Re: [RFC PATCH] dma: coherent: respect to device 'dma-coherent' property

[Christoph Hellwig]

On Fri, Apr 14, 2023 at 04:03:07PM +0800, Zhiqiang Hou wrote:
> From: Hou Zhiqiang <Zhiqiang.Hou@xxxxxxx>
> 
> Currently, the coherent DMA memory is always mapped as writecombine
> and uncached, ignored the 'dma-coherent' property in device node,
> this patch is to map the memory as writeback and cached when the
> device has 'dma-coherent' property.

What is the use case here?  The somewhat misnamed per-device coherent
memory is intended for small per-device pools of sram or such
used for staging memory.