On Fri, May 31, 2019 at 08:46:58AM -0700, Eric Anholt wrote: > Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx> writes: > > > Right now, the BO is mapped as a cached region when ->vmap() is called > > and the underlying object is not a dmabuf. > > Doing that makes cache management a bit more complicated (you'd need > > to call dma_map/unmap_sg() on the ->sgt field everytime the BO is about > > to be passed to the GPU/CPU), so let's map the BO with writecombine > > attributes instead (as done in most drivers). > > > > Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx> > > --- > > Found this issue while working on panfrost perfcnt where the GPU dumps > > perf counter values in memory and the CPU reads them back in > > kernel-space. This patch seems to solve the unpredictable behavior I > > had. > > > > I can also go for the other option (call dma_map/unmap/_sg() when > > needed) if you think that's more appropriate. > > writecombined was the intent, and this makes kernel vmap match the > userspace mmap path. Since I missed that obviously: Where do the shmem helpers set write combined mode for userspace mmap? -Daniel > > Reviewed-by: Eric Anholt <eric@xxxxxxxxxx> > _______________________________________________ > dri-devel mailing list > dri-devel@xxxxxxxxxxxxxxxxxxxxx > https://lists.freedesktop.org/mailman/listinfo/dri-devel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
