[U-Boot] [PATCH v4 03/10] Exynos542x: Add workaround for ARM errata 798870

[Nishanth Menon]

On 13:27-20150220, Akshay Saraswat wrote:
> This patch adds workaround for ARM errata 798870 which says
> "If back-to-back speculative cache line fills (fill A and fill B) are
> issued from the L1 data cache of a CPU to the L2 cache, the second
> request (fill B) is then cancelled, and the second request would have
> detected a hazard against a recent write or eviction (write B) to the
> same cache line as fill B then the L2 logic might deadlock."
> 
> Signed-off-by: Kimoon Kim <kimoon.kim at samsung.com>
> Signed-off-by: Akshay Saraswat <akshay.s at samsung.com>
> Reviewed-by: Simon Glass <sjg at chromium.org>
> Tested-by: Simon Glass <sjg at chromium.org>
> ---
> Changes since v3:
> 	- Added errata number in comment.
> 	- Moved changes to arm generic armv7.h
> 
> Changes since v2:
> 	- No change.
> 
> Changes since v1:
> 	- Added Reviewed-by & Tested-by.
> 	- Added space before */ on line # 40.
> 
>  arch/arm/include/asm/armv7.h | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> diff --git a/arch/arm/include/asm/armv7.h b/arch/arm/include/asm/armv7.h
> index a13da23..a2040b7 100644
> --- a/arch/arm/include/asm/armv7.h
> +++ b/arch/arm/include/asm/armv7.h
> @@ -69,6 +69,22 @@
>  #define CP15DSB	asm volatile ("mcr     p15, 0, %0, c7, c10, 4" : : "r" (0))
>  #define CP15DMB	asm volatile ("mcr     p15, 0, %0, c7, c10, 5" : : "r" (0))
>  
> +/*
> + * Workaround for ARM errata # 798870
> + * Set L2ACTLR[7] to reissue any memory transaction in the L2 that has been
> + * stalled for 1024 cycles to verify that its hazard condition still exists.
> + */
> +static inline void v7_enable_l2_hazard_detect(void)
> +{
> +	uint32_t val;
> +
> +	/* L2ACTLR[7]: Enable hazard detect timeout */
> +	asm volatile ("mrc     p15, 1, %0, c15, c0, 0\n\t" : "=r"(val));
> +	val |= (1 << 7);
> +	asm volatile ("mcr     p15, 1, %0, c15, c0, 0\n\t" : : "r"(val));

This wont work for us in DRA7/OMAP5 L2ACTLR cannot be modified by
u-boot. has to go to secure world using smc call.

> +}
> +
> +void v7_en_l2_hazard_detect(void);
>  void v7_outer_cache_enable(void);
>  void v7_outer_cache_disable(void);
>  void v7_outer_cache_flush_all(void);

How about this - using the series:
https://patchwork.ozlabs.org/patch/443261/                
https://patchwork.ozlabs.org/patch/443264/                
https://patchwork.ozlabs.org/patch/443268/                
https://patchwork.ozlabs.org/patch/443265/                
https://patchwork.ozlabs.org/patch/443263/                
https://patchwork.ozlabs.org/patch/443262/                
https://patchwork.ozlabs.org/patch/443267/                
https://patchwork.ozlabs.org/patch/443266/                
https://patchwork.ozlabs.org/patch/443260/                
-- 
Regards,
Nishanth Menon