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@xxxxxxx> 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@xxxxxxxxxxxxx/ > > > > 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
