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Date:   Mon, 26 Sep 2022 12:21:56 +0200
From:   Pali =?utf-8?B?Um9ow6Fy?= <pali@kernel.org>
To:     Christophe Leroy <christophe.leroy@csgroup.eu>
Cc:     Michael Ellerman <mpe@ellerman.id.au>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Scott Wood <oss@buserror.net>, Sinan Akman <sinan@writeme.com>,
        "linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 7/7] powerpc: dts: turris1x.dts: Remove "fsl,P2020RDB-PC"
 compatible string
Message-ID: <20220926102156.y6lliukcswbrnanh@pali>
References: <20220819191557.28116-1-pali@kernel.org>
 <20220819191557.28116-8-pali@kernel.org>
 <9436f041-ba6d-0297-4026-e281acc7dbad@csgroup.eu>
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On Monday 26 September 2022 10:10:19 Christophe Leroy wrote:
> Le 19/08/2022 à 21:15, Pali Rohár a écrit :
> > "fsl,P2020RDB-PC" compatible string was present in Turris 1.x DTS file just
> > because Linux kernel required it for proper detection of P2020 processor
> > during boot.
> > 
> > This was quite a hack as CZ,NIC Turris 1.x is not compatible with
> > Freescale P2020-RDB-PC board.
> > 
> > Now when kernel has generic unified support for boards with P2020
> > processors, there is no need to have this "hack" in turris1x.dts file.
> > 
> > So remove incorrect "fsl,P2020RDB-PC" compatible string from turris1x.dts.
> 
> Oh, I thought it was not possible to modify DTSes.

Boards which have hardcoded DTB binaries in bootloader or are
kernel out-of-tree, they obviously needs to be still supported by
kernel.

> If it is, can you have a common compatible to all p2020, for instance 
> "fsl,p2020', so that you can use it in patch 5 instead of 
> of_find_node_by_path("/cpus/PowerPC,P2020@0") ?

I can add fsl,p2020. But it does not solve issue for other boards.

This string fsl,p2020 is not used by any board (yet).

Also Turris 1.x boards have burned some older DTB file in Flash NOR.

So it is problematic.

> > 
> > Signed-off-by: Pali Rohár <pali@kernel.org>
> > ---
> >   arch/powerpc/boot/dts/turris1x.dts | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/arch/powerpc/boot/dts/turris1x.dts b/arch/powerpc/boot/dts/turris1x.dts
> > index 12e08271e61f..69c38ed8a3a5 100644
> > --- a/arch/powerpc/boot/dts/turris1x.dts
> > +++ b/arch/powerpc/boot/dts/turris1x.dts
> > @@ -15,7 +15,7 @@
> >   
> >   / {
> >   	model = "Turris 1.x";
> > -	compatible = "cznic,turris1x", "fsl,P2020RDB-PC"; /* fsl,P2020RDB-PC is required for booting Linux */
> > +	compatible = "cznic,turris1x";
> >   
> >   	aliases {
> >   		ethernet0 = &enet0;