[Intel-gfx] [PATCH v6 20/34] drm/i915: Added a module parameter to allow the scheduler to be disabled

[John.C.Harrison at Intel.com]

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

It can be useful to be able to disable the GPU scheduler via a module
parameter for debugging purposes.

v5: Converted from a multi-feature 'overrides' mask to a single
'enable' boolean. Further features (e.g. pre-emption) will now be
separate 'enable' booleans added later. [Chris Wilson]

v6: Moved scheduler parameter declaration to correct place in
i915_params struct. [review feedback from Matt Roper]

For: VIZ-1587
Signed-off-by: John Harrison <John.C.Harrison at Intel.com>
Reviewed-by: Jesse Barnes <jbarnes at virtuousgeek.org>
CC: Matt Roper <matthew.d.roper at intel.com>
---
 drivers/gpu/drm/i915/i915_params.c    | 4 ++++
 drivers/gpu/drm/i915/i915_params.h    | 1 +
 drivers/gpu/drm/i915/i915_scheduler.c | 5 ++++-
 3 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
index 1285063..45288a2 100644
--- a/drivers/gpu/drm/i915/i915_params.c
+++ b/drivers/gpu/drm/i915/i915_params.c
@@ -58,6 +58,7 @@ struct i915_params i915 __read_mostly = {
 	.guc_log_level = -1,
 	.enable_dp_mst = true,
 	.inject_load_failure = 0,
+	.enable_scheduler = 0,
 };
 
 module_param_named(modeset, i915.modeset, int, 0400);
@@ -210,3 +211,6 @@ MODULE_PARM_DESC(enable_dp_mst,
 module_param_named_unsafe(inject_load_failure, i915.inject_load_failure, uint, 0400);
 MODULE_PARM_DESC(inject_load_failure,
 	"Force an error after a number of failure check points (0:disabled (default), N:force failure at the Nth failure check point)");
+
+module_param_named_unsafe(enable_scheduler, i915.enable_scheduler, int, 0600);
+MODULE_PARM_DESC(enable_scheduler, "Enable scheduler (0 = disable [default], 1 = enable)");
diff --git a/drivers/gpu/drm/i915/i915_params.h b/drivers/gpu/drm/i915/i915_params.h
index 02bc278..44b08b3 100644
--- a/drivers/gpu/drm/i915/i915_params.h
+++ b/drivers/gpu/drm/i915/i915_params.h
@@ -50,6 +50,7 @@ struct i915_params {
 	int mmio_debug;
 	int edp_vswing;
 	unsigned int inject_load_failure;
+	int enable_scheduler;
 	/* leave bools at the end to not create holes */
 	bool enable_hangcheck;
 	bool fastboot;
diff --git a/drivers/gpu/drm/i915/i915_scheduler.c b/drivers/gpu/drm/i915/i915_scheduler.c
index 9c3150a..13084fb 100644
--- a/drivers/gpu/drm/i915/i915_scheduler.c
+++ b/drivers/gpu/drm/i915/i915_scheduler.c
@@ -42,6 +42,9 @@ bool i915_scheduler_is_enabled(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = to_i915(dev);
 
+	if (!i915.enable_scheduler)
+		return false;
+
 	return dev_priv->scheduler != NULL;
 }
 
@@ -593,7 +596,7 @@ int i915_scheduler_queue_execbuffer(struct i915_scheduler_queue_entry *qe)
 	int incomplete;
 
 	/* Bypass the scheduler and send the buffer immediately? */
-	if (1/*!i915.enable_scheduler*/)
+	if (!i915.enable_scheduler)
 		return i915_scheduler_queue_execbuffer_bypass(qe);
 
 	node = kmalloc(sizeof(*node), GFP_KERNEL);
-- 
1.9.1