[Intel-gfx] [PATCH v2] drm/i915/mtl: do not enable render power-gating on MTL

[Andrzej Hajda]

Multiple CI tests fails with forcewake ack timeouts if render
power gating is enabled.
BSpec 52698 states it should be 0 for MTL, but apparently
this info is outdated. Anyway since the patch makes MTL pass basic
tests added FIXME tag informing this is temporary workaround.

v2: added FIXME tag

Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/4983
Signed-off-by: Andrzej Hajda <andrzej.hajda at intel.com>
Reviewed-by: Nirmoy Das <nirmoy.das at intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
Reviewed-by: Andi Shyti <andi.shyti at linux.intel.com>
---
Changes in v2:
- added FIXME tag
- Link to v1: https://lore.kernel.org/r/20230517-mtl_disable_render_pg-v1-1-6495eebbfb24@intel.com
---
 drivers/gpu/drm/i915/gt/intel_rc6.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_rc6.c b/drivers/gpu/drm/i915/gt/intel_rc6.c
index 908a3d0f2343f4..58bb1c55294c93 100644
--- a/drivers/gpu/drm/i915/gt/intel_rc6.c
+++ b/drivers/gpu/drm/i915/gt/intel_rc6.c
@@ -117,8 +117,14 @@ static void gen11_rc6_enable(struct intel_rc6 *rc6)
 			GEN6_RC_CTL_RC6_ENABLE |
 			GEN6_RC_CTL_EI_MODE(1);
 
-	/* Wa_16011777198 - Render powergating must remain disabled */
-	if (IS_DG2_GRAPHICS_STEP(gt->i915, G10, STEP_A0, STEP_C0) ||
+	/*
+	 * Wa_16011777198 and BSpec 52698 - Render powergating must be off.
+	 * FIXME BSpec is outdated, disabling powergating for MTL is just
+	 * temporary wa and should be removed after fixing real cause
+	 * of forcewake timeouts.
+	 */
+	if (IS_METEORLAKE(gt->i915) ||
+	    IS_DG2_GRAPHICS_STEP(gt->i915, G10, STEP_A0, STEP_C0) ||
 	    IS_DG2_GRAPHICS_STEP(gt->i915, G11, STEP_A0, STEP_B0))
 		pg_enable =
 			GEN9_MEDIA_PG_ENABLE |

---
base-commit: 641646b29337c97681e0edb67ad2e08aef3fb850
change-id: 20230517-mtl_disable_render_pg-b9f9f1567f9e

Best regards,
-- 
Andrzej Hajda <andrzej.hajda at intel.com>