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authorMathias Nyman <mathias.nyman@linux.intel.com>2018-12-05 14:22:39 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-12-06 13:00:10 +0100
commit0472bf06c6fd33c1a18aaead4c8f91e5a03d8d7b (patch)
tree429aa5236402a508f3144670dda76beec5dd189a
parenta7d57abcc8a5bdeb53bbf8e87558e8e0a2c2a29d (diff)
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: <stable@vger.kernel.org> Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/usb/host/xhci.c16
1 files changed, 16 insertions, 0 deletions
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index c20b85e28d81..dae3be1b9c8f 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -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