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From: Russell King - ARM Linux <linux@armlinux.org.uk>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Chris Packham <chris.packham@alliedtelesis.co.nz>,
	Borislav Petkov <bp@alien8.de>,
	jlu@pengutronix.de, Gregory CLEMENT <gregory.clement@bootlin.com>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	DTML <devicetree@vger.kernel.org>,
	linux-edac@vger.kernel.org,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>
Subject: Re: [PATCH v6 5/9] dt-bindings: ARM: document marvell,ecc-enable binding
Date: Fri, 9 Nov 2018 11:48:19 +0000	[thread overview]
Message-ID: <20181109114818.GB30658@n2100.armlinux.org.uk> (raw)
In-Reply-To: <CAK8P3a3PNvBhyQw0bfGxKmxj+KeJB2_TXtDx2R1BpjTCYNqVkA@mail.gmail.com>

On Fri, Nov 09, 2018 at 12:40:06PM +0100, Arnd Bergmann wrote:
> On Fri, Nov 9, 2018 at 8:04 AM Chris Packham
> <chris.packham@alliedtelesis.co.nz> wrote:
> >
> > Add documentation for the marvell,ecc-enable and marvell,ecc-disable
> > properties which can be used to enable/disable ECC on the Marvell aurora
> > cache.
> >
> > Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
> > ---
> 
> Why do you need both enable and disable? Wouldn't one of them be enough here?

It isn't an "on when ecc-enable is present, off when not" because the
current behaviour is to preserve these bits in the control register.

If we were to implement it as "if no ecc-enable property, turn off
ECC" then that would drastically change the behaviour - systems which
were configured for ECC suddenly lose ECC support.

Since we don't know which have it and which don't, we can't implement
the option like that.

-- 
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up
According to speedtest.net: 11.9Mbps down 500kbps up

WARNING: multiple messages have this Message-ID (diff)
From: Russell King - ARM Linux <linux@armlinux.org.uk>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Chris Packham <chris.packham@alliedtelesis.co.nz>,
	Borislav Petkov <bp@alien8.de>,
	jlu@pengutronix.de, Gregory CLEMENT <gregory.clement@bootlin.com>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	DTML <devicetree@vger.kernel.org>,
	linux-edac@vger.kernel.org,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>
Subject: [v6,5/9] dt-bindings: ARM: document marvell,ecc-enable binding
Date: Fri, 9 Nov 2018 11:48:19 +0000	[thread overview]
Message-ID: <20181109114818.GB30658@n2100.armlinux.org.uk> (raw)

On Fri, Nov 09, 2018 at 12:40:06PM +0100, Arnd Bergmann wrote:
> On Fri, Nov 9, 2018 at 8:04 AM Chris Packham
> <chris.packham@alliedtelesis.co.nz> wrote:
> >
> > Add documentation for the marvell,ecc-enable and marvell,ecc-disable
> > properties which can be used to enable/disable ECC on the Marvell aurora
> > cache.
> >
> > Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
> > ---
> 
> Why do you need both enable and disable? Wouldn't one of them be enough here?

It isn't an "on when ecc-enable is present, off when not" because the
current behaviour is to preserve these bits in the control register.

If we were to implement it as "if no ecc-enable property, turn off
ECC" then that would drastically change the behaviour - systems which
were configured for ECC suddenly lose ECC support.

Since we don't know which have it and which don't, we can't implement
the option like that.

WARNING: multiple messages have this Message-ID (diff)
From: linux@armlinux.org.uk (Russell King - ARM Linux)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v6 5/9] dt-bindings: ARM: document marvell,ecc-enable binding
Date: Fri, 9 Nov 2018 11:48:19 +0000	[thread overview]
Message-ID: <20181109114818.GB30658@n2100.armlinux.org.uk> (raw)
In-Reply-To: <CAK8P3a3PNvBhyQw0bfGxKmxj+KeJB2_TXtDx2R1BpjTCYNqVkA@mail.gmail.com>

On Fri, Nov 09, 2018 at 12:40:06PM +0100, Arnd Bergmann wrote:
> On Fri, Nov 9, 2018 at 8:04 AM Chris Packham
> <chris.packham@alliedtelesis.co.nz> wrote:
> >
> > Add documentation for the marvell,ecc-enable and marvell,ecc-disable
> > properties which can be used to enable/disable ECC on the Marvell aurora
> > cache.
> >
> > Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
> > ---
> 
> Why do you need both enable and disable? Wouldn't one of them be enough here?

It isn't an "on when ecc-enable is present, off when not" because the
current behaviour is to preserve these bits in the control register.

If we were to implement it as "if no ecc-enable property, turn off
ECC" then that would drastically change the behaviour - systems which
were configured for ECC suddenly lose ECC support.

Since we don't know which have it and which don't, we can't implement
the option like that.

-- 
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up
According to speedtest.net: 11.9Mbps down 500kbps up

  reply	other threads:[~2018-11-09 11:48 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-09  7:03 [PATCH v6 0/9] EDAC drivers for Armada XP L2 and DDR Chris Packham
2018-11-09  7:03 ` Chris Packham
2018-11-09  7:03 ` [PATCH v6 1/9] ARM: l2c: move cache-aurora-l2.h to asm/hardware Chris Packham
2018-11-09  7:03   ` Chris Packham
2018-11-09  7:03   ` [v6,1/9] " Chris Packham
2018-11-09  7:03 ` [PATCH v6 2/9] ARM: aurora-l2: add prefix to MAX_RANGE_SIZE Chris Packham
2018-11-09  7:03   ` Chris Packham
2018-11-09  7:03   ` [v6,2/9] " Chris Packham
2018-11-09  7:03 ` [PATCH v6 3/9] ARM: aurora-l2: add defines for parity and ECC registers Chris Packham
2018-11-09  7:03   ` Chris Packham
2018-11-09  7:03   ` [v6,3/9] " Chris Packham
2018-11-09  7:03 ` [PATCH v6 4/9] ARM: l2x0: support parity-enable/disable on aurora Chris Packham
2018-11-09  7:03   ` Chris Packham
2018-11-09  7:03   ` [v6,4/9] " Chris Packham
2018-11-09  7:03 ` [PATCH v6 5/9] dt-bindings: ARM: document marvell,ecc-enable binding Chris Packham
2018-11-09  7:03   ` Chris Packham
2018-11-09  7:03   ` [v6,5/9] " Chris Packham
2018-11-09 11:40   ` [PATCH v6 5/9] " Arnd Bergmann
2018-11-09 11:40     ` [PATCH v6 5/9] dt-bindings: ARM: document marvell, ecc-enable binding Arnd Bergmann
2018-11-09 11:40     ` [v6,5/9] dt-bindings: ARM: document marvell,ecc-enable binding Arnd Bergmann
2018-11-09 11:48     ` Russell King - ARM Linux [this message]
2018-11-09 11:48       ` [PATCH v6 5/9] " Russell King - ARM Linux
2018-11-09 11:48       ` [v6,5/9] " Russell King - ARM Linux
2018-11-09 15:58       ` [PATCH v6 5/9] " Arnd Bergmann
2018-11-09 15:58         ` [PATCH v6 5/9] dt-bindings: ARM: document marvell, ecc-enable binding Arnd Bergmann
2018-11-09 15:58         ` [v6,5/9] dt-bindings: ARM: document marvell,ecc-enable binding Arnd Bergmann
2018-11-11 19:57         ` [PATCH v6 5/9] " Chris Packham
2018-11-11 19:57           ` Chris Packham
2018-11-11 19:57           ` [v6,5/9] " Chris Packham
2018-11-11 22:35   ` [PATCH v6 5/9] " Rob Herring
2018-11-11 22:35     ` Rob Herring
2018-11-11 22:35     ` Rob Herring
2018-11-11 22:35     ` [v6,5/9] " Rob Herring
2018-11-09  7:03 ` [PATCH v6 6/9] ARM: l2x0: add marvell,ecc-enable property for aurora Chris Packham
2018-11-09  7:03   ` Chris Packham
2018-11-09  7:03   ` [v6,6/9] " Chris Packham
2018-11-09  7:03 ` [PATCH v6 7/9] EDAC: Add missing debugfs_create_x32 wrapper Chris Packham
2018-11-09  7:03   ` Chris Packham
2018-11-09  7:03   ` [v6,7/9] " Chris Packham
2018-11-09  7:03 ` [PATCH v6 8/9] EDAC: Add driver for the Marvell Armada XP SDRAM and L2 cache ECC Chris Packham
2018-11-09  7:03   ` Chris Packham
2018-11-09  7:03   ` [v6,8/9] " Chris Packham
2018-11-11 19:40   ` [PATCH v6 8/9] " Borislav Petkov
2018-11-11 19:40     ` Borislav Petkov
2018-11-11 19:40     ` [v6,8/9] " Borislav Petkov
2018-11-09  7:03 ` [PATCH v6 9/9] EDAC: armada_xp: Add support for more SoCs Chris Packham
2018-11-09  7:03   ` Chris Packham
2018-11-09  7:03   ` [v6,9/9] " Chris Packham

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