From a73d9d9cfc3cfceabd91fb0b0c13e4062b6dbcd7 Mon Sep 17 00:00:00 2001
From: Al Cooper <alcooperx@gmail.com>
Date: Wed, 24 Jun 2020 16:59:46 +0300
Subject: [PATCH] xhci: Fix enumeration issue when setting max packet size for
 FS devices.
Git-commit: a73d9d9cfc3cfceabd91fb0b0c13e4062b6dbcd7
References: git-fixes
Patch-mainline: v5.8-rc3

Unable to complete the enumeration of a USB TV Tuner device.

Per XHCI spec (4.6.5), the EP state field of the input context shall
be cleared for a set address command. In the special case of an FS
device that has "MaxPacketSize0 = 8", the Linux XHCI driver does
not do this before evaluating the context. With an XHCI controller
that checks the EP state field for parameter context error this
causes a problem in cases such as the device getting reset again
after enumeration.

When that field is cleared, the problem does not occur.

This was found and fixed by Sasi Kumar.

Cc: stable@vger.kernel.org
Signed-off-by: Al Cooper <alcooperx@gmail.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20200624135949.22611-3-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Oliver Neukum <oneukum@suse.com>
---
 drivers/usb/host/xhci.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index bee5deccc83d..03b64b73eb99 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -1430,6 +1430,7 @@ static int xhci_check_maxpacket(struct xhci_hcd *xhci, unsigned int slot_id,
 				xhci->devs[slot_id]->out_ctx, ep_index);
 
 		ep_ctx = xhci_get_ep_ctx(xhci, command->in_ctx, ep_index);
+		ep_ctx->ep_info &= cpu_to_le32(~EP_STATE_MASK);/* must clear */
 		ep_ctx->ep_info2 &= cpu_to_le32(~MAX_PACKET_MASK);
 		ep_ctx->ep_info2 |= cpu_to_le32(MAX_PACKET(max_packet_size));
 
-- 
2.16.4