Re: [BACKPORT 4.14.y 04/18] usb: dwc3: Allow disabling of metastability workaround
From: Mathieu Poirier
Date: Wed Sep 11 2019 - 10:01:54 EST
On Tue, 10 Sep 2019 at 08:36, Greg KH <greg@xxxxxxxxx> wrote:
> On Thu, Sep 05, 2019 at 10:17:45AM -0600, Mathieu Poirier wrote:
> > From: Roger Quadros <rogerq@xxxxxx>
> > 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?
The upstream commit is:
b8c9c6fa2002 ARM: dts: dra7: Disable USB metastability workaround for USB2
Should I just send the latter or you prefer a resend with both patches?
> greg k-h