Commit 0d8067f2 authored by P33M's avatar P33M Committed by popcornmix
Browse files

dwc_otg: fiq_fsm: Add non-periodic TT exclusivity constraints 

Certain hub types do not discriminate between pipe direction (IN or OUT)
when considering non-periodic transfers. Therefore these hubs get confused
if multiple transfers are issued in different directions with the same
device address and endpoint number.

Constrain queuing non-periodic split transactions so they are performed
serially in such cases.

Related: https://github.com/raspberrypi/linux/issues/2024
parent 8c4dd350

drivers/usb/host/dwc_otg/dwc_otg_fiq_fsm.c

+32 −0
Original line number Diff line number Diff line
@@ -191,6 +191,32 @@ static void notrace fiq_fsm_setup_csplit(struct fiq_state *st, int n) 
	mb();

}



/**

 * fiq_fsm_restart_np_pending() - Restart a single non-periodic contended transfer

 * @st: Pointer to the channel's state

 * @num_channels: Total number of host channels

 * @orig_channel: Channel index of completed transfer

 *

 * In the case where an IN and OUT transfer are simultaneously scheduled to the

 * same device/EP, inadequate hub implementations will misbehave. Once the first

 * transfer is complete, a pending non-periodic split can then be issued.

 */

static void notrace fiq_fsm_restart_np_pending(struct fiq_state *st, int num_channels, int orig_channel)

{

	int i;

	int dev_addr = st->channel[orig_channel].hcchar_copy.b.devaddr;

	int ep_num = st->channel[orig_channel].hcchar_copy.b.epnum;

	for (i = 0; i < num_channels; i++) {

		if (st->channel[i].fsm == FIQ_NP_SSPLIT_PENDING &&

			st->channel[i].hcchar_copy.b.devaddr == dev_addr &&

			st->channel[i].hcchar_copy.b.epnum == ep_num) {

			st->channel[i].fsm = FIQ_NP_SSPLIT_STARTED;

			fiq_fsm_restart_channel(st, i, 0);

			break;

		}

	}

}



static inline int notrace fiq_get_xfer_len(struct fiq_state *st, int n)

{

	/* The xfersize register is a bit wonky. For IN transfers, it decrements by the packet size. */
@@ -870,6 +896,9 @@ static int notrace noinline fiq_fsm_do_hcintr(struct fiq_state *state, int num_c 
				st->fsm = FIQ_NP_SPLIT_HS_ABORTED;

			}

		}

		if (st->fsm != FIQ_NP_IN_CSPLIT_RETRY) {

			fiq_fsm_restart_np_pending(state, num_channels, n);

		}

		break;



	case FIQ_NP_OUT_CSPLIT_RETRY:
@@ -919,6 +948,9 @@ static int notrace noinline fiq_fsm_do_hcintr(struct fiq_state *state, int num_c 
				st->fsm = FIQ_NP_SPLIT_HS_ABORTED;

			}

		}

		if (st->fsm != FIQ_NP_OUT_CSPLIT_RETRY) {

			fiq_fsm_restart_np_pending(state, num_channels, n);

		}

		break;



	/* Periodic split states (except isoc out) */

drivers/usb/host/dwc_otg/dwc_otg_fiq_fsm.h

+2 −0
Original line number Diff line number Diff line
@@ -178,6 +178,8 @@ enum fiq_fsm_state { 
	/* Nonperiodic state groups */

	FIQ_NP_SSPLIT_STARTED = 1,

	FIQ_NP_SSPLIT_RETRY = 2,

	/* TT contention - working around hub bugs */

	FIQ_NP_SSPLIT_PENDING = 33,

	FIQ_NP_OUT_CSPLIT_RETRY = 3,

	FIQ_NP_IN_CSPLIT_RETRY = 4,

	FIQ_NP_SPLIT_DONE = 5,

drivers/usb/host/dwc_otg/dwc_otg_hcd.c

+51 −2
Original line number Diff line number Diff line
@@ -1572,6 +1572,45 @@ int fiq_fsm_setup_periodic_dma(dwc_otg_hcd_t *hcd, struct fiq_channel_state *st, 
	}

}



/**

 * fiq_fsm_np_tt_contended() - Avoid performing contended non-periodic transfers

 * @hcd: Pointer to the dwc_otg_hcd struct

 * @qh: Pointer to the endpoint's queue head

 *

 * Certain hub chips don't differentiate between IN and OUT non-periodic pipes

 * with the same endpoint number. If transfers get completed out of order

 * (disregarding the direction token) then the hub can lock up

 * or return erroneous responses.

 *

 * Returns 1 if initiating the transfer would cause contention, 0 otherwise.

 */

int fiq_fsm_np_tt_contended(dwc_otg_hcd_t *hcd, dwc_otg_qh_t *qh)

{

	int i;

	struct fiq_channel_state *st;

	int dev_addr = qh->channel->dev_addr;

	int ep_num = qh->channel->ep_num;

	for (i = 0; i < hcd->core_if->core_params->host_channels; i++) {

		if (i == qh->channel->hc_num)

			continue;

		st = &hcd->fiq_state->channel[i];

		switch (st->fsm) {

		case FIQ_NP_SSPLIT_STARTED:

		case FIQ_NP_SSPLIT_RETRY:

		case FIQ_NP_SSPLIT_PENDING:

		case FIQ_NP_OUT_CSPLIT_RETRY:

		case FIQ_NP_IN_CSPLIT_RETRY:

			if (st->hcchar_copy.b.devaddr == dev_addr &&

				st->hcchar_copy.b.epnum == ep_num)

				return 1;

			break;

		default:

			break;

		}

	}

	return 0;

}



/*

 * Pushing a periodic request into the queue near the EOF1 point

 * in a microframe causes erroneous behaviour (frmovrun) interrupt.
@@ -1894,7 +1933,12 @@ int fiq_fsm_queue_split_transaction(dwc_otg_hcd_t *hcd, dwc_otg_qh_t *qh) 
	switch (hc->ep_type) {

		case UE_CONTROL:

		case UE_BULK:

			if (fiq_fsm_np_tt_contended(hcd, qh)) {

				st->fsm = FIQ_NP_SSPLIT_PENDING;

				start_immediate = 0;

			} else {

				st->fsm = FIQ_NP_SSPLIT_STARTED;

			}

			break;

		case UE_ISOCHRONOUS:

			if (hc->ep_is_in) {
@@ -1918,7 +1962,12 @@ int fiq_fsm_queue_split_transaction(dwc_otg_hcd_t *hcd, dwc_otg_qh_t *qh) 
			break;

		case UE_INTERRUPT:

			if (fiq_fsm_mask & 0x8) {

				if (fiq_fsm_np_tt_contended(hcd, qh)) {

					st->fsm = FIQ_NP_SSPLIT_PENDING;

					start_immediate = 0;

				} else {

					st->fsm = FIQ_NP_SSPLIT_STARTED;

				}

			} else if (start_immediate) {

					st->fsm = FIQ_PER_SSPLIT_STARTED;

			} else {