[BACKPORT 4.14.y 04/18] usb: dwc3: Allow disabling of metastability workaround
greg at kroah.com
Tue Sep 10 14:36:01 UTC 2019
On Thu, Sep 05, 2019 at 10:17:45AM -0600, Mathieu Poirier wrote:
> From: Roger Quadros <rogerq at ti.com>
> commit 42bf02ec6e420e541af9a47437d0bdf961ca2972 upstream
> Some platforms (e.g. TI's DRA7 USB2 instance) have more trouble
> with the metastability workaround as it supports only
> a High-Speed PHY and the PHY can enter into an Erratic state 
> when the controller is set in SuperSpeed mode as part of
> the metastability workaround.
> This causes upto 2 seconds delay in enumeration on DRA7's USB2
> instance in gadget mode.
> If these platforms can be better off without the workaround,
> provide a device tree property to suggest that so the workaround
> is avoided.
>  Device mode enumeration trace showing PHY Erratic Error.
> irq/90-dwc3-969  d... 52.323145: dwc3_event: event (00000901): Erratic Error [U0]
> irq/90-dwc3-969  d... 52.560646: dwc3_event: event (00000901): Erratic Error [U0]
> irq/90-dwc3-969  d... 52.798144: dwc3_event: event (00000901): Erratic Error [U0]
Does the DT also need to get updated with this new id for this? Is that
a separate patch somewhere?
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