Le mercredi 23 novembre 2022 à 17:33 +0100, Daniel Vetter a écrit :
On Wed, Nov 23, 2022 at 10:33:38AM +0200, Pekka Paalanen wrote:
On Tue, 22 Nov 2022 18:33:59 +0100 Christian König christian.koenig@amd.com wrote:
We should have come up with dma-heaps earlier and make it clear that exporting a DMA-buf from a device gives you something device specific which might or might not work with others.
Apart from that I agree, DMA-buf should be capable of handling this. Question left is what documentation is missing to make it clear how things are supposed to work?
Perhaps somewhat related from Daniel Stone that seems to have been forgotten: https://lore.kernel.org/dri-devel/20210905122742.86029-1-daniels@collabora.c...
It aimed mostly at userspace, but sounds to me like the coherency stuff could use a section of its own there?
Hm yeah it would be great to land that and then eventually extend. Daniel?
There is a lot of things documented in this document that have been said to be completely wrong user-space behaviour in this thread. But it seems to pre-date the DMA Heaps. The document also assume that DMA Heaps completely solves the CMA vs system memory issue. But it also underline a very important aspect, that userland is not aware which one to use. What this document suggest though seems more realist then what has been said here.
Its overall a great document, it unfortunate that it only makes it into the DRM mailing list.
Nicolas