[U-Boot] [PATCH] mx6: Set shared override bit in PL310 AUX_CTRL register

Catalin Marinas
2015-03-12T09:32:34Z

On Wed, Mar 11, 2015 at 08:12:12PM +0000, Fabio Estevam wrote:
> From: Fabio Estevam <fabio.estevam@freescale.com>
>
> Having bit 22 cleared in the PL310 Auxiliary Control register (shared
> attribute override enable) has the side effect of transforming Normal
> Shared Non-cacheable reads into Cacheable no-allocate reads.
>
> Coherent DMA buffers in Linux always have a Cacheable alias via the
> kernel linear mapping and the processor can speculatively load cache
> lines into the PL310 controller. With bit 22 cleared, Non-cacheable
> reads would unexpectedly hit such cache lines leading to buffer
> corruption.
>
> This was inspired by a patch from Catalin Marinas [1] and also from recent
> discussions in the linux-arm-kernel list [2] where Russell King and Rob Herring
> suggested that bootloaders should initialize the cache.
>
> [1] http://lists.infradead.org/pipermail/linux-arm-kernel/2010-November/031810.html
> [2] https://lkml.org/lkml/2015/2/20/199
>
> Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>

Acked-by: Catalin Marinas <catalin.marinas@arm.com>