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From: mark.rutland@arm.com (Mark Rutland)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 2/3] dtb: change binding name to match with newer firmware DT
Date: Mon, 2 Mar 2015 14:48:58 +0000	[thread overview]
Message-ID: <20150302144858.GG16779@leverpostej> (raw)
In-Reply-To: <CAKh23Fm5HpNEfs40RTf_XtQ6ris5cCheAcY1WdLND04AwsvdSQ@mail.gmail.com>

On Fri, Feb 27, 2015 at 11:52:54PM +0000, Iyappan Subramanian wrote:
> On Fri, Feb 27, 2015 at 12:33 PM, Arnd Bergmann <arnd@arndb.de> wrote:
> > On Friday 27 February 2015 12:08:29 Iyappan Subramanian wrote:
> >> diff --git a/arch/arm64/boot/dts/apm/apm-storm.dtsi b/arch/arm64/boot/dts/apm/apm-storm.dtsi
> >> index f1ad9c2..a857794 100644
> >> --- a/arch/arm64/boot/dts/apm/apm-storm.dtsi
> >> +++ b/arch/arm64/boot/dts/apm/apm-storm.dtsi
> >> @@ -622,7 +622,7 @@
> >>                 };
> >>
> >>                 sgenet0: ethernet at 1f210000 {
> >> -                       compatible = "apm,xgene-enet";
> >> +                       compatible = "apm,xgene1-sgenet";
> >>                         status = "disabled";
> >>                         reg = <0x0 0x1f210000 0x0 0xd100>,
> >>                               <0x0 0x1f200000 0x0 0Xc300>,
> >>
> >
> > This will break booting the new dtb on older kernels, right?
> 
> This will not break booting older kernels.  In fact, this will fix it,
> by having the specific binding,
> older kernel that does not have support for these interfaces, will not
> call probe.
> 
> For example, 3.17 kernel that does not have support for SGMII based 1G
> and XFI 10G interfaces
> will not probe these interfaces when booted with newer dtb.

I'm guessing that in the existing DTBs, these nodes are always disabled?

If that's the case then we don't have a problem; we'll never probe these
nodes for an existing DTB.

Mark.

WARNING: multiple messages have this Message-ID (diff)
From: Mark Rutland <mark.rutland@arm.com>
To: Iyappan Subramanian <isubramanian@apm.com>
Cc: Arnd Bergmann <arnd@arndb.de>, David Miller <davem@davemloft.net>,
	netdev <netdev@vger.kernel.org>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	"mlangsdo@redhat.com" <mlangsdo@redhat.com>,
	patches <patches@apm.com>, Keyur Chudgar <kchudgar@apm.com>
Subject: Re: [PATCH 2/3] dtb: change binding name to match with newer firmware DT
Date: Mon, 2 Mar 2015 14:48:58 +0000	[thread overview]
Message-ID: <20150302144858.GG16779@leverpostej> (raw)
In-Reply-To: <CAKh23Fm5HpNEfs40RTf_XtQ6ris5cCheAcY1WdLND04AwsvdSQ@mail.gmail.com>

On Fri, Feb 27, 2015 at 11:52:54PM +0000, Iyappan Subramanian wrote:
> On Fri, Feb 27, 2015 at 12:33 PM, Arnd Bergmann <arnd@arndb.de> wrote:
> > On Friday 27 February 2015 12:08:29 Iyappan Subramanian wrote:
> >> diff --git a/arch/arm64/boot/dts/apm/apm-storm.dtsi b/arch/arm64/boot/dts/apm/apm-storm.dtsi
> >> index f1ad9c2..a857794 100644
> >> --- a/arch/arm64/boot/dts/apm/apm-storm.dtsi
> >> +++ b/arch/arm64/boot/dts/apm/apm-storm.dtsi
> >> @@ -622,7 +622,7 @@
> >>                 };
> >>
> >>                 sgenet0: ethernet@1f210000 {
> >> -                       compatible = "apm,xgene-enet";
> >> +                       compatible = "apm,xgene1-sgenet";
> >>                         status = "disabled";
> >>                         reg = <0x0 0x1f210000 0x0 0xd100>,
> >>                               <0x0 0x1f200000 0x0 0Xc300>,
> >>
> >
> > This will break booting the new dtb on older kernels, right?
> 
> This will not break booting older kernels.  In fact, this will fix it,
> by having the specific binding,
> older kernel that does not have support for these interfaces, will not
> call probe.
> 
> For example, 3.17 kernel that does not have support for SGMII based 1G
> and XFI 10G interfaces
> will not probe these interfaces when booted with newer dtb.

I'm guessing that in the existing DTBs, these nodes are always disabled?

If that's the case then we don't have a problem; we'll never probe these
nodes for an existing DTB.

Mark.

  reply	other threads:[~2015-03-02 14:48 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-02-27 20:08 [PATCH 0/3] Fix backward compatibility of newer firmware with older kernel Iyappan Subramanian
2015-02-27 20:08 ` Iyappan Subramanian
2015-02-27 20:08 ` [PATCH 1/3] Documentation: dts: Update compatible field description for APM X-Gene Iyappan Subramanian
2015-02-27 20:08   ` Iyappan Subramanian
2015-02-27 20:15   ` Mark Rutland
2015-02-27 20:15     ` Mark Rutland
2015-02-27 23:58     ` Iyappan Subramanian
2015-02-27 23:58       ` Iyappan Subramanian
2015-03-02 14:17       ` Mark Rutland
2015-03-02 14:17         ` Mark Rutland
2015-02-27 20:08 ` [PATCH 2/3] dtb: change binding name to match with newer firmware DT Iyappan Subramanian
2015-02-27 20:08   ` Iyappan Subramanian
2015-02-27 20:33   ` Arnd Bergmann
2015-02-27 20:33     ` Arnd Bergmann
2015-02-27 23:52     ` Iyappan Subramanian
2015-02-27 23:52       ` Iyappan Subramanian
2015-03-02 14:48       ` Mark Rutland [this message]
2015-03-02 14:48         ` Mark Rutland
2015-03-03  0:59         ` Iyappan Subramanian
2015-03-03  0:59           ` Iyappan Subramanian
2015-02-27 20:08 ` [PATCH 3/3] drivers: net: xgene: fix new firmware backward compatibility with older driver Iyappan Subramanian
2015-02-27 20:08   ` Iyappan Subramanian
2015-02-27 20:49 ` [PATCH 0/3] Fix backward compatibility of newer firmware with older kernel David Miller
2015-02-27 20:49   ` David Miller
2015-02-27 23:59   ` Iyappan Subramanian
2015-02-27 23:59     ` Iyappan Subramanian

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