Re: [PATCH 1/2] usb: dwc3: wait for the port to leave RxDetect before xHCI reset

[sashiko-bot@kernel.org]

> From: Xu Yang <xu.yang_2@nxp.com>
> 
> When the host controller loses power during system suspend, the port
> state is not retained. After power is restored, the port starts in the
> Disconnected (RxDetect) state instead of its previous Enabled (U3)
> state.
> 
> After the controller is switched back to host mode, testing on an i.MX8/9
> SoC shows that it takes about 2 ms for the port to leave RxDetect and
> enter Polling. If xHCI is reset while the port is still in RxDetect, the
> port does not issue a Warm Reset.
> 
> This prevents the link from recovering because the USB3 device may
> still be in U3. Once the port enters Polling, it sends LFPS.Polling, but
> the device does not respond as expected. After three Polling attempts,
> each taking about 360 ms (tPollingLFPSTimeout), the controller reports
> the device as disconnected.
> 
> If xHCI is reset after the port has entered Polling, the port issues a
> Warm Reset and the link recovers quickly after the device responds.
> 
> Add a 2 ms delay through the xHCI resume quirk before resetting xHCI.
> This allows the port to leave RxDetect so that a Warm Reset can be
> issued, avoiding an unnecessary device disconnect during system
> resume.
> 
> Signed-off-by: Xu Yang <xu.yang_2@nxp.com>

Sashiko has reviewed this patch and found no issues.

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Sashiko AI review · https://sashiko.dev/#/patchset/20261106111943.2868733-1-xu.yang_2@oss.nxp.com?part=1