Re: [PATCH] usb: dwc3: core: configure PHY before initializing host in dwc3_set_mode

[Ferry Toth]

Hi,

Op 12-11-2022 om 23:46 schreef Sven Peter:
> Hi Ferry,
>
> On Sat, Nov 12, 2022, at 23:15, Ferry Toth wrote:
> > Hi Sven,
> >
> > Op 12-11-2022 om 11:25 schreef Sven Peter:
> > > Usually, first the PHY is set to the correct mode and then the host or
> > > device side of the controller is initialized afterwards. Otherwise a PHY
> > > that's already used has to be reconfigured.
> > > dwc3_core_init_mode() does this correctly for both host and device and
> > > __dwc3_set_mode() does it correctly when switching to device mode.
> > > When setting up host mode however it first initializes xhci and only
> > > then changes the PHY's mode. Let's also do the operations in the correct
> > > order here.
> > >
> > > Fixes: 958d1a4c40dd ("usb: dwc3: core: program PHY for proper DRD modes")
> > > Signed-off-by: Sven Peter <sven@xxxxxxxxxxxxx>
> > > ---
> > >    drivers/usb/dwc3/core.c | 9 +++++----
> > >    1 file changed, 5 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> > > index ad4d644e21a4..759d23d908fa 100644
> > > --- a/drivers/usb/dwc3/core.c
> > > +++ b/drivers/usb/dwc3/core.c
> > > @@ -212,14 +212,15 @@ static void __dwc3_set_mode(struct work_struct *work)
> > >    
> > >    	switch (dwc->desired_dr_role) {
> > >    	case DWC3_GCTL_PRTCAP_HOST:
> > > +		if (dwc->usb2_phy)
> > > +			otg_set_vbus(dwc->usb2_phy->otg, true);
> > > +		phy_set_mode(dwc->usb2_generic_phy, PHY_MODE_USB_HOST);
> > > +		phy_set_mode(dwc->usb3_generic_phy, PHY_MODE_USB_HOST);
> > > +
> > >    		ret = dwc3_host_init(dwc);
> > >    		if (ret) {
> > >    			dev_err(dwc->dev, "failed to initialize host\n");
> > >    		} else {
> > > -			if (dwc->usb2_phy)
> > > -				otg_set_vbus(dwc->usb2_phy->otg, true);
> > > -			phy_set_mode(dwc->usb2_generic_phy, PHY_MODE_USB_HOST);
> > > -			phy_set_mode(dwc->usb3_generic_phy, PHY_MODE_USB_HOST);
> > >    			if (dwc->dis_split_quirk) {
> > >    				reg = dwc3_readl(dwc->regs, DWC3_GUCTL3);
> > >    				reg |= DWC3_GUCTL3_SPLITDISABLE;
> > This patch breaks usb host mode on Intel Merrifield platform. I am
> > testing this on top of v6.0 +
> > * my 2 "usb: dwc3: core: defer probe on ulpi_read_id timeout" patches
> > (otherwise tusb1210 will not be probed on this platform)
> > * Revert "usb: dwc3: disable USB core PHY management" (with/without this
> > patch makes no difference)
> > * usb: dwc3: Do not get extcon device when usb-role-switch is used
> > (with/without this patch makes no difference)
> >
> > ftrace shows tusb1210 is indeed still probed, nevertheless in host mode
> > it seems vbus is not powered as my connected smsc95xx based hub is not
> > active (seems not plugged).
> >
> > Flipping the switch to device mode gadgets work fine.
> >
> > Could it be dwc3_host_init() needs to be called prior to otg_set_vbus()?
>
> Huh, thanks for testing!
>
> For the platform I'm working on I need to set the phy mode before dwc3_host_init()
> and then found the same code further below in dwc3_core_init_mode,
>
> static int dwc3_core_init_mode(struct dwc3 *dwc)
> {
> [...]
> 	case USB_DR_MODE_HOST:
> 		dwc3_set_prtcap(dwc, DWC3_GCTL_PRTCAP_HOST);
>
> 		if (dwc->usb2_phy)
> 			otg_set_vbus(dwc->usb2_phy->otg, true);
> 		phy_set_mode(dwc->usb2_generic_phy, PHY_MODE_USB_HOST);
> 		phy_set_mode(dwc->usb3_generic_phy, PHY_MODE_USB_HOST);
>
> 		ret = dwc3_host_init(dwc);
> 		if (ret)
> 			return dev_err_probe(dev, ret, "failed to initialize host\n");
> 		break;
> [...]
> }
>
> so I'm quite surprised it causes issue in __dwc3_set_mode now.
> If otg_set_vbus indeed needs to happen after dwc3_host_init it should probably
> also be called afterwards in dwc3_core_init_mode as well.

Maybe there is a difference between the case USB_DR_MODE_HOST above and 
case USB_DR_MODE_OTG touched by this patch?
> Best,
>
>
> Sven