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authorRan Wang <ran.wang_1@nxp.com>2017-09-27 07:03:18 (GMT)
committerXie Xiaobo <xiaobo.xie@nxp.com>2017-12-12 07:32:32 (GMT)
commit945c9c53125dc1b404c232a37889f1e7b77bcc6c (patch)
tree69c323167147e6393d9c3b3d1c36e438dcbbfbba /kernel/backtracetest.c
parent0a7b5391ea4efbebd64504ad5108e554e988c4b6 (diff)
downloadlinux-945c9c53125dc1b404c232a37889f1e7b77bcc6c.tar.xz
usb: dwc3: workaround: disable device-initiated U1/U2
Issue: When the USB controller is configured as a USB device mode, the device initiates low power when an ACK is pending for a data packet (DP). When operating in SuperSpeed mode and when the internal condition for low power (u1/u2) is satisfied, the device initiates u1/u2 even though it has just received a DPH of the DP header (DPH). This causes the link to enter and exit low power before the device sends an ACK for the DP. This behavior can cause a transaction timeout on the host for the DP. Impact: Depending on the host transaction timeout value, the host may timeout on the transaction and the host retries the transfer. If the same issue happens again, this could result in the host resetting the device and re-enumerating. Workaround: Disable USB_DCTL (InitU1Ena, InitU2Ena) bits. As a result,the device does not initiate lowpower requests; however, it can still accept low-power requests from the host/hub and enter low power. Signed-off-by: Ran Wang <ran.wang_1@nxp.com>
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