dwc_otg: fiq_fsm: Make high-speed isochronous strided transfers work properly

Certain low-bandwidth high-speed USB devices (specialist audio devices,
compressed-frame webcams) have packet intervals > 1 microframe.

Stride these transfers in the FIQ by using the start-of-frame interrupt
to restart the channel at the right time.

Author: P33M

drivers/usb/host/dwc_otg/dwc_otg_fiq_fsm.c

@@ -615,16 +615,19 @@ static int notrace noinline fiq_fsm_do_sof(struct fiq_state *state, int num_chan
 			break;
 
 		case FIQ_HS_ISOC_SLEEPING:
-			state->channel[n].fsm = FIQ_HS_ISOC_TURBO;
-			fiq_fsm_restart_channel(state, n, 0);
+			/* Is it time to wake this channel yet? */
+			if (--state->channel[n].uframe_sleeps == 0) {
+				state->channel[n].fsm = FIQ_HS_ISOC_TURBO;
+				fiq_fsm_restart_channel(state, n, 0);
+			}
 			break;
 
 		case FIQ_PER_SSPLIT_QUEUED:
 			if ((hfnum.b.frnum & 0x7) == 5)
 				break;
 			if(!fiq_fsm_tt_in_use(state, num_channels, n)) {
 				if (!fiq_fsm_too_late(state, n)) {
-					fiq_print(FIQDBG_INT, st, "SOF GO %01d", n);
+					fiq_print(FIQDBG_INT, state, "SOF GO %01d", n);
 					fiq_fsm_restart_channel(state, n, 0);
 					state->channel[n].fsm = FIQ_PER_SSPLIT_STARTED;
 				} else {
@@ -1069,8 +1072,14 @@ static int notrace noinline fiq_fsm_do_hcintr(struct fiq_state *state, int num_c
 		if (fiq_fsm_update_hs_isoc(state, n, hcint)) {
 			/* more transactions to come */
 			handled = 1;
-			restart = 1;
 			fiq_print(FIQDBG_INT, state, "HSISO M ");
+			/* For strided transfers, put ourselves to sleep */
+			if (st->hs_isoc_info.stride > 1) {
+				st->uframe_sleeps = st->hs_isoc_info.stride - 1;
+				st->fsm = FIQ_HS_ISOC_SLEEPING;
+			} else {
+				restart = 1;
+			}
 		} else {
 			st->fsm = FIQ_HS_ISOC_DONE;
 			fiq_print(FIQDBG_INT, state, "HSISO F ");

drivers/usb/host/dwc_otg/dwc_otg_fiq_fsm.h

@@ -260,12 +260,13 @@ struct fiq_dma_blob {
  * @iso_frame:	Pointer to the array of OTG URB iso_frame_descs.
  * @nrframes:	Total length of iso_frame_desc array
  * @index:	Current index (FIQ-maintained)
- *
+ * @stride:	Interval in uframes between HS isoc transactions
  */
 struct fiq_hs_isoc_info {
 	struct dwc_otg_hcd_iso_packet_desc *iso_desc;
 	unsigned int nrframes;
 	unsigned int index;
+	unsigned int stride;
 };
 
 /**
@@ -296,6 +297,8 @@ struct fiq_channel_state {
 	/* Hardware bug workaround: sometimes channel halt interrupts are
 	 * delayed until the next SOF. Keep track of when we expected to get interrupted. */
 	unsigned int expected_uframe;
+	/* number of uframes remaining (for interval > 1 HS isoc transfers) before next transfer */
+	unsigned int uframe_sleeps;
 	/* in/out for communicating number of dma buffers used, or number of ISOC to do */
 	unsigned int nrpackets;
 	struct fiq_dma_info dma_info;

drivers/usb/host/dwc_otg/dwc_otg_hcd.c

@@ -1678,6 +1678,9 @@ int fiq_fsm_queue_isoc_transaction(dwc_otg_hcd_t *hcd, dwc_otg_qh_t *qh)
 		}
 	}
 
+	st->hs_isoc_info.stride = qh->interval;
+	st->uframe_sleeps = 0;
+
 	fiq_print(FIQDBG_INT, hcd->fiq_state, "FSMQ  %01d ", hc->hc_num);
 	fiq_print(FIQDBG_INT, hcd->fiq_state, "%08x", st->hcchar_copy.d32);
 	fiq_print(FIQDBG_INT, hcd->fiq_state, "%08x", st->hctsiz_copy.d32);
@@ -1692,9 +1695,11 @@ int fiq_fsm_queue_isoc_transaction(dwc_otg_hcd_t *hcd, dwc_otg_qh_t *qh)
 	DWC_WRITE_REG32(&hc_regs->hcintmsk, st->hcintmsk_copy.d32);
 	if (hfnum.b.frrem < PERIODIC_FRREM_BACKOFF) {
 		/* Prevent queueing near EOF1. Bad things happen if a periodic
-		 * split transaction is queued very close to EOF.
+		 * split transaction is queued very close to EOF. SOF interrupt handler
+		 * will wake this channel at the next interrupt.		 *
 		 */
 		st->fsm = FIQ_HS_ISOC_SLEEPING;
+		st->uframe_sleeps = 1;
 	} else {
 		st->fsm = FIQ_HS_ISOC_TURBO;
 		st->hcchar_copy.b.chen = 1;

drivers/usb/host/dwc_otg/dwc_otg_hcd_intr.c

@@ -2297,10 +2297,10 @@ void dwc_otg_fiq_unmangle_isoc(dwc_otg_hcd_t *hcd, dwc_otg_qh_t *qh, dwc_otg_qtd
 			dwc_urb->error_count++;
 		}
 	}
+	qh->sched_frame = dwc_frame_num_inc(qh->sched_frame, qh->interval * (nr_frames - 1));
+
 	//printk_ratelimited(KERN_INFO "%s: HS isochronous of %d/%d frames with %d errors complete\n",
 	//			__FUNCTION__, i, dwc_urb->packet_count, dwc_urb->error_count);
-	hcd->fops->complete(hcd, dwc_urb->priv, dwc_urb, 0);
-	release_channel(hcd, qh->channel, qtd, DWC_OTG_HC_XFER_URB_COMPLETE);
 }
 
 /**
@@ -2543,6 +2543,8 @@ void dwc_otg_hcd_handle_hc_fsm(dwc_otg_hcd_t *hcd, uint32_t num)
 		 * fail.
 		 */
 		dwc_otg_fiq_unmangle_isoc(hcd, qh, qtd, num);
+		hcd->fops->complete(hcd, qtd->urb->priv, qtd->urb, 0);
+		release_channel(hcd, hc, qtd, DWC_OTG_HC_XFER_URB_COMPLETE);
 		break;
 
 	case FIQ_PER_SPLIT_LS_ABORTED: