4.4-stable review patch. If anyone has any objections, please let me know.
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From: Mathias Nyman mathias.nyman@linux.intel.com
commit 0472bf06c6fd33c1a18aaead4c8f91e5a03d8d7b upstream.
Don't allow USB3 U1 or U2 if the latency to wake up from the U-state reaches the service interval for a periodic endpoint.
This is according to xhci 1.1 specification section 4.23.5.2 extra note:
"Software shall ensure that a device is prevented from entering a U-state where its worst case exit latency approaches the ESIT."
Allowing too long exit latencies for periodic endpoint confuses xHC internal scheduling, and new devices may fail to enumerate with a "Not enough bandwidth for new device state" error from the host.
Cc: stable@vger.kernel.org Signed-off-by: Mathias Nyman mathias.nyman@linux.intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/usb/host/xhci.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+)
--- a/drivers/usb/host/xhci.c +++ b/drivers/usb/host/xhci.c @@ -4417,6 +4417,14 @@ static u16 xhci_calculate_u1_timeout(str { unsigned long long timeout_ns;
+ /* Prevent U1 if service interval is shorter than U1 exit latency */ + if (usb_endpoint_xfer_int(desc) || usb_endpoint_xfer_isoc(desc)) { + if (xhci_service_interval_to_ns(desc) <= udev->u1_params.mel) { + dev_dbg(&udev->dev, "Disable U1, ESIT shorter than exit latency\n"); + return USB3_LPM_DISABLED; + } + } + if (xhci->quirks & XHCI_INTEL_HOST) timeout_ns = xhci_calculate_intel_u1_timeout(udev, desc); else @@ -4473,6 +4481,14 @@ static u16 xhci_calculate_u2_timeout(str { unsigned long long timeout_ns;
+ /* Prevent U2 if service interval is shorter than U2 exit latency */ + if (usb_endpoint_xfer_int(desc) || usb_endpoint_xfer_isoc(desc)) { + if (xhci_service_interval_to_ns(desc) <= udev->u2_params.mel) { + dev_dbg(&udev->dev, "Disable U2, ESIT shorter than exit latency\n"); + return USB3_LPM_DISABLED; + } + } + if (xhci->quirks & XHCI_INTEL_HOST) timeout_ns = xhci_calculate_intel_u2_timeout(udev, desc); else