drm/i915: Remove obsolete ringbuffer emission for gen8+

Since removing the module parameter to force selection of ringbuffer
emission for gen8, the code is defunct. Remove it.

To put the difference into perspective, a couple of microbenchmarks
(bdw i7-5557u, 20170324):
                                        ring          execlists
exec continuous nops on all rings:   1.491us            2.223us
exec sequential nops on each ring:  12.508us           53.682us
single nop + sync:                   9.272us           30.291us

vblank_mode=0 glxgears:            ~11000fps           ~9000fps

Since the earlier submission, gen8 ringbuffer submission has fallen
further and further behind in features. So while ringbuffer may hold the
throughput crown, in terms of interactive latency, execlists is much
better. Alas, we have no convenient metrics for such, other than
demonstrating things we can do with execlists but can not using
legacy ringbuffer submission.

We have made a few improvements to lowlevel execlists throughput,
and ringbuffer currently panics on boot! (bdw i7-5557u, 20171026):

                                        ring          execlists
exec continuous nops on all rings:       n/a            1.921us
exec sequential nops on each ring:       n/a           44.621us
single nop + sync:                       n/a           21.953us

vblank_mode=0 glxgears:                  n/a          ~18500fps

References: https://bugs.freedesktop.org/show_bug.cgi?id=87725
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Once-upon-a-time-Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171120205504.21892-2-chris@chris-wilson.co.uk

1 files changed, 0 insertions, 36 deletions

diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c b/drivers/gpu/drm/i915/i915_gpu_error.c
index 7481c8e1b5a8..3d18d67d065f 100644
--- a/drivers/gpu/drm/i915/i915_gpu_error.c
+++ b/drivers/gpu/drm/i915/i915_gpu_error.c
@@ -793,8 +793,6 @@ int i915_error_state_to_str(struct drm_i915_error_state_buf *m,
 				"WA batchbuffer", ee->wa_batchbuffer);
 	}
 
-	print_error_obj(m, NULL, "Semaphores", error->semaphore);
-
 	if (error->overlay)
 		intel_overlay_print_error_state(m, error->overlay);
 
@@ -903,8 +901,6 @@ void __i915_gpu_state_free(struct kref *error_ref)
 			kfree(ee->waiters);
 	}
 
-	i915_error_object_free(error->semaphore);
-
 	for (i = 0; i < ARRAY_SIZE(error->active_bo); i++)
 		kfree(error->active_bo[i]);
 	kfree(error->pinned_bo);
@@ -1116,34 +1112,6 @@ gen8_engine_sync_index(struct intel_engine_cs *engine,
 	return idx;
 }
 
-static void gen8_record_semaphore_state(struct i915_gpu_state *error,
-					struct intel_engine_cs *engine,
-					struct drm_i915_error_engine *ee)
-{
-	struct drm_i915_private *dev_priv = engine->i915;
-	struct intel_engine_cs *to;
-	enum intel_engine_id id;
-
-	if (!error->semaphore)
-		return;
-
-	for_each_engine(to, dev_priv, id) {
-		int idx;
-		u16 signal_offset;
-		u32 *tmp;
-
-		if (engine == to)
-			continue;
-
-		signal_offset =
-			(GEN8_SIGNAL_OFFSET(engine, id) & (PAGE_SIZE - 1)) / 4;
-		tmp = error->semaphore->pages[0];
-		idx = gen8_engine_sync_index(engine, to);
-
-		ee->semaphore_mboxes[idx] = tmp[signal_offset];
-	}
-}
-
 static void gen6_record_semaphore_state(struct intel_engine_cs *engine,
 					struct drm_i915_error_engine *ee)
 {
@@ -1218,7 +1186,6 @@ static void error_record_engine_registers(struct i915_gpu_state *error,
 	if (INTEL_GEN(dev_priv) >= 6) {
 		ee->rc_psmi = I915_READ(RING_PSMI_CTL(engine->mmio_base));
 		if (INTEL_GEN(dev_priv) >= 8) {
-			gen8_record_semaphore_state(error, engine, ee);
 			ee->fault_reg = I915_READ(GEN8_RING_FAULT_REG);
 		} else {
 			gen6_record_semaphore_state(engine, ee);
@@ -1453,9 +1420,6 @@ static void i915_gem_record_rings(struct drm_i915_private *dev_priv,
 	struct i915_ggtt *ggtt = &dev_priv->ggtt;
 	int i;
 
-	error->semaphore =
-		i915_error_object_create(dev_priv, dev_priv->semaphore);
-
 	for (i = 0; i < I915_NUM_ENGINES; i++) {
 		struct intel_engine_cs *engine = dev_priv->engine[i];
 		struct drm_i915_error_engine *ee = &error->engine[i];