[PATCH] arm64: dma: Drop cache invalidation from arch_dma_prep_coherent()

[Russell King (Oracle)]

On Wed, Sep 07, 2022 at 04:14:41PM +0200, Christoph Hellwig wrote:
> On Wed, Sep 07, 2022 at 03:10:35PM +0100, Russell King (Oracle) wrote:
> > If we allocate memory, clean (and maybe invalidate) the cache, and then
> > zero the memory _after_ the clean, then couldn't we be creating dirty
> > cache lines. There are caches out there that are write-allocate, which
> > means that by writing zeros to memory, you drag cache lines back into
> > the cache.
> 
> When writting through an uncached mapping?

Eww. That's going to be slow.

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