[PATCH] ARM: errata: Update the workaround for the 742231 Cortex-A9 erratum
catalin.marinas at arm.com
Tue Dec 20 09:15:02 EST 2011
On Tue, Dec 20, 2011 at 08:37:42AM +0000, Shinya Kuribayashi wrote:
> Workaround for the 742231 erratum has been updated, which explains
> that bit #22 is required only for Cortex-A9 MPcore configuration with
> 1 single processor and the ACP present.
> That means, it's not needed for the SMP kernel.
> Signed-off-by: Shinya Kuribayashi <shinya.kuribayashi.px at renesas.com>
> Since #742231 is associated with SMP, it's safe to remove bit #22
> for now, but I'm concerned that 'MPcore + 1 processor + ACP' case
> still remains as untreated. Do we need to support the case?
> arch/arm/mm/proc-v7.S | 1 -
> 1 files changed, 0 insertions(+), 1 deletions(-)
> diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S
> index 2c559ac..8f8fced 100644
> --- a/arch/arm/mm/proc-v7.S
> +++ b/arch/arm/mm/proc-v7.S
> @@ -352,7 +352,6 @@ __v7_setup:
> teqne r6, #0x22 @ present in r2p2
> mrceq p15, 0, r10, c15, c0, 1 @ read diagnostic register
> orreq r10, r10, #1 << 12 @ set bit #12
> - orreq r10, r10, #1 << 22 @ set bit #22
> mcreq p15, 0, r10, c15, c0, 1 @ write diagnostic register
Most A9 configurations I'm aware of are indeed SMP. But maybe you could
add a !CONFIG_SMP around bit 22 setting, just in case there are
platforms using this together with an ACP.
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