On Wed, Aug 19, 2020 at 02:49:01PM +0200, Tomasz Figa wrote:
With the default config it doesn't, but with CONFIG_DMA_NONCOHERENT_CACHE_SYNC enabled it makes dma_pgprot() keep the pgprot value as is, without enforcing coherence attributes.
Which isn't selected on arm64, and that is for a good reason.
AFAIK dma_cache_sync() isn't the only way to perform the cache synchronization.
Yes, it is the only documented way to do it. And if you read the whole series instead of screaming you'd see that it provides a proper way to deal with non-coherent memory which will also work with arm64. instead of screaming
By the way, as a videobuf2 reviewer, I'd appreciate being CC'd on any series related to the subsystem-facing DMA API changes, since videobuf2 is one of the biggest users of it.
The cc list is too long - I cc lists and key maintainers. As a reviewer should should watch your subsystems lists closely.