04.02.2020 16:59, Thierry Reding пишет: > From: Thierry Reding <treding@xxxxxxxxxx> > > This partially reverts the DMA API support that was recently merged > because it was causing performance regressions on older Tegra devices. > Unfortunately, the cache maintenance performed by dma_map_sg() and > dma_unmap_sg() causes performance to drop by a factor of 10. > > The right solution for this would be to cache mappings for buffers per > consumer device, but that's a bit involved. Instead, we simply revert to > the old behaviour of sharing IOVA mappings when we know that devices can > do so (i.e. they share the same IOMMU domain). Needs a stable tag: Cc: <stable@xxxxxxxxxxxxxxx> # v5.5 > Reported-by: Dmitry Osipenko <digetx@xxxxxxxxx> > Signed-off-by: Thierry Reding <treding@xxxxxxxxxx> > --- > drivers/gpu/drm/tegra/gem.c | 10 +++++++- > drivers/gpu/drm/tegra/plane.c | 44 ++++++++++++++++++++--------------- > drivers/gpu/host1x/job.c | 32 ++++++++++++++++++++++--- > 3 files changed, 63 insertions(+), 23 deletions(-) Otherwise LGTM, Reviewed-by: Dmitry Osipenko <digetx@xxxxxxxxx>
