Re: [PATCH v3] Axi-usb: Add support for 64-bit addressing.

[Arnd Bergmann <arnd@arndb.de>]

On Wednesday, May 25, 2016 12:34:19 PM CEST Rob Herring wrote:
> On Tue, May 24, 2016 at 11:47:31AM +0000, Nava kishore Manne wrote:
> > 
> > 
> > > -----Original Message-----
> > > From: Arnd Bergmann [mailto:arnd@arndb.de]
> > > Sent: Tuesday, May 24, 2016 2:21 PM
> > > To: Nava kishore Manne <navam@xilinx.com>
> > > Cc: robh+dt@kernel.org; pawel.moll@arm.com; mark.rutland@arm.com;
> > > ijc+devicetree@hellion.org.uk; galak@codeaurora.org; Michal Simek
> > > <michals@xilinx.com>; Soren Brinkmann <sorenb@xilinx.com>;
> > > balbi@ti.com; gregkh@linuxfoundation.org; Hyun Kwon
> > > <hyunk@xilinx.com>; Nava kishore Manne <navam@xilinx.com>; Radhey
> > > Shyam Pandey <radheys@xilinx.com>; devicetree@vger.kernel.org; linux-
> > > arm-kernel@lists.infradead.org; linux-kernel@vger.kernel.org
> > > Subject: Re: [PATCH v3] Axi-usb: Add support for 64-bit addressing.
> > > 
> > > On Tuesday, May 24, 2016 10:51:08 AM CEST Nava kishore Manne wrote:
> > > > diff --git a/Documentation/devicetree/bindings/usb/udc-xilinx.txt
> > > > b/Documentation/devicetree/bindings/usb/udc-xilinx.txt
> > > > index 47b4e39..09df757 100644
> > > > --- a/Documentation/devicetree/bindings/usb/udc-xilinx.txt
> > > > +++ b/Documentation/devicetree/bindings/usb/udc-xilinx.txt
> > > > @@ -1,18 +1,23 @@
> > > >  Xilinx USB2 device controller
> > > >
> > > >  Required properties:
> > > > -- compatible             : Should be "xlnx,usb2-device-4.00.a"
> > > > +- compatible             : Should be "xlnx,usb2-device-4.00.a" or
> > > > +                   "xlnx,usb2-device-5.00"
> > > >  - reg                    : Physical base address and size of the USB2
> > > >                     device registers map.
> > > >  - interrupts             : Should contain single irq line of USB2 device
> > > >                     controller
> > > >  - xlnx,has-builtin-dma   : if DMA is included
> > > > +- dma-ranges             : Should be as the following
> > > > +                   <child-bus-address, parent-bus-address, length>
> > > 
> > > A USB host should not have any children that are DMA capable, I think, so
> > > this property doesn't make sense here. It should be part of the parent bus.
> > > 
> > Will send next version (v4) by removing this property from the DT.
> > 
> > > > +- xlnx,addrwidth : Should be the dma addressing size in bits(ex: 64
> > > bits)
> > > 
> > > I'm still unconvinced about the property definition here. What are the
> > > possible options for the IP block? I don't think I ever saw a reply from you to
> > > my earlier questions.
> > > 
> > 
> > Sorry Let me clearly explain
> > 
> > From the IP version 5.0 onwards The IP support both 32-bit and 64-bit addressing.
> > But the older version of the IP's supports only 32-bit addressing.
> > 
> > This addrwidth property differentiates the address width for the new IP (I mean 5.0 version on wards)
> > For older IP it will be always 32-bit.
> 
> Then I think you should have a simple boolean property for 64-bit 
> configuration.

I think matching on the version number is slightly better, as we have the version
already and it identifies whether the register exists.

Having a boolean property of course works as well, it just duplicates that
information.

	Arnd