RE: [RESEND][PATCH v3 1/2] usb: dwc3: Add avoiding vbus glitch happen during xhci reset

[Ran Wang]

Hi Sergei,

On Thursday, June 06, 2019 16:17 Sergei Shtylyov wrote:
> 
> Hello!
> 
> On 06.06.2019 5:54, Ran Wang wrote:
> 
> > When DWC3 is set to host mode by programming register DWC3_GCTL, VBUS
> > (or its control signal) will turn on immediately on related Root Hub
> > ports. Then the VBUS will be de-asserted for a little while during
> > xhci reset (conducted by xhci driver) for a little while and back to normal.
> >
> > This VBUS glitch might cause some USB devices emuration fail if kernel
> 
>     Enumeration. :-)

Thanks, will correct it in next version
 
Regards,
Ran

> > boot with them connected. One SW workaround which can fix this is to
> > program all PORTSC[PP] to 0 to turn off VBUS immediately after setting
> > host mode in DWC3 driver(per signal measurement result, it will be too
> > late to do it in xhci-plat.c or xhci.c).
> >
> > Signed-off-by: Ran Wang <ran.wang_1@xxxxxxx>
> > Reviewed-by: Rob Herring <robh@xxxxxxxxxx>
> [...]
> 
> MBR, Sergei