xhci: Prevent U1/U2 link pm states if exit latency is too long
Subsystems (3)
PATCH 2/2 xhci: Prevent U1/U2 link pm states if exit latency is too long
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 <[email protected]>
Signed-off-by Mathias Nyman <[email protected]>
--- drivers/usb/host/xhci.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+)
drivers/usb/host/xhci.c +16 -0
@@ -4514,6 +4514,14 @@ static u16 xhci_calculate_u1_timeout(struct xhci_hcd *xhci, {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
@@ -4570,6 +4578,14 @@ static u16 xhci_calculate_u2_timeout(struct xhci_hcd *xhci, {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
Signature · 1 line
2.7.4