[PATCH 1/3] ARM: brcmstb: Enable ZONE_DMA for non 64-bit

[Florian Fainelli]

On Thu, 9 Mar 2017 10:51:18 -0800, Florian Fainelli <f.fainelli at gmail.com> wrote:
> From: Al Cooper <alcooperx at gmail.com>
>
> Some Host Controller hardware blocks, like the OHCI, EHCI and SDIO
> controllers, have hardware blocks that are not capable of doing 64 bit
> DMA. These host controllers fail on boards with >3GB of memory because
> the memory above 3GB is located physically >= 0x100000000 and can only
> be accessed using 64 DMA. The way Linux is currently configured for
> BRCMSTB systems, the memory given to drivers for DMA through functions
> like dma_alloc_coherent() comes from CMA memory and CMA memory is taken
> from the top of physical memory. When these drivers get a DMA buffer
> with an address >=0x100000000, they end up dropping the upper 32 bit of
> the address causing the hardware to DMA to incorrect memory, typically
> BMEM (custom memory carveout). This issue was discovered on a
> BCM97449SSV_DDR4 system with 4GB or memory.
>
> The fix is to enable CONFIG_ZONE_DMA. On ARM systems this makes sure
> that all DMA memory is located within the first 32 bits of address
> space.
>
> Signed-off-by: Al Cooper <alcooperx at gmail.com>
> Signed-off-by: Florian Fainelli <f.fainelli at gmail.com>
> ---

Applied, thanks!
--
Florian