[PATCH 3.14 27/59] usb: xhci: fix config fail of FS hub behind a HS hub with MTT

From: Greg Kroah-Hartman
Date: Wed Jan 27 2016 - 14:25:46 EST

3.14-stable review patch. If anyone has any objections, please let me know.


From: Chunfeng Yun <chunfeng.yun@xxxxxxxxxxxx>

commit 096b110a3dd3c868e4610937c80d2e3f3357c1a9 upstream.

if a full speed hub connects to a high speed hub which
supports MTT, the MTT field of its slot context will be set
to 1 when xHCI driver setups an xHCI virtual device in
xhci_setup_addressable_virt_dev(); once usb core fetch its
hub descriptor, and need to update the xHC's internal data
structures for the device, the HUB field of its slot context
will be set to 1 too, meanwhile MTT is also set before,
this will cause configure endpoint command fail, so in the
case, we should clear MTT to 0 for full speed hub according
to section 6.2.2

Signed-off-by: Chunfeng Yun <chunfeng.yun@xxxxxxxxxxxx>
Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

drivers/usb/host/xhci.c | 8 ++++++++
1 file changed, 8 insertions(+)

--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -4696,8 +4696,16 @@ int xhci_update_hub_device(struct usb_hc
ctrl_ctx->add_flags |= cpu_to_le32(SLOT_FLAG);
slot_ctx = xhci_get_slot_ctx(xhci, config_cmd->in_ctx);
slot_ctx->dev_info |= cpu_to_le32(DEV_HUB);
+ /*
+ * refer to section 6.2.2: MTT should be 0 for full speed hub,
+ * but it may be already set to 1 when setup an xHCI virtual
+ * device, so clear it anyway.
+ */
if (tt->multi)
slot_ctx->dev_info |= cpu_to_le32(DEV_MTT);
+ else if (hdev->speed == USB_SPEED_FULL)
+ slot_ctx->dev_info &= cpu_to_le32(~DEV_MTT);
if (xhci->hci_version > 0x95) {
xhci_dbg(xhci, "xHCI version %x needs hub "
"TT think time and number of ports\n",