[Intel-gfx] [RFC 23/39] drm/i915: Added a module parameter for allowing scheduler overrides

[John.C.Harrison at Intel.com]

From: John Harrison <John.C.Harrison at Intel.com>

It can be useful to be able to disable certain features (e.g. the entire
scheduler) via a module parameter for debugging purposes. A parameter has the
advantage of not being a compile time switch but without implying that it can be
changed dynamically at runtime.

Change-Id: I92f4c832be88f5b34b49b90d6a9903fac68f7004
For: VIZ-1587
Signed-off-by: John Harrison <John.C.Harrison at Intel.com>
---
 drivers/gpu/drm/i915/i915_drv.h       | 1 +
 drivers/gpu/drm/i915/i915_params.c    | 4 ++++
 drivers/gpu/drm/i915/i915_scheduler.c | 7 +++++--
 drivers/gpu/drm/i915/i915_scheduler.h | 5 +++++
 4 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index e9e0736..30552cc 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2664,6 +2664,7 @@ struct i915_params {
 	bool verbose_state_checks;
 	bool nuclear_pageflip;
 	int edp_vswing;
+	int scheduler_override;
 };
 extern struct i915_params i915 __read_mostly;
 
diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
index 7983fe4..a5320ff 100644
--- a/drivers/gpu/drm/i915/i915_params.c
+++ b/drivers/gpu/drm/i915/i915_params.c
@@ -53,6 +53,7 @@ struct i915_params i915 __read_mostly = {
 	.verbose_state_checks = 1,
 	.nuclear_pageflip = 0,
 	.edp_vswing = 0,
+	.scheduler_override = 1,
 };
 
 module_param_named(modeset, i915.modeset, int, 0400);
@@ -186,3 +187,6 @@ MODULE_PARM_DESC(edp_vswing,
 		 "Ignore/Override vswing pre-emph table selection from VBT "
 		 "(0=use value from vbt [default], 1=low power swing(200mV),"
 		 "2=default swing(400mV))");
+
+module_param_named(scheduler_override, i915.scheduler_override, int, 0600);
+MODULE_PARM_DESC(scheduler_override, "Scheduler override mask (0 = none, 1 = direct submission [default])");
diff --git a/drivers/gpu/drm/i915/i915_scheduler.c b/drivers/gpu/drm/i915/i915_scheduler.c
index 3155f42..224c8b4 100644
--- a/drivers/gpu/drm/i915/i915_scheduler.c
+++ b/drivers/gpu/drm/i915/i915_scheduler.c
@@ -44,6 +44,9 @@ bool i915_scheduler_is_enabled(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
 
+	if (i915.scheduler_override & i915_so_direct_submit)
+		return false;
+
 	return dev_priv->scheduler != NULL;
 }
 
@@ -92,7 +95,7 @@ int i915_scheduler_queue_execbuffer(struct i915_scheduler_queue_entry *qe)
 
 	BUG_ON(!scheduler);
 
-	if (1/*i915.scheduler_override & i915_so_direct_submit*/) {
+	if (i915.scheduler_override & i915_so_direct_submit) {
 		int ret;
 
 		qe->scheduler_index = scheduler->index++;
@@ -466,7 +469,7 @@ int i915_scheduler_handle_irq(struct intel_engine_cs *ring)
 
 	seqno = ring->get_seqno(ring, false);
 
-	if (1/*i915.scheduler_override & i915_so_direct_submit*/)
+	if (i915.scheduler_override & i915_so_direct_submit)
 		return 0;
 
 	if (seqno == scheduler->last_irq_seqno[ring->id]) {
diff --git a/drivers/gpu/drm/i915/i915_scheduler.h b/drivers/gpu/drm/i915/i915_scheduler.h
index b440e62..7d743c9 100644
--- a/drivers/gpu/drm/i915/i915_scheduler.h
+++ b/drivers/gpu/drm/i915/i915_scheduler.h
@@ -89,6 +89,11 @@ enum {
 	i915_sf_submitting          = (1 << 1),
 };
 
+/* Options for 'scheduler_override' module parameter: */
+enum {
+	i915_so_direct_submit       = (1 << 0),
+};
+
 bool        i915_scheduler_is_enabled(struct drm_device *dev);
 int         i915_scheduler_init(struct drm_device *dev);
 int         i915_scheduler_closefile(struct drm_device *dev,
-- 
1.9.1