Commit 57d9898b authored by Matthew Auld's avatar Matthew Auld
Browse files

drm/i915/dmabuf: drop the flush on discrete 



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: default avatarMatthew Auld <matthew.auld@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Reviewed-by: default avatarThomas Hellström <thomas.hellstrom@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211029122137.3484203-1-matthew.auld@intel.com
parent 068b1bd0

drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c

+13 −2
Original line number Diff line number Diff line
@@ -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);