Messages in this thread | | | Subject | Re: [RESEND][PATCH v3 1/2] usb: dwc3: Add avoiding vbus glitch happen during xhci reset | From | Sergei Shtylyov <> | Date | Thu, 6 Jun 2019 11:16:54 +0300 |
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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. :-)
> 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@nxp.com> > Reviewed-by: Rob Herring <robh@kernel.org> [...]
MBR, Sergei
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