From 8a89f64e5be978aec621eea7fbab654b85f90187 Mon Sep 17 00:00:00 2001
From: hselasky <hselasky@ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f>
Date: Sun, 23 Feb 2014 13:11:33 +0000
Subject: [PATCH] MFC r261795: Issue doorbell twice before finally freeing the
 DMA descriptors. This should fix DMA descriptor caching issues seen with the
 EHCI controller found in Google Chromebook C720 during removal and insertion
 of USB devices.

git-svn-id: svn://svn.freebsd.org/base/stable/10@262360 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
---
 sys/dev/usb/controller/ehci.c | 62 ++++++++++++++++++++++++++++++-----
 1 file changed, 54 insertions(+), 8 deletions(-)

diff --git a/sys/dev/usb/controller/ehci.c b/sys/dev/usb/controller/ehci.c
index fb4eecb51..e3a989729 100644
--- a/sys/dev/usb/controller/ehci.c
+++ b/sys/dev/usb/controller/ehci.c
@@ -2260,11 +2260,27 @@ ehci_device_bulk_enter(struct usb_xfer *xfer)
 	return;
 }
 
+static void
+ehci_doorbell_async(struct ehci_softc *sc)
+{
+	uint32_t temp;
+
+	/*
+	 * XXX Performance quirk: Some Host Controllers have a too low
+	 * interrupt rate. Issue an IAAD to stimulate the Host
+	 * Controller after queueing the BULK transfer.
+	 *
+	 * XXX Force the host controller to refresh any QH caches.
+	 */
+	temp = EOREAD4(sc, EHCI_USBCMD);
+	if (!(temp & EHCI_CMD_IAAD))
+		EOWRITE4(sc, EHCI_USBCMD, temp | EHCI_CMD_IAAD);
+}
+
 static void
 ehci_device_bulk_start(struct usb_xfer *xfer)
 {
 	ehci_softc_t *sc = EHCI_BUS2SC(xfer->xroot->bus);
-	uint32_t temp;
 
 	/* setup TD's and QH */
 	ehci_setup_standard_chain(xfer, &sc->sc_async_p_last);
@@ -2279,13 +2295,7 @@ ehci_device_bulk_start(struct usb_xfer *xfer)
 	if (sc->sc_flags & EHCI_SCFLG_IAADBUG)
 		return;
 
-	/* XXX Performance quirk: Some Host Controllers have a too low
-	 * interrupt rate. Issue an IAAD to stimulate the Host
-	 * Controller after queueing the BULK transfer.
-	 */
-	temp = EOREAD4(sc, EHCI_USBCMD);
-	if (!(temp & EHCI_CMD_IAAD))
-		EOWRITE4(sc, EHCI_USBCMD, temp | EHCI_CMD_IAAD);
+	ehci_doorbell_async(sc);
 }
 
 struct usb_pipe_methods ehci_device_bulk_methods =
@@ -3902,6 +3912,41 @@ ehci_set_hw_power(struct usb_bus *bus)
 	return;
 }
 
+static void
+ehci_start_dma_delay_second(struct usb_xfer *xfer)
+{
+	struct ehci_softc *sc = EHCI_BUS2SC(xfer->xroot->bus);
+
+	DPRINTF("\n");
+
+	/* trigger doorbell */
+	ehci_doorbell_async(sc);
+
+	/* give the doorbell 4ms */
+	usbd_transfer_timeout_ms(xfer,
+	    (void (*)(void *))&usb_dma_delay_done_cb, 4);
+}
+
+/*
+ * Ring the doorbell twice before freeing any DMA descriptors. Some host
+ * controllers apparently cache the QH descriptors and need a message
+ * that the cache needs to be discarded.
+ */
+static void
+ehci_start_dma_delay(struct usb_xfer *xfer)
+{
+	struct ehci_softc *sc = EHCI_BUS2SC(xfer->xroot->bus);
+
+	DPRINTF("\n");
+
+	/* trigger doorbell */
+	ehci_doorbell_async(sc);
+
+	/* give the doorbell 4ms */
+	usbd_transfer_timeout_ms(xfer,
+	    (void (*)(void *))&ehci_start_dma_delay_second, 4);
+}
+
 struct usb_bus_methods ehci_bus_methods =
 {
 	.endpoint_init = ehci_ep_init,
@@ -3914,4 +3959,5 @@ struct usb_bus_methods ehci_bus_methods =
 	.set_hw_power_sleep = ehci_set_hw_power_sleep,
 	.roothub_exec = ehci_roothub_exec,
 	.xfer_poll = ehci_do_poll,
+	.start_dma_delay = ehci_start_dma_delay,
 };
-- 
2.45.0