[Intel-gfx] [PATCH 2/2] drm/i915: Add a module parameter to enable execlists

[Damien Lespiau]

Execlist are relatively new, and so it'd be wise to be able to merge
that support disabled by default while still allowing a module parameter
to enable that feature.

Even if we end up enabling execlists by default, it'll be handy to be
able to switch back to ring submission to debug subtle problems that
will inevitably arise.

Signed-off-by: Damien Lespiau <damien.lespiau at intel.com>
---
 drivers/gpu/drm/i915/i915_drv.h    | 1 +
 drivers/gpu/drm/i915/i915_gem.c    | 3 +++
 drivers/gpu/drm/i915/i915_params.c | 6 ++++++
 3 files changed, 10 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 34a8fe5..8f0d27a 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2013,6 +2013,7 @@ struct i915_params {
 	int enable_rc6;
 	int enable_fbc;
 	int enable_ppgtt;
+	int enable_execlists;
 	int enable_psr;
 	unsigned int preliminary_hw_support;
 	int disable_power_well;
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 998f647..57ef2a7 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -4462,6 +4462,9 @@ err_out:
 
 static bool enable_execlists(struct drm_device *dev)
 {
+	if (!i915.enable_execlists)
+		return false;
+
 	return HAS_LOGICAL_RING_CONTEXTS(dev) && USES_PPGTT(dev);
 }
 
diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
index d1d7980..32112f2 100644
--- a/drivers/gpu/drm/i915/i915_params.c
+++ b/drivers/gpu/drm/i915/i915_params.c
@@ -37,6 +37,7 @@ struct i915_params i915 __read_mostly = {
 	.enable_fbc = -1,
 	.enable_hangcheck = true,
 	.enable_ppgtt = -1,
+	.enable_execlists = 0,
 	.enable_psr = 0,
 	.preliminary_hw_support = IS_ENABLED(CONFIG_DRM_I915_PRELIMINARY_HW_SUPPORT),
 	.disable_power_well = 1,
@@ -115,6 +116,11 @@ MODULE_PARM_DESC(enable_ppgtt,
 	"Override PPGTT usage. "
 	"(-1=auto [default], 0=disabled, 1=aliasing, 2=full)");
 
+module_param_named(enable_execlists, i915.enable_execlists, int, 0400);
+MODULE_PARM_DESC(enable_execlists,
+	"Override execlists usage. "
+	"(-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)");
 
-- 
1.8.3.1