|author||Sarah Sharp <email@example.com>||2012-05-08 09:22:49 -0700|
|committer||Sarah Sharp <firstname.lastname@example.org>||2012-05-17 10:36:57 -0700|
xhci: Add new short TX quirk for Fresco Logic host.
Sergio reported that when he recorded audio from a USB headset mic plugged into the USB 3.0 port on his ASUS N53SV-DH72, the audio sounded "robotic". When plugged into the USB 2.0 port under EHCI on the same laptop, the audio sounded fine. The device is: Bus 002 Device 004: ID 046d:0a0c Logitech, Inc. Clear Chat Comfort USB Headset The problem was tracked down to the Fresco Logic xHCI host controller not correctly reporting short transfers on isochronous IN endpoints. The driver would submit a 96 byte transfer, the device would only send 88 or 90 bytes, and the xHCI host would report the transfer had a "successful" completion code, with an untransferred buffer length of 8 or 6 bytes. The successful completion code and non-zero untransferred length is a contradiction. The xHCI host is supposed to only mark a transfer as successful if all the bytes are transferred. Otherwise, the transfer should be marked with a short packet completion code. Without the EHCI bus trace, we wouldn't know whether the xHCI driver should trust the completion code or the untransferred length. With it, we know to trust the untransferred length. Add a new xHCI quirk for the Fresco Logic host controller. If a transfer is reported as successful, but the untransferred length is non-zero, print a warning. For the Fresco Logic host, change the completion code to COMP_SHORT_TX and process the transfer like a short transfer. This should be backported to stable kernels that contain the commit f5182b4155b9d686c5540a6822486400e34ddd98 "xhci: Disable MSI for some Fresco Logic hosts." That commit was marked for stable kernels as old as 2.6.36. Signed-off-by: Sarah Sharp <email@example.com> Reported-by: Sergio Correia <firstname.lastname@example.org> Tested-by: Sergio Correia <email@example.com> Cc: firstname.lastname@example.org Signed-off-by: Sarah Sharp <email@example.com>
Diffstat (limited to 'drivers/usb/host/xhci-pci.c')
1 files changed, 1 insertions, 0 deletions
diff --git a/drivers/usb/host/xhci-pci.c b/drivers/usb/host/xhci-pci.c
index 7a856a767e77..19e89216436e 100644
@@ -72,6 +72,7 @@ static void xhci_pci_quirks(struct device *dev, struct xhci_hcd *xhci)
xhci_dbg(xhci, "QUIRK: Fresco Logic revision %u "
"has broken MSI implementation\n",
+ xhci->quirks |= XHCI_TRUST_TX_LENGTH;
if (pdev->vendor == PCI_VENDOR_ID_NEC)