From: Alex He <alex.he@xxxxxxx>
xHCI 1.0 spec 4.6.8.1 describes Soft Retry mechanism.
A Soft Retry may effectively be used to recover from a USB Transaction Error
that was due to a temporary error condition. Oftern the delay introduced
between software detecting the error and attempting a Soft Retry is enough
to let the temporary condition clear and allow a successful transfer.
Signed-off-by: Alex He <alex.he@xxxxxxx>
Signed-off-by: Andiry Xu <andiry.xu@xxxxxxx>
---
drivers/usb/host/xhci-ring.c | 70 ++++++++++++++++++++++++++++++++++++++++++
drivers/usb/host/xhci.h | 6 +++
2 files changed, 76 insertions(+), 0 deletions(-)
diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index e07162d..d0b8c85 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -1645,6 +1645,18 @@ static int process_ctrl_td(struct xhci_hcd *xhci, struct xhci_td *td,
if (!xhci_requires_manual_halt_cleanup(xhci,
ep_ctx, trb_comp_code))
break;
+ if (trb_comp_code == COMP_TX_ERR &&
+ xhci->hci_version == 0x100) {
+ if (ep->soft_retries++ < SOFT_RETRY) {
+ xhci_soft_retry_ep(xhci, slot_id, ep_index,
+ ep_ring->stream_id, td,
+ event_trb);
+ return 0;
+ } else {
+ ep->soft_retries = 0;
+ }
+ }
+
xhci_dbg(xhci, "TRB error code %u, "
"halted endpoint index = %u\n",
trb_comp_code, ep_index);
@@ -1818,10 +1830,21 @@ static int process_bulk_intr_td(struct xhci_hcd *xhci, struct xhci_td *td,
union xhci_trb *event_trb, struct xhci_transfer_event *event,
struct xhci_virt_ep *ep, int *status)
{
+ struct xhci_virt_device *xdev;
+ unsigned int slot_id;
+ struct xhci_slot_ctx *slot_ctx;
+ int ep_index;
struct xhci_ring *ep_ring;
union xhci_trb *cur_trb;
struct xhci_segment *cur_seg;
u32 trb_comp_code;
+ u32 tt_hub_slot_id;
+
+ ep_index = TRB_TO_EP_ID(event->flags) - 1;
+ slot_id = TRB_TO_SLOT_ID(event->flags);
+ xdev = xhci->devs[slot_id];
+ slot_ctx = xhci_get_slot_ctx(xhci, xdev->out_ctx);
+ tt_hub_slot_id = slot_ctx->tt_info && 0xff;
ep_ring = xhci_dma_to_transfer_ring(ep, le64_to_cpu(event->buffer));
trb_comp_code = GET_COMP_CODE(le32_to_cpu(event->transfer_len));
@@ -1852,6 +1875,25 @@ static int process_bulk_intr_td(struct xhci_hcd *xhci, struct xhci_td *td,
else
*status = 0;
break;
+ case COMP_TX_ERR:
+ if (xhci->hci_version == 0x100) {
+ if (usb_endpoint_xfer_bulk(&td->urb->ep->desc) &&
+ (ep->soft_retries++ < SOFT_RETRY)) {
+ xhci_soft_retry_ep(xhci, slot_id, ep_index,
+ ep_ring->stream_id, td, event_trb);
+ return 0;
+
+ }
+ if (usb_endpoint_xfer_int(&td->urb->ep->desc) &&
+ tt_hub_slot_id == 0 &&
+ (ep->soft_retries++ < SOFT_RETRY)) {
+ xhci_soft_retry_ep(xhci, slot_id, ep_index,
+ ep_ring->stream_id, td, event_trb);
+ return 0;
+ }
+ ep->soft_retries = 0;
+ }
+ break;
default:
/* Others already handled above */
break;
@@ -3565,3 +3607,31 @@ int xhci_queue_reset_ep(struct xhci_hcd *xhci, int slot_id,
return queue_command(xhci, 0, 0, 0, trb_slot_id | trb_ep_index | type,
false);
}
+
+/*
+ * A Soft Retry may effectively be used to recver from a USB Transaction Error
+ * that was due to a temporary error codition. Details in the Chapter 4.6.8.1
+ * NOTE:
+ * 1. can't be called for isoc ep
+ * 2. can't be called for interrupt ep behind a TT
+ */
+void xhci_soft_retry_ep(struct xhci_hcd *xhci, int slot_id,
+ unsigned int ep_index, unsigned int stream_id,
+ struct xhci_td *td, union xhci_trb *event_trb)
+{
+ u32 trb_slot_id = SLOT_ID_FOR_TRB(slot_id);
+ u32 trb_ep_index = EP_ID_FOR_TRB(ep_index);
+ u32 type = TRB_TYPE(TRB_RESET_EP);
+ u32 tsp_flag = 1 << 9;
+ struct xhci_virt_ep *ep = &xhci->devs[slot_id]->eps[ep_index];
+
+ ep->ep_state |= EP_HALTED;
+ ep->stopped_td = td;
+ ep->stopped_trb = event_trb;
+ ep->stopped_stream = stream_id;
+
+ queue_command(xhci, 0, 0, 0,
+ trb_slot_id | trb_ep_index | type | tsp_flag, false);
+
+ xhci_ring_cmd_db(xhci);
+}
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index 33a49d5..dd45929 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -767,6 +767,9 @@ struct xhci_virt_ep {
* process the missed tds on the endpoint ring.
*/
bool skip;
+ /* Soft Retries to prevent an infinite loop */
+ unsigned int soft_retries;
+#define SOFT_RETRY 2
};
struct xhci_virt_device {
@@ -1540,6 +1543,9 @@ void xhci_queue_config_ep_quirk(struct xhci_hcd *xhci,
unsigned int slot_id, unsigned int ep_index,
struct xhci_dequeue_state *deq_state);
void xhci_stop_endpoint_command_watchdog(unsigned long arg);
+void xhci_soft_retry_ep(struct xhci_hcd *xhci, int slot_id,
+ unsigned int ep_index, unsigned int stream_id,
+ struct xhci_td *td, union xhci_trb *event_trb);
void xhci_ring_ep_doorbell(struct xhci_hcd *xhci, unsigned int slot_id,
unsigned int ep_index, unsigned int stream_id);
--
1.7.1
--
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