On Fri, Feb 16, 2024 at 12:31:05AM +0530, Radhey Shyam Pandey wrote: > From: Piyush Mehta <piyush.mehta@xxxxxxx> > > SNPS controller when configured in HOST mode maintains Inter Packet > Delay (IPD) of ~380ns which works with most of the super-speed hubs > except VIA-LAB hubs. When IPD is ~380ns HOST controller fails to > enumerate FS/LS devices when connected behind VIA-LAB hubs. > > To address the above issue, add 'snps,enable_guctl1_ipd_quirk' quirk, > This quirk set the bit 9 of GUCTL1 that enables the workaround in HW to > reduce the ULPI clock latency by 1 cycle, thus reducing the IPD (~360ns). > > Signed-off-by: Piyush Mehta <piyush.mehta@xxxxxxx> > Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey@xxxxxxx> > --- > In the zynqmp public database GUCTL1 bit 9 is reserved but it is used to > enable a fix related to Inter Packet Delay in HW. The documentation team > is working to update GUCTL1 bit 9 description. Does this just affect the zynqmp? If it does, then you don't need a property - do this based on compatible. If it does affect other devices, what prevents the workaround being performed for all dwc3 controllers? Cheers, Conor. > --- > Documentation/devicetree/bindings/usb/snps,dwc3.yaml | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/Documentation/devicetree/bindings/usb/snps,dwc3.yaml b/Documentation/devicetree/bindings/usb/snps,dwc3.yaml > index 8f5d250070c7..b226457a6e50 100644 > --- a/Documentation/devicetree/bindings/usb/snps,dwc3.yaml > +++ b/Documentation/devicetree/bindings/usb/snps,dwc3.yaml > @@ -280,6 +280,13 @@ properties: > xhci reset. And the vbus will back to 5V automatically when reset done. > type: boolean > > + snps,enable_guctl1_ipd_quirk: No underscores in properties please. > + description: > + When set, HW reduce the ULPI clock latency by 1 cycle, thus reducing > + the IPD (~360ns) and making controller enumerate FS/LS devices > + connected behind via-hubs. > + type: boolean > + > snps,is-utmi-l1-suspend: > description: > True when DWC3 asserts output signal utmi_l1_suspend_n, false when > -- > 2.34.1 >
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