openwrt/target/linux/brcm2708/patches-3.18/0046-fiq_fsm-Implement-hack-for-Split-Interrupt-transacti.patch

From 099581aeb11b7eafbca02c9e69f6e6c8de0c57ec Mon Sep 17 00:00:00 2001
From: P33M <P33M@github.com>
Date: Fri, 20 Jun 2014 17:23:20 +0100
Subject: [PATCH 046/114] fiq_fsm: Implement hack for Split Interrupt
 transactions

Hubs aren't too picky about which endpoint we send Control type split
transactions to. By treating Interrupt transfers as Control, it is
possible to use the non-periodic queue in the OTG core as well as the
non-periodic FIFOs in the hub itself. This massively reduces the
microframe exclusivity/contention that periodic split transactions
otherwise have to enforce.

It goes without saying that this is a fairly egregious USB specification
violation, but it works.

Original idea by Hans Petter Selasky @ FreeBSD.org.
---
 drivers/usb/host/dwc_otg/dwc_otg_hcd.c | 32 ++++++++++++++++++++++++++------
 1 file changed, 26 insertions(+), 6 deletions(-)

--- a/drivers/usb/host/dwc_otg/dwc_otg_hcd.c
+++ b/drivers/usb/host/dwc_otg/dwc_otg_hcd.c
@@ -1055,10 +1055,11 @@ int dwc_otg_hcd_init(dwc_otg_hcd_t * hcd
 			for (i=0; i < hcd->core_if->core_params->host_channels; i++) {
 				dwc_otg_cleanup_fiq_channel(hcd, i);
 			}
-			DWC_PRINTF("FIQ FSM acceleration enabled for :\n%s%s%s",
+			DWC_PRINTF("FIQ FSM acceleration enabled for :\n%s%s%s%s",
 				(fiq_fsm_mask & 0x1) ? "Non-periodic Split Transactions\n" : "",
 				(fiq_fsm_mask & 0x2) ? "Periodic Split Transactions\n" : "",
-				(fiq_fsm_mask & 0x4) ? "High-Speed Isochronous Endpoints\n" : "");
+				(fiq_fsm_mask & 0x4) ? "High-Speed Isochronous Endpoints\n" : "",
+				(fiq_fsm_mask & 0x8) ? "Interrupt/Control Split Transaction hack enabled\n" : "");
 		}
 	}
 
@@ -1789,6 +1790,20 @@ int fiq_fsm_queue_split_transaction(dwc_
 	st->hcintmsk_copy.b.chhltd = 1;
 	st->hcintmsk_copy.b.ahberr = 1;
 
+	/* Hack courtesy of FreeBSD: apparently forcing Interrupt Split transactions
+	 * as Control puts the transfer into the non-periodic request queue and the
+	 * non-periodic handler in the hub. Makes things lots easier.
+	 */
+	if ((fiq_fsm_mask & 0x8) && hc->ep_type == UE_INTERRUPT) {
+		st->hcchar_copy.b.multicnt = 0;
+		st->hcchar_copy.b.oddfrm = 0;
+		st->hcchar_copy.b.eptype = UE_CONTROL;
+		if (hc->align_buff) {
+			st->hcdma_copy.d32 = hc->align_buff;
+		} else {
+			st->hcdma_copy.d32 = ((unsigned long) hc->xfer_buff & 0xFFFFFFFF);
+		}
+	}
 	DWC_WRITE_REG32(&hc_regs->hcdma, st->hcdma_copy.d32);
 	DWC_WRITE_REG32(&hc_regs->hctsiz, st->hctsiz_copy.d32);
 	DWC_WRITE_REG32(&hc_regs->hcsplt, st->hcsplt_copy.d32);
@@ -1842,6 +1857,9 @@ int fiq_fsm_queue_split_transaction(dwc_
 			}
 		}
 	}
+	if ((fiq_fsm_mask & 0x8) && hc->ep_type == UE_INTERRUPT)
+		start_immediate = 1;
+
 	fiq_print(FIQDBG_INT, hcd->fiq_state, "FSMQ %01d %01d", hc->hc_num, start_immediate);
 	fiq_print(FIQDBG_INT, hcd->fiq_state, "%08d", hfnum.b.frrem);
 	//fiq_print(FIQDBG_INT, hcd->fiq_state, "H:%02dP:%02d", hub_addr, port_addr);
@@ -1873,11 +1891,13 @@ int fiq_fsm_queue_split_transaction(dwc_
 			}
 			break;
 		case UE_INTERRUPT:
-				if (start_immediate) {
+			if (fiq_fsm_mask & 0x8) {
+				st->fsm = FIQ_NP_SSPLIT_STARTED;
+			} else if (start_immediate) {
 					st->fsm = FIQ_PER_SSPLIT_STARTED;
-				} else {
-					st->fsm = FIQ_PER_SSPLIT_QUEUED;
-				}
+			} else {
+				st->fsm = FIQ_PER_SSPLIT_QUEUED;
+			}
 		default:
 			break;
 	}