On Thu, Apr 15, 2021 at 07:10:34AM +0000, Thinh Nguyen wrote: > Felipe Balbi wrote: > > > > Hi, > > > > 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? > > > > > IMHO, that's a better compromise than doing a full soft reset. > > > >> @@ -40,6 +41,8 @@ > >> > >> #define DWC3_DEFAULT_AUTOSUSPEND_DELAY 5000 /* ms */ > >> > >> +static DEFINE_MUTEX(mode_switch_lock); > > > > there are several platforms which more than one DWC3 instance. Sure this > > won't break on such systems? > > > > How? Am I missing something? Please let me know so I can make the change. All data needs to be per-device, not "global for the codebase" like the way you declared this lock. thanks, greg k-h
