patch "usb: xhci: bInterval quirk for TI TUSB73x0" added to usb-next

This is a note to let you know that I've just added the patch titled

usb: xhci: bInterval quirk for TI TUSB73x0

to my usb git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-next branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will also be merged in the next major kernel release during the merge window.

If you have any questions about this process, please let me know.

From: Roger Quadros <[email protected]>
Date: Fri, 7 Apr 2017 17:57:12 +0300
Subject: usb: xhci: bInterval quirk for TI TUSB73x0

As per [1] issue #4,
"The periodic EP scheduler always tries to schedule the EPs that have large intervals (interval equal to or greater than 128 microframes) into different microframes. So it maintains an internal counter and increments for each large interval EP added. When the counter is greater than 128, the scheduler rejects the new EP. So when the hub re-enumerated 128 times, it triggers this condition."

This results in Bandwidth error when devices with periodic endpoints (ISO/INT) having bInterval > 7 are plugged and unplugged several times on a TUSB73x0 XHCI host.

Workaround this issue by limiting the bInterval to 7 (i.e. interval to 6) for High-speed or faster periodic endpoints.

[1] - http://www.ti.com/lit/er/sllz076/sllz076.pdf

---
 drivers/usb/host/xhci-mem.c | 11 +++++++++++
 drivers/usb/host/xhci-pci.c |  3 +++
 drivers/usb/host/xhci.h     |  1 +
 3 files changed, 15 insertions(+)

index b88ec9ae5d4c..2954b90e0cda 100644
@@ -1503,6 +1503,17 @@ int xhci_endpoint_init(struct xhci_hcd *xhci,
 	 */
 	max_esit_payload = xhci_get_max_esit_payload(udev, ep);
 	interval = xhci_get_endpoint_interval(udev, ep);
+
+	/* Periodic endpoint bInterval limit quirk */
+	if (usb_endpoint_xfer_int(&ep->desc) ||
+	    usb_endpoint_xfer_isoc(&ep->desc)) {
+		if ((xhci->quirks & XHCI_LIMIT_ENDPOINT_INTERVAL_7) &&
+		    udev->speed >= USB_SPEED_HIGH &&
+		    interval >= 7) {
+			interval = 6;
+		}
+	}
+
 	mult = xhci_get_endpoint_mult(udev, ep);
 	max_packet = usb_endpoint_maxp(&ep->desc);
 	max_burst = xhci_get_endpoint_max_burst(udev, ep);

index fc99f51d12e1..7b86508ac8cf 100644
@@ -199,6 +199,9 @@ static void xhci_pci_quirks(struct device *dev, struct xhci_hcd *xhci)
 			pdev->device == 0x1042)
 		xhci->quirks |= XHCI_BROKEN_STREAMS;
 
+	if (pdev->vendor == PCI_VENDOR_ID_TI && pdev->device == 0x8241)
+		xhci->quirks |= XHCI_LIMIT_ENDPOINT_INTERVAL_7;
+
 	if (xhci->quirks & XHCI_RESET_ON_RESUME)
 		xhci_dbg_trace(xhci, trace_xhci_dbg_quirks,
 				"QUIRK: Resetting on resume");

index dbe8ba934737..914968c662c9 100644
@@ -1820,6 +1820,7 @@ struct xhci_hcd {
 #define XHCI_MISSING_CAS	(1 << 24)
 /* For controller with a broken Port Disable implementation */
 #define XHCI_BROKEN_PORT_PED	(1 << 25)
+#define XHCI_LIMIT_ENDPOINT_INTERVAL_7	(1 << 26)
 
 	unsigned int		num_active_eps;
 	unsigned int		limit_active_eps;

2.12.2