Patch "usb: xhci: bInterval quirk for TI TUSB73x0" has been added to the 4.9-stable tree

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

usb: xhci: bInterval quirk for TI TUSB73x0

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
usb-xhci-binterval-quirk-for-ti-tusb73x0.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

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

From: Roger Quadros <[email protected]>

commit 69307ccb9ad7ccb653e332de68effdeaaab6907d upstream.

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(+)

@@ -1494,6 +1494,17 @@ int xhci_endpoint_init(struct xhci_hcd *
 	 */
 	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 = GET_MAX_PACKET(usb_endpoint_maxp(&ep->desc));
 	max_burst = xhci_get_endpoint_max_burst(udev, ep);

@@ -199,6 +199,9 @@ static void xhci_pci_quirks(struct devic
 			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");

@@ -1659,6 +1659,7 @@ 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;

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/usb-xhci-binterval-quirk-for-ti-tusb73x0.patch