From: Russell King - ARM Linux <linux@armlinux.org.uk>
To: Nisal Menuka <nisalmenuka23@gmail.com>,
Catalin Marinas <catalin.marinas@arm.com>
Cc: dianders@chromium.org, kever.yang@rock-chips.com,
vladimir.murzin@arm.com, armlinux@m.disordat.com,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] Remove ARM errata Workarounds 458693 and 460075
Date: Sun, 16 Apr 2017 09:04:46 +0100 [thread overview]
Message-ID: <20170416080446.GI17774@n2100.armlinux.org.uk> (raw)
In-Reply-To: <1492301166-10292-1-git-send-email-nisalmenuka23@gmail.com>
On Sat, Apr 15, 2017 at 07:06:06PM -0500, Nisal Menuka wrote:
> According to ARM, these errata exist only in a version of Cortex-A8
> (r2p0) which was never built. Therefore, I believe there are no platforms
> where this workaround should be enabled.
> link :http://infocenter.arm.com/help/index.jsp?topic=
> /com.arm.doc.faqs/ka15634.html
These were submitted by ARM Ltd back in 2009 - if the silicon was never
built, there would've been no reason to submit them. Maybe Catalin can
shed some light on this, being the commit author who introduced these?
> Signed-off-by: Nisal Menuka <nisalmenuka23@gmail.com>
> ---
> arch/arm/Kconfig | 27 ---------------------------
> arch/arm/mm/proc-v7.S | 14 --------------
> 2 files changed, 41 deletions(-)
>
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index 0d4e71b..d527963 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -1005,33 +1005,6 @@ config ARM_ERRATA_430973
> Note that setting specific bits in the ACTLR register may not be
> available in non-secure mode.
>
> -config ARM_ERRATA_458693
> - bool "ARM errata: Processor deadlock when a false hazard is created"
> - depends on CPU_V7
> - depends on !ARCH_MULTIPLATFORM
> - help
> - This option enables the workaround for the 458693 Cortex-A8 (r2p0)
> - erratum. For very specific sequences of memory operations, it is
> - possible for a hazard condition intended for a cache line to instead
> - be incorrectly associated with a different cache line. This false
> - hazard might then cause a processor deadlock. The workaround enables
> - the L1 caching of the NEON accesses and disables the PLD instruction
> - in the ACTLR register. Note that setting specific bits in the ACTLR
> - register may not be available in non-secure mode.
> -
> -config ARM_ERRATA_460075
> - bool "ARM errata: Data written to the L2 cache can be overwritten with stale data"
> - depends on CPU_V7
> - depends on !ARCH_MULTIPLATFORM
> - help
> - This option enables the workaround for the 460075 Cortex-A8 (r2p0)
> - erratum. Any asynchronous access to the L2 cache may encounter a
> - situation in which recent store transactions to the L2 cache are lost
> - and overwritten with stale memory contents from external memory. The
> - workaround disables the write-allocate mode for the L2 cache via the
> - ACTLR register. Note that setting specific bits in the ACTLR register
> - may not be available in non-secure mode.
> -
> config ARM_ERRATA_742230
> bool "ARM errata: DMB operation may be faulty"
> depends on CPU_V7 && SMP
> diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S
> index d00d52c..43a4a12 100644
> --- a/arch/arm/mm/proc-v7.S
> +++ b/arch/arm/mm/proc-v7.S
> @@ -306,20 +306,6 @@ __ca8_errata:
> orreq r0, r0, #(1 << 6) @ set IBE to 1
> mcreq p15, 0, r0, c1, c0, 1 @ write aux control register
> #endif
> -#ifdef CONFIG_ARM_ERRATA_458693
> - teq r6, #0x20 @ only present in r2p0
> - mrceq p15, 0, r0, c1, c0, 1 @ read aux control register
> - orreq r0, r0, #(1 << 5) @ set L1NEON to 1
> - orreq r0, r0, #(1 << 9) @ set PLDNOP to 1
> - mcreq p15, 0, r0, c1, c0, 1 @ write aux control register
> -#endif
> -#ifdef CONFIG_ARM_ERRATA_460075
> - teq r6, #0x20 @ only present in r2p0
> - mrceq p15, 1, r0, c9, c0, 2 @ read L2 cache aux ctrl register
> - tsteq r0, #1 << 22
> - orreq r0, r0, #(1 << 22) @ set the Write Allocate disable bit
> - mcreq p15, 1, r0, c9, c0, 2 @ write the L2 cache aux ctrl register
> -#endif
> b __errata_finish
>
> __ca9_errata:
> --
> 2.7.4
>
--
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
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next prev parent reply other threads:[~2017-04-16 8:05 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-16 0:06 [PATCH] Remove ARM errata Workarounds 458693 and 460075 Nisal Menuka
2017-04-16 8:04 ` Russell King - ARM Linux [this message]
2017-04-18 15:57 ` Catalin Marinas
2017-05-02 12:27 ` Robin Murphy
2017-05-02 15:21 ` Catalin Marinas
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