Hi Felipe, Thinh Nguyen wrote: > Felipe Balbi wrote: >> >> Hi, >> >> Thinh Nguyen <Thinh.Nguyen@xxxxxxxxxxxx> writes: >>>> Thinh Nguyen <Thinh.Nguyen@xxxxxxxxxxxx> writes: >>>>> From: Yu Chen <chenyu56@xxxxxxxxxx> >>>>> From: John Stultz <john.stultz@xxxxxxxxxx> >>>>> >>>>> According to the programming guide, to switch mode for DRD controller, >>>>> the driver needs to do the following. >>>>> >>>>> To switch from device to host: >>>>> 1. Reset controller with GCTL.CoreSoftReset >>>>> 2. Set GCTL.PrtCapDir(host mode) >>>>> 3. Reset the host with USBCMD.HCRESET >>>>> 4. Then follow up with the initializing host registers sequence >>>>> >>>>> To switch from host to device: >>>>> 1. Reset controller with GCTL.CoreSoftReset >>>>> 2. Set GCTL.PrtCapDir(device mode) >>>>> 3. Reset the device with DCTL.CSftRst >>>>> 4. Then follow up with the initializing registers sequence >>>>> >>>>> Currently we're missing step 1) to do GCTL.CoreSoftReset and step 3) of >>>> >>>> we're not really missing, it was a deliberate choice :-) The only reason >>>> why we need the soft reset is because host and gadget registers map to >>>> the same physical space within dwc3 core. If we cache and restore the >>>> affected registers, we're good ;-) >>> >>> It's part of the programming model. I've already discussed with internal >>> RTL designers. This is needed, and I've provided the discussion we had >>> prior also. We have several different devices in the wild that need >>> this. What is the concern? >> >> Timing :-) If anyone wants to support OTG spec, it'll be super hard to >> guarantee the timing mandated by the spec if we have to go through full >> reset. > > This is for DRD only. It should not impact the old OTG flow. We already > have the check in place. > I thought I checked for OTG, but I missed it. I think v3 should cover it. Thanks, Thinh
