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From:   Christoph Hellwig <hch@lst.de>
To:     Tomasz Figa <tfiga@chromium.org>
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Subject: Re: [PATCH 05/28] media/v4l2: remove
 V4L2-FLAG-MEMORY-NON-CONSISTENT
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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.