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>
PL310 is the L2$ controller from ARM used in many SoCs
including the Cortex-A9 based OMAP4430
Add support for some of the key PL310 operations
- Invalidate all
- Invalidate range
- Flush(clean & invalidate) all
- Flush range
Signed-off-by: Aneesh V <aneesh@ti.com>
Fabio Estevam
Wolfgang Denk
Aneesh V