On 11/16/20 12:50 PM, Rob Clark wrote:
On Mon, Nov 16, 2020 at 9:33 AM Christoph Hellwig <hch@xxxxxx> wrote:
On Sat, Nov 14, 2020 at 03:07:20PM -0500, Jonathan Marek wrote:
qcom's vulkan driver has nonCoherentAtomSize=1, and it looks like
dma_sync_single_for_cpu() does deal in some way with the partial cache line
case, although I'm not sure that means we can have a nonCoherentAtomSize=1.
No, it doesn't. You need to ensure ownership is managed at
dma_get_cache_alignment() granularity.
my guess is nonCoherentAtomSize=1 only works in the case of cache
coherent buffers
nonCoherentAtomSize doesn't apply to coherent memory (as the name
implies), I guess qcom's driver is just wrong about having
nonCoherentAtomSize=1.
Jordan just mentioned there is at least one conformance test for this, I
wonder if it just doesn't test it well enough, or just doesn't test the
non-coherent memory type?
