xHCI 1.0: TT_THINK_TIME set

xHCI 1.0 spec says the TT Think Time field shall be set to zero if the device
is not a High-speed hub.

Signed-off-by: Andiry Xu <andiry.xu@amd.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>

1 files changed, 6 insertions, 1 deletions

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 6864759c8d1a..3abf33223b1c 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -2699,11 +2699,16 @@ int xhci_update_hub_device(struct usb_hcd *hcd, struct usb_device *hdev,
                 /* Set TT think time - convert from ns to FS bit times.
                  * 0 = 8 FS bit times, 1 = 16 FS bit times,
                  * 2 = 24 FS bit times, 3 = 32 FS bit times.
+                 *
+                 * xHCI 1.0: this field shall be 0 if the device is not a
+                 * High-spped hub.
                  */
                 think_time = tt->think_time;
                 if (think_time != 0)
                         think_time = (think_time / 666) - 1;
-                slot_ctx->tt_info |= cpu_to_le32(TT_THINK_TIME(think_time));
+                if (xhci->hci_version < 0x100 || hdev->speed == USB_SPEED_HIGH)
+                        slot_ctx->tt_info |=
+                                cpu_to_le32(TT_THINK_TIME(think_time));
         } else {
                 xhci_dbg(xhci, "xHCI version %x doesn't need hub "
                                 "TT think time or number of ports\n",