xhci: add helper to stop endpoint and wait for completion

Expose xhci_stop_endpoint_sync() which is a synchronous variant of
xhci_queue_stop_endpoint().  This is useful for client drivers that are
using the secondary interrupters, and need to stop the current endpoint
session.

This does not go through the normal xhci_handle_cmd_stop_ep() command
completion handler, because it utilizes the completion path to achieve
synchronous behavior.  Users of this API are primarily intended to be
clients that maintain their own transfer rings, such as in the case of USB
audio offload.

Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Wesley Cheng <quic_wcheng@quicinc.com>
Link: https://lore.kernel.org/r/20241015212915.1206789-3-quic_wcheng@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 899c0effb5d3c16db0b8bf321b9666e6ae5c11fa..fdb1b71eeec265d81e7938f965887aa1b6ff5412 100644 (file)
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -2794,6 +2794,51 @@ static int xhci_reserve_bandwidth(struct xhci_hcd *xhci,
        return -ENOMEM;
 }
 
+/*
+ * Synchronous XHCI stop endpoint helper.  Issues the stop endpoint command and
+ * waits for the command completion before returning.  This does not call
+ * xhci_handle_cmd_stop_ep(), which has additional handling for 'context error'
+ * cases, along with transfer ring cleanup.
+ *
+ * xhci_stop_endpoint_sync() is intended to be utilized by clients that manage
+ * their own transfer ring, such as offload situations.
+ */
+int xhci_stop_endpoint_sync(struct xhci_hcd *xhci, struct xhci_virt_ep *ep, int suspend,
+                           gfp_t gfp_flags)
+{
+       struct xhci_command *command;
+       unsigned long flags;
+       int ret;
+
+       command = xhci_alloc_command(xhci, true, gfp_flags);
+       if (!command)
+               return -ENOMEM;
+
+       spin_lock_irqsave(&xhci->lock, flags);
+       ret = xhci_queue_stop_endpoint(xhci, command, ep->vdev->slot_id,
+                                      ep->ep_index, suspend);
+       if (ret < 0) {
+               spin_unlock_irqrestore(&xhci->lock, flags);
+               goto out;
+       }
+
+       xhci_ring_cmd_db(xhci);
+       spin_unlock_irqrestore(&xhci->lock, flags);
+
+       wait_for_completion(command->completion);
+
+       /* No handling for COMP_CONTEXT_STATE_ERROR done at command completion*/
+       if (command->status == COMP_COMMAND_ABORTED ||
+           command->status == COMP_COMMAND_RING_STOPPED) {
+               xhci_warn(xhci, "Timeout while waiting for stop endpoint command\n");
+               ret = -ETIME;
+       }
+out:
+       xhci_free_command(xhci, command);
+
+       return ret;
+}
+EXPORT_SYMBOL_GPL(xhci_stop_endpoint_sync);
 
 /* Issue a configure endpoint command or evaluate context command
  * and wait for it to finish.

diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index 620502de971a435b76e37d53ef1c0e6ff7c2e771..529213ceb9fd2cfd650bfc9821ac16a8c6413b69 100644 (file)
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -1913,6 +1913,8 @@ void xhci_ring_doorbell_for_active_rings(struct xhci_hcd *xhci,
 void xhci_cleanup_command_queue(struct xhci_hcd *xhci);
 void inc_deq(struct xhci_hcd *xhci, struct xhci_ring *ring);
 unsigned int count_trbs(u64 addr, u64 len);
+int xhci_stop_endpoint_sync(struct xhci_hcd *xhci, struct xhci_virt_ep *ep,
+                           int suspend, gfp_t gfp_flags);
 
 /* xHCI roothub code */
 void xhci_set_link_state(struct xhci_hcd *xhci, struct xhci_port *port,