[Intel-gfx] [RFC] Revert "drm/i915/bdw: Enable execlists by default where supported"

[Paulo Zanoni]

From: Paulo Zanoni <paulo.r.zanoni at intel.com>

This reverts commit 27401d126b5b1c8dd4df98bbb60b09ff2b3d5e60.

When we run the Runtime PM test suite, all the test cases that happen
after the system-suspend test always fail on my BDW machine.

Testcase: igt/pm_rpm/system-suspend-execbuf
Testcase: igt/pm_rpm/system-suspend-modeset
Testcase: igt/pm_rpm/gem-execbuf-stress (and others ran after the
system-suspend subtest)
Cc: Thomas Daniel <thomas.daniel at intel.com>
Signed-off-by: Paulo Zanoni <paulo.r.zanoni at intel.com>
---
 drivers/gpu/drm/i915/i915_params.c | 4 ++--
 drivers/gpu/drm/i915/intel_lrc.c   | 3 ++-
 2 files changed, 4 insertions(+), 3 deletions(-)


The regression was not detected by PRTS. I guess that is because we don't run S3
tests on PRTS? It would be good to find out why and see what we could to do run
these tests on PRTS.

I'm going on vacation, so I won't really be able to track the status of this
patch and that's why I sent the revert without reporting the bug first. I am
hoping both Daniels will discuss this and decide if they want to merge this or
try to find the proper fix first.


diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
index 07252d8..db07153 100644
--- a/drivers/gpu/drm/i915/i915_params.c
+++ b/drivers/gpu/drm/i915/i915_params.c
@@ -35,7 +35,7 @@ struct i915_params i915 __read_mostly = {
 	.vbt_sdvo_panel_type = -1,
 	.enable_rc6 = -1,
 	.enable_fbc = -1,
-	.enable_execlists = -1,
+	.enable_execlists = 0,
 	.enable_hangcheck = true,
 	.enable_ppgtt = -1,
 	.enable_psr = 0,
@@ -123,7 +123,7 @@ MODULE_PARM_DESC(enable_ppgtt,
 module_param_named(enable_execlists, i915.enable_execlists, int, 0400);
 MODULE_PARM_DESC(enable_execlists,
 	"Override execlists usage. "
-	"(-1=auto [default], 0=disabled, 1=enabled)");
+	"(-1=auto, 0=disabled [default], 1=enabled)");
 
 module_param_named(enable_psr, i915.enable_psr, int, 0600);
 MODULE_PARM_DESC(enable_psr, "Enable PSR (default: false)");
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 7670a0f..f8b96c0 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -212,7 +212,8 @@ static int intel_lr_context_pin(struct intel_engine_cs *ring,
  * @enable_execlists: value of i915.enable_execlists module parameter.
  *
  * Only certain platforms support Execlists (the prerequisites being
- * support for Logical Ring Contexts and Aliasing PPGTT or better).
+ * support for Logical Ring Contexts and Aliasing PPGTT or better),
+ * and only when enabled via module parameter.
  *
  * Return: 1 if Execlists is supported and has to be enabled.
  */
-- 
2.1.4