linux-kernel - [PATCH 3.4 038/107] xhci: Calculate old endpoints correctly on device reset

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Message-Id: <1458115601-5762-38-git-send-email-lizf@kernel.org>
Date:	Wed, 16 Mar 2016 16:05:32 +0800
From:	lizf@...nel.org
To:	stable@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, Brian Campbell <bacam@...3.org.uk>,
	Mathias Nyman <mathias.nyman@...ux.intel.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Zefan Li <lizefan@...wei.com>
Subject: [PATCH 3.4 038/107] xhci: Calculate old endpoints correctly on device reset

From: Brian Campbell <bacam@...3.org.uk>

3.4.111-rc1 review patch.  If anyone has any objections, please let me know.

------------------

commit 326124a027abc9a7f43f72dc94f6f0f7a55b02b3 upstream.

When resetting a device the number of active TTs may need to be
corrected by xhci_update_tt_active_eps, but the number of old active
endpoints supplied to it was always zero, so the number of TTs and the
bandwidth reserved for them was not updated, and could rise
unnecessarily.

This affected systems using Intel's Patherpoint chipset, which rely on
software bandwidth checking.  For example, a Lenovo X230 would lose the
ability to use ports on the docking station after enough suspend/resume
cycles because the bandwidth calculated would rise with every cycle when
a suitable device is attached.

The correct number of active endpoints is calculated in the same way as
in xhci_reserve_bandwidth.

Signed-off-by: Brian Campbell <bacam@...3.org.uk>
Signed-off-by: Mathias Nyman <mathias.nyman@...ux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Zefan Li <lizefan@...wei.com>
---
 drivers/usb/host/xhci.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index d96652d..fd52e1e 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -3368,6 +3368,9 @@ int xhci_discover_or_reset_device(struct usb_hcd *hcd, struct usb_device *udev)
 			return -EINVAL;
 	}

+	if (virt_dev->tt_info)
+		old_active_eps = virt_dev->tt_info->active_eps;
+
 	if (virt_dev->udev != udev) {
 		/* If the virt_dev and the udev does not match, this virt_dev
 		 * may belong to another udev.
-- 
1.9.1