Hi Andiry and Alex,
I've noticed (although I don't have time to confirm again) that the
NEC/Rensas host controller seems to return these transaction errors
whenever there is a link TRB in the middle of the control transfer TD.
Have you also noticed this? If so, we should probably let Rensas know,
as it might indicate a hardware bug. Or it could mean we're doing
something odd in the xHCI driver.
Sarah Sharp
On Thu, May 05, 2011 at 06:14:07PM +0800, Andiry Xu wrote:
> 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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