Re: [PATCH v3] Terasic DE0-Nano-SoC: add support

From: Sascha Hauer <s.hauer@pengutronix.de>
To: Tim Sander <tim@krieglstein.org>
Cc: "barebox@lists.infradead.org" <barebox@lists.infradead.org>,
	Steffen Trumtrar <s.trumtrar@pengutronix.de>,
	Trent Piepho <tpiepho@kymetacorp.com>
Subject: Re: [PATCH v3] Terasic DE0-Nano-SoC: add support
Date: Tue, 2 Feb 2016 15:15:42 +0100	[thread overview]
Message-ID: <20160202141542.GF4118@pengutronix.de> (raw)
In-Reply-To: <2242913.yZc50JEAEz@virgo>

Hi Tim,

On Tue, Feb 02, 2016 at 02:48:49PM +0100, Tim Sander wrote:
> On Monday 01 February 2016 19:31:53 Trent Piepho wrote:
> > On Mon, 2016-02-01 at 15:07 +0100, Tim Sander wrote:
> > 
> > > v3: forgot to amend my changes in v2.
> > > 
> > > +
> > > +static int socfpga_console_init(void)
> > > +{
> > > +       if (!of_machine_is_compatible("altr,socfpga-cyclone5"))
> > > +               return 0;
> > 
> > 
> > Seems like this should be a board specific check instead of a generic
> > one, since it's programming board specific phy timing values to a board
> > specific PHY.
> I am not sure, but as outlined below i think this is also due to the 
> compatible string of the coresponding dts within the linux kernel.
> At least i first tried a more specific dts compatible string and that failed 
> to boot.

You need to match for a board specific compatible here because this
function shall be executed for this board only, not for other boards.
This means you have to add a board specific compatible to the device
tree.

> > > +#include <arm/socfpga_cyclone5_de0_nano_soc.dts>
> > > +#include "socfpga.dtsi"
> > > +
> > > +/ {
> > > +       model = "Terasic DE0-Nano-SoC (Atlas)";
> > > +       compatible = "altr,socfpga-cyclone5", "altr,socfpga";
> > 
> > 
> > Wouldn't the right thing to do here be to have a compatible entry for
> > this board type?  Like the existing "terasic,sockit" or something more
> > specific.
> Well the problem at this point is that due to the boardspecs the compatible 
> string has to be AFAIK the same as the one used in the linux kernel. 
> Unfortunatly the coresponding dts file also has no more specific compatible 
> string.

The kernel matches for "altr,socfpga". You can add as many compatibles
before that as you like, just like the "altr,socfpga-cyclone5" string
which is present already and ignored by the kernel.

Sascha

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