Re: [PATCH v6 3/5] usb: dwc3: add phyif_utmi_quirk

[William.wu]

Dear Rob,


On 2016/7/11 22:54, Rob Herring wrote:
> On Fri, Jul 08, 2016 at 02:33:09PM +0200, Heiko Stuebner wrote:
> > Hi William,
> >
> > Am Donnerstag, 7. Juli 2016, 10:54:24 schrieb William Wu:
> > > Add a quirk to configure the core to support the
> > > UTMI+ PHY with an 8- or 16-bit interface. UTMI+ PHY
> > > interface is hardware property, and it's platform
> > > dependent. Normall, the PHYIf can be configured
> > > during coreconsultant. But for some specific usb
> > > cores(e.g. rk3399 soc dwc3), the default PHYIf
> > > configuration value is fault, so we need to
> > > reconfigure it by software.
> > >
> > > And refer to the dwc3 databook, the GUSB2PHYCFG.USBTRDTIM
> > > must be set to the corresponding value according to
> > > the UTMI+ PHY interface.
> > >
> > > Signed-off-by: William Wu <william.wu@xxxxxxxxxxxxxx>
> > > ---
> > [...]
> > > diff --git a/Documentation/devicetree/bindings/usb/dwc3.txt
> > > b/Documentation/devicetree/bindings/usb/dwc3.txt index 020b0e9..8d7317d
> > > 100644
> > > --- a/Documentation/devicetree/bindings/usb/dwc3.txt
> > > +++ b/Documentation/devicetree/bindings/usb/dwc3.txt
> > > @@ -42,6 +42,10 @@ Optional properties:
> > >    - snps,dis-u2-freeclk-exists-quirk: when set, clear the
> > > u2_freeclk_exists in GUSB2PHYCFG, specify that USB2 PHY doesn't provide
> > >   			a free-running PHY clock.
> > > + - snps,phyif-utmi-quirk: when set core will set phyif UTMI+ interface.
> > > + - snps,phyif-utmi: the value to configure the core to support a UTMI+
> > > PHY +			with an 8- or 16-bit interface. Value 0 select 8-bit
> > > +			interface, value 1 select 16-bit interface.
> > maybe
> > 	snps,phyif-utmi-width = <8> or <16>;
> Seems like this could be common. Any other bindings have something
> similar already? If not "utmi-width" is fine.

It seems that there's not any dwc3 binding similar to this.
So I prefer to use “utmi-width”. :-)

> > devicetree is about describing the hardware, not the things that get written
> > to registers :-) . The conversion from the described width to the register
> > value can easily be done in the driver.
> >
> >
> > Also I don't think you need two properties for this. If the snps,phyif-utmi
> > property is specified it indicates that you want to manually set the width
> > and if it is absent you want to use the IC default. All functions reading
> > property-values indicate if the property is missing.
> Agreed.
>
> Rob