 can return a STALL indicating the device does not support the control transfer requests. This is called a protocol stall and does not halt the endpoint.
xHC behaves a bit different. Its internal endpoint state will always be halted on any stall, even if the device side of the endpiont is not halted. So we do need to issue the reset endpoint command to clear the xHC host intenal endpoint halt state, but should not request the HS hub to clear the TT buffer unless device side of endpoint is halted.
Clearing the hub TT buffer at protocol stall caused ep0 to become unresponsive for some FS/LS devices behind HS hubs, and class drivers failed to set the interface due to timeout:
usb 1-2.1: 1:1: usb_set_interface failed (-110)
Fixes: ef513be0a905 ("usb: xhci: Add Clear_TT_Buffer") Cc: stable@vger.kernel.org # v5.3 Signed-off-by: Mathias Nyman mathias.nyman@linux.intel.com Link: https://lore.kernel.org/r/20200421140822.28233-4-mathias.nyman@linux.intel.c... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/usb/host/xhci-ring.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-)
diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c index a7f4cd35da55..0fda0c0f4d31 100644 --- a/drivers/usb/host/xhci-ring.c +++ b/drivers/usb/host/xhci-ring.c @@ -1876,7 +1876,6 @@ static void xhci_cleanup_halted_endpoint(struct xhci_hcd *xhci, ep->ep_state |= EP_HARD_CLEAR_TOGGLE; xhci_cleanup_stalled_ring(xhci, slot_id, ep_index, stream_id, td); - xhci_clear_hub_tt_buffer(xhci, td, ep); } xhci_ring_cmd_db(xhci); } @@ -1997,11 +1996,18 @@ static int finish_td(struct xhci_hcd *xhci, struct xhci_td *td, if (trb_comp_code == COMP_STALL_ERROR || xhci_requires_manual_halt_cleanup(xhci, ep_ctx, trb_comp_code)) { - /* Issue a reset endpoint command to clear the host side - * halt, followed by a set dequeue command to move the - * dequeue pointer past the TD. - * The class driver clears the device side halt later. + /* + * xhci internal endpoint state will go to a "halt" state for + * any stall, including default control pipe protocol stall. + * To clear the host side halt we need to issue a reset endpoint + * command, followed by a set dequeue command to move past the + * TD. + * Class drivers clear the device side halt from a functional + * stall later. Hub TT buffer should only be cleared for FS/LS + * devices behind HS hubs for functional stalls. */ + if ((ep_index != 0) || (trb_comp_code != COMP_STALL_ERROR)) + xhci_clear_hub_tt_buffer(xhci, td, ep); xhci_cleanup_halted_endpoint(xhci, slot_id, ep_index, ep_ring->stream_id, td, EP_HARD_RESET); } else {