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. In the case, we should clear MTT to 0 for full speed hub according to section 6.2.2.
This keeps in sync with Linux kernel commit: 096b110: usb: xhci: fix config fail of FS hub behind a HS hub with MTT
Signed-off-by: Bin Meng bmeng.cn@gmail.com ---
drivers/usb/host/xhci.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c index 8c1126e..f9c6bbb 100644 --- a/drivers/usb/host/xhci.c +++ b/drivers/usb/host/xhci.c @@ -1435,8 +1435,15 @@ static int xhci_update_hub_device(struct udevice *dev, struct usb_device *udev)
/* Update hub related fields */ slot_ctx->dev_info |= cpu_to_le32(DEV_HUB); - if (hub->tt.multi && udev->speed == USB_SPEED_HIGH) + /* + * 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 (hub->tt.multi) slot_ctx->dev_info |= cpu_to_le32(DEV_MTT); + else if (udev->speed == USB_SPEED_FULL) + slot_ctx->dev_info &= cpu_to_le32(~DEV_MTT); slot_ctx->dev_info2 |= cpu_to_le32(XHCI_MAX_PORTS(udev->maxchild)); /* * Set TT think time - convert from ns to FS bit times.