Re: [PATCH 1/3] Documentation: dt: dwc3: Add snps,configure-fladj property

[Felipe Balbi <balbi-l0cyMroinI0@public.gmane.org>]

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On Thu, Jul 23, 2015 at 11:07:09AM +0000, Badola Nikhil wrote:
> > -----Original Message-----
> > From: Mark Rutland [mailto:mark.rutland-5wv7dgnIgG8@public.gmane.org]
> > Sent: Thursday, July 23, 2015 4:27 PM
> > To: Badola Nikhil-B46172
> > Cc: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; balbi@ti.com
> > Subject: Re: [PATCH 1/3] Documentation: dt: dwc3: Add snps,configure-fladj
> > property
> > 
> > On Thu, Jul 23, 2015 at 11:52:19AM +0100, Badola Nikhil wrote:
> > > > -----Original Message-----
> > > > From: Mark Rutland [mailto:mark.rutland-5wv7dgnIgG8@public.gmane.org]
> > > > Sent: Thursday, July 23, 2015 3:27 PM
> > > > To: Badola Nikhil-B46172
> > > > Cc: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org;
> > > > balbi-l0cyMroinI0@public.gmane.org
> > > > Subject: Re: [PATCH 1/3] Documentation: dt: dwc3: Add
> > > > snps,configure-fladj property
> > > >
> > > > On Thu, Jul 23, 2015 at 11:09:21AM +0100, Nikhil Badola wrote:
> > > > > Add property snps,configure-fladj for enabling post silicon frame
> > > > > length adjustment
> > > > >
> > > > > Signed-off-by: Nikhil Badola <nikhil.badola-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
> > > > > ---
> > > > >  Documentation/devicetree/bindings/usb/dwc3.txt | 1 +
> > > > >  1 file changed, 1 insertion(+)
> > > > >
> > > > > diff --git a/Documentation/devicetree/bindings/usb/dwc3.txt
> > > > > b/Documentation/devicetree/bindings/usb/dwc3.txt
> > > > > index 0815eac..90c3972 100644
> > > > > --- a/Documentation/devicetree/bindings/usb/dwc3.txt
> > > > > +++ b/Documentation/devicetree/bindings/usb/dwc3.txt
> > > > > @@ -40,6 +40,7 @@ Optional properties:
> > > > >   - snps,hird-threshold: HIRD threshold
> > > > >   - snps,hsphy_interface: High-Speed PHY interface selection
> > > > > between
> > > > "utmi" for
> > > > >     UTMI+ and "ulpi" for ULPI when the DWC_USB3_HSPHY_INTERFACE
> > > > > has
> > > > value 3.
> > > > > + - snps,configure-fladj: enables post-silicon frame length
> > > > > + adjustment
> > > >
> > > > Could you elaborate on what this means and why you think it's
> > necessary?
> > >
> > > This property enables the use of GFLADJ_30MHZ field value of gfladj
> > > register for frame length adjustment instead of considering from the
> > sideband input signal fladj_30mhz_reg from SOC.
> > > This is required when signal fladj_30mhz_reg is connected to a wrong
> > > value or is not valid as in our case, hence post-silicon.
> > 
> > Ok, so this is basically an override for the GFLADJ_30MHZ field of the gfladj
> > register when there was a problem at integration time.
> >
> 
> That's right. 
>  
> > > However this field can be used to adjust any offset ranging from 00h
> > > to 3Fh, from the clock source generating SOF(start of frame) packets.
> > > Thus, this property can be added to device tree with appropriate
> > adjustment value.
> > 
> > It takes a value? The description above makes it sound like a boolean
> > property.
> > 
> > I'd expect a description more like:
> > 
> > - snps,fladj-override: Value for GFLADJ_30MHZ when the fladj_30mhz_reg
> >   signal is invalid or incorrect.
> > 
> > Which makes it clear what the value is and when it should be set.
> 
> Agreed. Will change and send a new version of the patch-set.

BTW, I'm not going to accept this without a glue layer making use of it.
Also, this patch needs to go to linux-usb as well, please resend.

-- 
balbi

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