Commit f8f80be5 authored by Mathias Nyman's avatar Mathias Nyman Committed by Greg Kroah-Hartman
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xhci: Use soft retry to recover faster from transaction errors 



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: default avatarMathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent c94d41e9

drivers/usb/host/xhci-ring.c

+19 −0
Original line number Diff line number Diff line
@@ -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;

drivers/usb/host/xhci.h

+2 −0
Original line number Diff line number Diff line
@@ -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;

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