[PATCH v10] platform: generic: andes/renesas: Add SBI EXT to check for enabling IOCP errata

[Conor.Dooley@microchip.com <Conor.Dooley@microchip.com>]

On 11/04/2023 17:36, Lad Prabhakar wrote:
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> I/O Coherence Port (IOCP) provides an AXI interface for connecting
> external non-caching masters, such as DMA controllers. The accesses
> from IOCP are coherent with D-Caches and L2 Cache.
> 
> IOCP is a specification option and is disabled on the Renesas RZ/Five
> SoC (which is based on Andes AX45MP core) due to this reason IP blocks
> using DMA will fail.
> 
> As a workaround for SoCs with IOCP disabled CMO needs to be handled by
> software. Firstly OpenSBI configures the memory region as
> "Memory, Non-cacheable, Bufferable" and passes this region as a global
> shared dma pool as a DT node. With DMA_GLOBAL_POOL enabled all DMA
> allocations happen from this region and synchronization callbacks are
> implemented to synchronize when doing DMA transactions.
> 
> SBI_EXT_ANDES_IOCP_SW_WORKAROUND checks if the IOCP errata should be
> applied to handle cache management.

I don't really have a nuanced opinion here, but I was happy a few 
versions ago, so:
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>