Hi Stefano,
Errata 742230 applies to r1p0, r1p1, r1p2, r1p3, r2p0, r2p1, r2p2 revision of Cortex-A9. Errata 794072 applies to r1, 2, r3, r4 revisions. Software workaround is same for both.
Since diff products use diff revisions of core, I would suggest to have it this way. Otherwise it might lead to confusion if one has to enable 742230 (for 794072 workaround) even though the core revision does not need it.
Regards, Nitin Garg
-----Original Message----- From: Stefano Babic [mailto:sbabic@denx.de] Sent: Wednesday, April 02, 2014 10:26 AM To: Garg Nitin-B37173; trini@ti.com; Estevam Fabio-R49496; sbabic@denx.de Cc: u-boot@lists.denx.de Subject: Re: [PATCH v3 1/3] ARM: Add workaround for Cortex-A9 errata 794072
Hi Nitin,
On 02/04/2014 15:55, nitin.garg@freescale.com wrote:
From: Nitin Garg nitin.garg@freescale.com
A short loop including a DMB instruction might cause a denial of service on another processor which executes a CP15 broadcast operation. Exists on r1, r2, r3, r4 revisions.
Signed-off-by: Nitin Garg nitin.garg@freescale.com Acked-by: Dirk Behme dirk.behme@de.bosch.com
README | 1 + arch/arm/cpu/armv7/start.S | 2 +- 2 files changed, 2 insertions(+), 1 deletions(-)
diff --git a/README b/README index 7cb7c4f..a496c65 100644 --- a/README +++ b/README @@ -566,6 +566,7 @@ The following options need to be configured: CONFIG_ARM_ERRATA_742230 CONFIG_ARM_ERRATA_743622 CONFIG_ARM_ERRATA_751472
CONFIG_ARM_ERRATA_794072If set, the workarounds for these ARM errata are applied early during U-Boot startup. Note that these options force the diff --git
a/arch/arm/cpu/armv7/start.S b/arch/arm/cpu/armv7/start.S index ac1e55a..f3830c8 100644 --- a/arch/arm/cpu/armv7/start.S +++ b/arch/arm/cpu/armv7/start.S @@ -205,7 +205,7 @@ ENTRY(cpu_init_cp15) mcr p15, 0, r0, c1, c0, 0 @ write system control register #endif
-#ifdef CONFIG_ARM_ERRATA_742230 +#if (defined(CONFIG_ARM_ERRATA_742230) || +defined(CONFIG_ARM_ERRATA_794072)) mrc p15, 0, r0, c15, c0, 1 @ read diagnostic register orr r0, r0, #1 << 4 @ set bit #4 mcr p15, 0, r0, c15, c0, 1 @ write diagnostic register
Apart having an additional errata number, which is the contribute of CONFIG_ARM_ERRATA_794072 ? We are already covered with CONFIG_ARM_ERRATA_742230 and the work-around for dmb is already implemented.
Best regards, Stefano Babic
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