Re: [PATCH 3/3] usb: dwc2: prevent core phy initialisation

[Quentin Schulz]

Hi Greg,

On 12/9/22 13:13, Greg Kroah-Hartman wrote:
> On Fri, Dec 09, 2022 at 12:15:34PM +0100, Quentin Schulz wrote:
> > Hi Greg,
> >
> > On 12/8/22 16:53, Greg Kroah-Hartman wrote:
> > > On Wed, Dec 07, 2022 at 02:19:18PM +0100, Quentin Schulz wrote:
> > > > From: Bin Yang <yangbin@xxxxxxxxxxxxxx>
> > > >
> > > > The usb phys need to be controlled dynamically on some Rockchip SoCs.
> > > > So set the new HCD flag which prevents USB core from trying to manage
> > > > our phys.
> > > >
> > > > Signed-off-by: Bin Yang <yangbin@xxxxxxxxxxxxxx>
> > > > Signed-off-by: Frank Wang <frank.wang@xxxxxxxxxxxxxx>
> > > > Signed-off-by: Quentin Schulz <quentin.schulz@xxxxxxxxxxxxxxxxxxxxx>
> > > > ---
> > > >    drivers/usb/dwc2/hcd.c | 7 +++++++
> > > >    1 file changed, 7 insertions(+)
> > > >
> > > > diff --git a/drivers/usb/dwc2/hcd.c b/drivers/usb/dwc2/hcd.c
> > > > index 657f1f659ffaf..757a66fa32fa8 100644
> > > > --- a/drivers/usb/dwc2/hcd.c
> > > > +++ b/drivers/usb/dwc2/hcd.c
> > > > @@ -5315,6 +5315,13 @@ int dwc2_hcd_init(struct dwc2_hsotg *hsotg)
> > > >    	if (!IS_ERR_OR_NULL(hsotg->uphy))
> > > >    		otg_set_host(hsotg->uphy->otg, &hcd->self);
> > > > +	/*
> > > > +	 * do not manage the PHY state in the HCD core, instead let the driver
> > > > +	 * handle this (for example if the PHY can only be turned on after a
> > > > +	 * specific event)
> > > > +	 */
> > > > +	hcd->skip_phy_initialization = 1;
> > >
> > > Wait, doesn't this mess with the phy logic for all other chips that use
> > > this IP block?  Have you tested this on other systems?
> >
> > I have not. I asked this in the cover-letter but I guess I should have made
> > the patch series an RFC for this reason?
>
> Ah, should I drop the first 2 in this series that I already applied?

Up to you. I need the three patches to have it (somewhat) working, so 
only merging the first two isn't going to improve the current situation 
much for me. I don't mind carrying them over for a v2 (or how many 
versions are needed).

> > > I'd like some verification first before taking this change as it seems
> > > very specific-platform.
> >
> > There's already some platform-specific callbacks for the driver (see
> > dwc2_set_rk_params in drivers/usb/dwc2/params.c) but this gets called too
> > early, before hcd structure is actually allocated. So we either need to use
> > some "proxy"/shadow variable in dwc2_core_params and then update it right
> > after hcd gets allocated or have another platform-specific callback only for
> > hcd (post-)initialization.
> >
> > Nothing too fancy so shouldn't take too long to implement. Any preference?
> > Something else?
>
> Which ever you think would be simplest.

Got it.

Cheers,
Quentin