usb: xhci: add XHCI_VLI_HUB_TT_QUIRK

The integrated USB2.0 hub in the VL805 chipset has a bug where it
incorrectly determines the remaining available frame time before the
host next sends a SOF packet with an incremented frame_number.

See the USB2.0 specification sections 11.3 and 11.14.2.3.

The hub's non-periodic TT handler can transmit the IN/OUT handshake
token too late, so a following 64-byte DATA0/1 packet causes the ACK
handshake to collide with the propagated SOF. This causes port babble.

Avoid ringing doorbells for vulnerable endpoints during uFrame 7 if the
TR is Idle to stop one source of babble. An IN transfer for a Running TR
may happen at any time, so there's not much we can do about that.

Ideally a hub firmware update to properly implement frame timeouts is
needed, and to avoid spinning for up to 125us when submitting TDs to
Idle rings.

Signed-off-by: Jonathan Bell <jonathan@raspberrypi.com>

xhci: constrain XHCI_VLI_HUB_TT_QUIRK to old firmware versions

VLI have a firmware update for the VL805 which resolves the incorrect
frame time calculation in the hub's TT. Limit applying the quirk to
known-bad firmwares.

Signed-off-by: Jonathan Bell <jonathan@raspberrypi.com>

drivers/usb/host/xhci-pci.c

@@ -27,6 +27,8 @@
 #define SPARSE_DISABLE_BIT	17
 #define SPARSE_CNTL_ENABLE	0xC12C
 
+#define VL805_FW_VER_0138C0	0x0138C0
+
 /* Device for a quirk */
 #define PCI_VENDOR_ID_FRESCO_LOGIC		0x1b73
 #define PCI_DEVICE_ID_FRESCO_LOGIC_PDK		0x1000
@@ -248,6 +250,16 @@ static int xhci_pci_reinit(struct xhci_hcd *xhci, struct pci_dev *pdev)
 	return 0;
 }
 
+static u32 xhci_vl805_get_fw_version(struct pci_dev *dev)
+{
+	int ret;
+	u32 ver;
+
+	ret = pci_read_config_dword(dev, 0x50, &ver);
+	/* Default to a fw version of 0 instead of ~0 */
+	return ret ? 0 : ver;
+}
+
 static void xhci_pci_quirks(struct device *dev, struct xhci_hcd *xhci)
 {
 	struct pci_dev                  *pdev = to_pci_dev(dev);
@@ -451,6 +463,8 @@ static void xhci_pci_quirks(struct device *dev, struct xhci_hcd *xhci)
 		xhci->quirks |= XHCI_EP_CTX_BROKEN_DCS;
 		xhci->quirks |= XHCI_AVOID_DQ_ON_LINK;
 		xhci->quirks |= XHCI_VLI_SS_BULK_OUT_BUG;
+		if (xhci_vl805_get_fw_version(pdev) < VL805_FW_VER_0138C0)
+			xhci->quirks |= XHCI_VLI_HUB_TT_QUIRK;
 	}
 
 	if (pdev->vendor == PCI_VENDOR_ID_ASMEDIA &&

drivers/usb/host/xhci-ring.c

@@ -3661,6 +3661,48 @@ static int xhci_align_td(struct xhci_hcd *xhci, struct urb *urb, u32 enqd_len,
 	return 1;
 }
 
+static void xhci_vl805_hub_tt_quirk(struct xhci_hcd *xhci, struct urb *urb,
+				    struct xhci_ring *ring)
+{
+	struct list_head *tmp;
+	struct usb_device *udev = urb->dev;
+	unsigned int timeout = 0;
+	unsigned int single_td = 0;
+
+	/*
+	 * Adding a TD to an Idle ring for a FS nonperiodic endpoint
+	 * that is behind the internal hub's TT will run the risk of causing a
+	 * downstream port babble if submitted late in uFrame 7.
+	 * Wait until we've moved on into at least uFrame 0
+	 * (MFINDEX references the next SOF to be transmitted).
+	 *
+	 * Rings for IN endpoints in the Running state also risk causing
+	 * babble if the returned data is large, but there's not much we can do
+	 * about it here.
+	 */
+	if (udev->route & 0xffff0 || udev->speed != USB_SPEED_FULL)
+		return;
+
+	list_for_each(tmp, &ring->td_list) {
+		single_td++;
+		if (single_td == 2) {
+			single_td = 0;
+			break;
+		}
+	}
+	if (single_td) {
+		while (timeout < 20 &&
+		       (readl(&xhci->run_regs->microframe_index) & 0x7) == 0) {
+			udelay(10);
+			timeout++;
+		}
+		if (timeout >= 20)
+			xhci_warn(xhci, "MFINDEX didn't advance - %u.%u dodged\n",
+				  readl(&xhci->run_regs->microframe_index) >> 3,
+				  readl(&xhci->run_regs->microframe_index) & 7);
+	}
+}
+
 /* This is very similar to what ehci-q.c qtd_fill() does */
 int xhci_queue_bulk_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
 		struct urb *urb, int slot_id, unsigned int ep_index)
@@ -3815,6 +3857,8 @@ int xhci_queue_bulk_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
 	}
 
 	check_trb_math(urb, enqd_len);
+	if (xhci->quirks & XHCI_VLI_HUB_TT_QUIRK)
+		xhci_vl805_hub_tt_quirk(xhci, urb, ring);
 	giveback_first_trb(xhci, slot_id, ep_index, urb->stream_id,
 			start_cycle, start_trb);
 	return 0;
@@ -3963,6 +4007,8 @@ int xhci_queue_ctrl_tx(struct xhci_hcd *xhci, gfp_t mem_flags,
 			/* Event on completion */
 			field | TRB_IOC | TRB_TYPE(TRB_STATUS) | ep_ring->cycle_state);
 
+	if (xhci->quirks & XHCI_VLI_HUB_TT_QUIRK)
+		xhci_vl805_hub_tt_quirk(xhci, urb, ep_ring);
 	giveback_first_trb(xhci, slot_id, ep_index, 0,
 			start_cycle, start_trb);
 	return 0;

drivers/usb/host/xhci.h

@@ -1649,6 +1649,7 @@ struct xhci_hcd {
 /* Downstream VLI fixes */
 #define XHCI_AVOID_DQ_ON_LINK	BIT_ULL(56)
 #define XHCI_VLI_SS_BULK_OUT_BUG	BIT_ULL(57)
+#define XHCI_VLI_HUB_TT_QUIRK	BIT_ULL(58)
 
 	unsigned int		num_active_eps;
 	unsigned int		limit_active_eps;