Re: [PATCH 09/21] riscv: dma-mapping: skip invalidation before bidirectional DMA

Conor Dooley
2023-03-29T20:16:35Z

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On Mon, Mar 27, 2023 at 02:13:05PM +0200, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
>
> For a DMA_BIDIRECTIONAL transfer, the caches have to be cleaned
> first to let the device see data written by the CPU, and invalidated
> after the transfer to let the CPU see data written by the device.
>
> riscv also invalidates the caches before the transfer, which does
> not appear to serve any purpose.

Rationale makes sense to me..
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>

Thanks for working on all of this Arnd!

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