On Fri, Apr 16, 2021 at 12:49 PM Thinh Nguyen <Thinh.Nguyen@xxxxxxxxxxxx> wrote: > > John Stultz wrote: > > On Fri, Apr 16, 2021 at 3:47 AM Felipe Balbi <balbi@xxxxxxxxxx> 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 > >>> switching from host to device. John Stult reported a lockup issue seen > >>> with HiKey960 platform without these steps[1]. Similar issue is observed > >>> with Ferry's testing platform[2]. > >>> > >>> So, apply the required steps along with some fixes to Yu Chen's and John > >>> Stultz's version. The main fixes to their versions are the missing wait > >>> for clocks synchronization before clearing GCTL.CoreSoftReset and only > >>> apply DCTL.CSftRst when switching from host to device. > >>> > >>> [1] https://urldefense.com/v3/__https://lore.kernel.org/linux-usb/20210108015115.27920-1-john.stultz@xxxxxxxxxx/__;!!A4F2R9G_pg!L4TLb25Nkq0DF2qrCPWW13PUq4idhDn5QSZhgvnVAy7wJiYFOSSouSptwo9nOzIdPD4j$ > >>> [2] https://urldefense.com/v3/__https://lore.kernel.org/linux-usb/0ba7a6ba-e6a7-9cd4-0695-64fc927e01f1@xxxxxxxxx/__;!!A4F2R9G_pg!L4TLb25Nkq0DF2qrCPWW13PUq4idhDn5QSZhgvnVAy7wJiYFOSSouSptwo9nO21VT8q7$ > >>> > >>> Cc: Andy Shevchenko <andy.shevchenko@xxxxxxxxx> > >>> Cc: Ferry Toth <fntoth@xxxxxxxxx> > >>> Cc: Wesley Cheng <wcheng@xxxxxxxxxxxxxx> > >>> Cc: <stable@xxxxxxxxxxxxxxx> > >>> Fixes: 41ce1456e1db ("usb: dwc3: core: make dwc3_set_mode() work properly") > >>> Signed-off-by: Yu Chen <chenyu56@xxxxxxxxxx> > >>> Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx> > >>> Signed-off-by: Thinh Nguyen <Thinh.Nguyen@xxxxxxxxxxxx> > >> > >> I still have concerns about the soft reset, but I won't block you guys > >> from fixing Hikey's problem :-) > >> > >> The only thing I would like to confirm is that this has been verified > >> with hundreds of swaps happening as quickly as possible. DWC3 should > >> still be functional after several hundred swaps. > >> > >> Can someone confirm this is the case? (I'm assuming this can be > >> scripted) > > > > I unfortunately don't have an easy way to automate the switching right > > off. But I'll try to hack up the mux switch driver to provide an > > interface we can script against. > > > > FYI, you can do the following: > > 1) Enable "usb-role-switch" DT property if not already done so > 2) Add userspace control: > > diff --git a/drivers/usb/dwc3/drd.c b/drivers/usb/dwc3/drd.c > index e2b68bb770d1..b203e3d87291 100644 > --- a/drivers/usb/dwc3/drd.c > +++ b/drivers/usb/dwc3/drd.c > @@ -555,6 +555,7 @@ static int dwc3_setup_role_switch(struct dwc3 *dwc) > mode = DWC3_GCTL_PRTCAP_DEVICE; > } > > + dwc3_role_switch.allow_userspace_control = true; > dwc3_role_switch.fwnode = dev_fwnode(dwc->dev); > dwc3_role_switch.set = dwc3_usb_role_switch_set; > dwc3_role_switch.get = dwc3_usb_role_switch_get; > > 3) Write a script to do the following: > > # echo host > /sys/class/usb_role/<UDC>/role > > and > > # echo device > /sys/class/usb_role/<UDC>/role Thanks so much for this. So I ran both of those commands in a while loop for awhile and didn't see any trouble. HiKey960 is interesting as well because we have a mux switch, which is sort of an intermediary roll switcher (it gets the role switch signal from the tcpci_rt1711h, tweaks some gpios and then signals the dwc3). So I also did the above tweaks to the mux-switch and had it switching between device/none and validated the onboard hub came up and down along with the dwc3 core. Everything still looks good here. thanks -john thanks -john
