Use soft retry to recover from a USB Transaction Errors that are caused by
temporary error conditions. The USB device is not aware that the xHC
has halted the endpoint, and will be waiting for another retry
A Soft Retry perform additional retries and recover from an error which has
caused the xHC to halt an endpoint.
Soft retry has some limitations:
Soft Retry attempts shall not be performed on Isoch endpoints
Soft Retry attempts shall not be performed if the device is behind a TT in
a HS Hub
Software shall limit the number of unsuccessful Soft Retry attempts to
prevent an infinite loop.
For more details on Soft retry see xhci specs 4.6.8.1
Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
---
drivers/usb/host/xhci-ring.c | 19 +++++++++++++++++++
drivers/usb/host/xhci.h | 2 ++
2 files changed, 21 insertions(+)
diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index f0a99aa..c41341e 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -1155,6 +1155,10 @@ static void xhci_handle_cmd_reset_ep(struct xhci_hcd *xhci, int slot_id,
/* Clear our internal halted state */
xhci->devs[slot_id]->eps[ep_index].ep_state &= ~EP_HALTED;
}
+
+ /* if this was a soft reset, then restart */
+ if ((le32_to_cpu(trb->generic.field[3])) & TRB_TSP)
+ ring_doorbell_for_active_rings(xhci, slot_id, ep_index);
}
static void xhci_handle_cmd_enable_slot(struct xhci_hcd *xhci, int slot_id,
@@ -2132,10 +2136,16 @@ static int process_bulk_intr_td(struct xhci_hcd *xhci, struct xhci_td *td,
union xhci_trb *ep_trb, struct xhci_transfer_event *event,
struct xhci_virt_ep *ep, int *status)
{
+ struct xhci_slot_ctx *slot_ctx;
struct xhci_ring *ep_ring;
u32 trb_comp_code;
u32 remaining, requested, ep_trb_len;
+ unsigned int slot_id;
+ int ep_index;
+ slot_id = TRB_TO_SLOT_ID(le32_to_cpu(event->flags));
+ slot_ctx = xhci_get_slot_ctx(xhci, xhci->devs[slot_id]->out_ctx);
+ ep_index = TRB_TO_EP_ID(le32_to_cpu(event->flags)) - 1;
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));
remaining = EVENT_TRB_LEN(le32_to_cpu(event->transfer_len));
@@ -2144,6 +2154,7 @@ static int process_bulk_intr_td(struct xhci_hcd *xhci, struct xhci_td *td,
switch (trb_comp_code) {
case COMP_SUCCESS:
+ ep_ring->err_count = 0;
/* handle success with untransferred data as short packet */
if (ep_trb != td->last_trb || remaining) {
xhci_warn(xhci, "WARN Successful completion on short TX\n");
@@ -2167,6 +2178,14 @@ static int process_bulk_intr_td(struct xhci_hcd *xhci, struct xhci_td *td,
ep_trb_len = 0;
remaining = 0;
break;
+ case COMP_USB_TRANSACTION_ERROR:
+ if ((ep_ring->err_count++ > MAX_SOFT_RETRY) ||
+ le32_to_cpu(slot_ctx->tt_info) & TT_SLOT)
+ break;
+ *status = 0;
+ xhci_cleanup_halted_endpoint(xhci, slot_id, ep_index,
+ ep_ring->stream_id, td, EP_SOFT_RESET);
+ return 0;
default:
/* do nothing */
break;
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index 6230a57..b635785 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -1496,6 +1496,7 @@ static inline const char *xhci_trb_type_string(u8 type)
/* How much data is left before the 64KB boundary? */
#define TRB_BUFF_LEN_UP_TO_BOUNDARY(addr) (TRB_MAX_BUFF_SIZE - \
(addr & (TRB_MAX_BUFF_SIZE - 1)))
+#define MAX_SOFT_RETRY 3
struct xhci_segment {
union xhci_trb *trbs;
@@ -1583,6 +1584,7 @@ struct xhci_ring {
* if we own the TRB (if we are the consumer). See section 4.9.1.
*/
u32 cycle_state;
+ unsigned int err_count;
unsigned int stream_id;
unsigned int num_segs;
unsigned int num_trbs_free;
--
2.7.4
