We were overzealous here; even though discrete is non-LLC, it should still be always coherent.
v2(Thomas & Daniel) - Be extra cautious and limit to DG1 - Add some more commentary Signed-off-by: Matthew Auld <[email protected]> Cc: Thomas Hellström <[email protected]> Cc: Daniel Vetter <[email protected]> --- drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c index a45d0ec2c5b6..a2b485a1be8c 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c @@ -250,8 +250,19 @@ static int i915_gem_object_get_pages_dmabuf(struct drm_i915_gem_object *obj) if (IS_ERR(pages)) return PTR_ERR(pages); - /* XXX: consider doing a vmap flush or something */ - if (!HAS_LLC(i915) || i915_gem_object_can_bypass_llc(obj)) + /* + * DG1 is special here since it still snoops transactions even with + * CACHE_NONE. This is not the case with other HAS_SNOOP platforms. We + * might need to revisit this as we add new discrete platforms. + * + * XXX: Consider doing a vmap flush or something, where possible. + * Currently we just do a heavy handed wbinvd_on_all_cpus() here since + * the underlying sg_table might not even point to struct pages, so we + * can't just call drm_clflush_sg or similar, like we do elsewhere in + * the driver. + */ + if (i915_gem_object_can_bypass_llc(obj) || + (!HAS_LLC(i915) && !IS_DG1(i915))) wbinvd_on_all_cpus(); sg_page_sizes = i915_sg_dma_sizes(pages->sgl); -- 2.26.3
