On 10/29/21 14:21, Matthew Auld wrote:

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 matthew.auld@intel.com Cc: Thomas Hellström thomas.hellstrom@linux.intel.com Cc: Daniel Vetter daniel@ffwll.ch

Reviewed-by: Thomas Hellström thomas.hellstrom@linux.intel.com

---

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);