| Message ID | 20250310094037.52625e24@foxbook (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [1/6] usb: xhci: Document endpoint state management | expand |
On 10.3.2025 10.40, Michal Pecio wrote: > When the device stalls an endpoint, current TD is assigned -EPIPE > status and Reset Endpoint is queued. If a Stop Endpoint is pending > at the time, it will run before Reset Endpoint and fail due to the > stall. Its handler will change TD's status to -EPROTO before Reset > Endpoint handler runs and initiates giveback. > > Check if the stall has already been handled and don't try to do it > again. Since xhci_handle_halted_endpoint() performs this check too, > not overwriting td->status is the only difference. > > I haven't seen this case yet, but I have seen a related one where > the xHC has already executed Reset Endpoint, EP Context state is > now Stopped and EP_HALTED is set. If the xHC took a bit longer to > execute Reset Endpoint, said case would become this one. > > Signed-off-by: Michal Pecio <michal.pecio@gmail.com> Makes sense, nice improvement Thanks Mathias
diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c index 9e4940220252..28ebc0fc5bc2 100644 --- a/drivers/usb/host/xhci-ring.c +++ b/drivers/usb/host/xhci-ring.c @@ -1215,7 +1215,14 @@ static void xhci_handle_cmd_stop_ep(struct xhci_hcd *xhci, int slot_id, */ switch (GET_EP_CTX_STATE(ep_ctx)) { case EP_STATE_HALTED: - xhci_dbg(xhci, "Stop ep completion raced with stall, reset ep\n"); + xhci_dbg(xhci, "Stop ep completion raced with stall\n"); + /* + * If the halt happened before Stop Endpoint failed, its transfer event + * should have already been handled and Reset Endpoint should be pending. + */ + if (ep->ep_state & EP_HALTED) + goto reset_done; + if (ep->ep_state & EP_HAS_STREAMS) { reset_type = EP_SOFT_RESET; } else { @@ -1226,8 +1233,11 @@ static void xhci_handle_cmd_stop_ep(struct xhci_hcd *xhci, int slot_id, } /* reset ep, reset handler cleans up cancelled tds */ err = xhci_handle_halted_endpoint(xhci, ep, td, reset_type); + xhci_dbg(xhci, "Stop ep completion resetting ep, status %d\n", err); if (err) break; +reset_done: + /* Reset EP handler will clean up cancelled TDs */ ep->ep_state &= ~EP_STOP_CMD_PENDING; return; case EP_STATE_STOPPED:
When the device stalls an endpoint, current TD is assigned -EPIPE status and Reset Endpoint is queued. If a Stop Endpoint is pending at the time, it will run before Reset Endpoint and fail due to the stall. Its handler will change TD's status to -EPROTO before Reset Endpoint handler runs and initiates giveback. Check if the stall has already been handled and don't try to do it again. Since xhci_handle_halted_endpoint() performs this check too, not overwriting td->status is the only difference. I haven't seen this case yet, but I have seen a related one where the xHC has already executed Reset Endpoint, EP Context state is now Stopped and EP_HALTED is set. If the xHC took a bit longer to execute Reset Endpoint, said case would become this one. Signed-off-by: Michal Pecio <michal.pecio@gmail.com> --- drivers/usb/host/xhci-ring.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-)