On 18/08/16 05:20 PM, Christian König wrote: > Am 18.08.2016 um 09:52 schrieb Michel Dänzer: >> On 18/08/16 04:41 PM, Christian König wrote: >>>> Afaiu the prime importing display gpu generates its own gem buffer >>>> handle (prime_fd_to_handle) from that dmabuf, importing scather-gather >>>> tables to access the dmabuf in system ram. As far as page flipping is >>>> concerned, so far those gem buffers / radeon_bo's aren't treated any >>>> different than native ones. During pageflip setup they get pinned into >>>> VRAM, which moves (=copies) their content from the RAM dmabuf backing >>>> store into VRAM. >>> Your understanding isn't correct. Buffers imported using prime always >>> stay in GTT, they can't be moved to VRAM. >> That's the theory, but based on Mario's description it's clear that >> there is at least one bug which either actually allows a shared buffer >> to be moved to VRAM, or at least doesn't propagate the error correctly, >> so the page flip operation "succeeds". >> >> >>> It's the DDX which copies the buffer content from the imported prime >>> handle into a native on which is enabled to scan out. >> There is no such code which could explain what Mario is seeing. > > How should this work then otherwise?
[...] > On the other hand that we accidentally move a prime imported buffer to > VRAM could be possible, but this would clearly be a rather severe bug we > hopefully have noticed already. That's what seems to be happening, based on Mario's description and patches. -- Earthling Michel Dänzer | http://www.amd.com Libre software enthusiast | Mesa and X developer
