[PATCH] ARM: errata: Update the workaround for the 742231 Cortex-A9 erratum
From: catalin.marinas@arm.com (Catalin Marinas)
Date: 2011-12-20 14:15:02
On Tue, Dec 20, 2011 at 08:37:42AM +0000, Shinya Kuribayashi wrote:
quoted hunk ↗ jump to hunk
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 <redacted> --- 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. -- Catalin