drm/i915: Always try to reset the GPU on takeover

When we first introduced the reset to sanitize the GPU on taking over
from the BIOS and before returning control to third parties (the BIOS!),
we restricted it to only systems utilizing HW contexts as we were
uncertain of how stable our reset mechanism truly was. We now have
reasonable coverage across all machines that expose a GPU reset method,
and so we should be safe to sanitize the GPU state everywhere.

v2: We _have_ to skip the reset if it would clobber the display.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190103112104.19561-1-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/i915_drv.c

@@ -2180,7 +2180,7 @@ static int i915_drm_resume_early(struct drm_device *dev)
 
 	intel_power_domains_resume(dev_priv);
 
-	intel_engines_sanitize(dev_priv);
+	intel_engines_sanitize(dev_priv, true);
 
 	enable_rpm_wakeref_asserts(dev_priv);
 

drivers/gpu/drm/i915/i915_gem.c

@@ -3418,8 +3418,7 @@ bool i915_gem_unset_wedged(struct drm_i915_private *i915)
 	i915_retire_requests(i915);
 	GEM_BUG_ON(i915->gt.active_requests);
 
-	if (!intel_gpu_reset(i915, ALL_ENGINES))
-		intel_engines_sanitize(i915);
+	intel_engines_sanitize(i915, false);
 
 	/*
 	 * Undo nop_submit_request. We prevent all new i915 requests from
@@ -5023,8 +5022,6 @@ void __i915_gem_object_release_unless_active(struct drm_i915_gem_object *obj)
 
 void i915_gem_sanitize(struct drm_i915_private *i915)
 {
-	int err;
-
 	GEM_TRACE("\n");
 
 	mutex_lock(&i915->drm.struct_mutex);
@@ -5049,11 +5046,7 @@ void i915_gem_sanitize(struct drm_i915_private *i915)
 	 * it may impact the display and we are uncertain about the stability
 	 * of the reset, so this could be applied to even earlier gen.
 	 */
-	err = -ENODEV;
-	if (INTEL_GEN(i915) >= 5 && intel_has_gpu_reset(i915))
-		err = WARN_ON(intel_gpu_reset(i915, ALL_ENGINES));
-	if (!err)
-		intel_engines_sanitize(i915);
+	intel_engines_sanitize(i915, false);
 
 	intel_uncore_forcewake_put(i915, FORCEWAKE_ALL);
 	intel_runtime_pm_put(i915);

drivers/gpu/drm/i915/i915_pci.c

@@ -82,6 +82,7 @@
 	.display.has_overlay = 1, \
 	.display.overlay_needs_physical = 1, \
 	.display.has_gmch_display = 1, \
+	.gpu_reset_clobbers_display = true, \
 	.hws_needs_physical = 1, \
 	.unfenced_needs_alignment = 1, \
 	.ring_mask = RENDER_RING, \
@@ -122,6 +123,7 @@ static const struct intel_device_info intel_i865g_info = {
 	GEN(3), \
 	.num_pipes = 2, \
 	.display.has_gmch_display = 1, \
+	.gpu_reset_clobbers_display = true, \
 	.ring_mask = RENDER_RING, \
 	.has_snoop = true, \
 	.has_coherent_ggtt = true, \
@@ -198,6 +200,7 @@ static const struct intel_device_info intel_pineview_info = {
 	.num_pipes = 2, \
 	.display.has_hotplug = 1, \
 	.display.has_gmch_display = 1, \
+	.gpu_reset_clobbers_display = true, \
 	.ring_mask = RENDER_RING, \
 	.has_snoop = true, \
 	.has_coherent_ggtt = true, \
@@ -228,6 +231,7 @@ static const struct intel_device_info intel_g45_info = {
 	GEN4_FEATURES,
 	PLATFORM(INTEL_G45),
 	.ring_mask = RENDER_RING | BSD_RING,
+	.gpu_reset_clobbers_display = false,
 };
 
 static const struct intel_device_info intel_gm45_info = {
@@ -237,6 +241,7 @@ static const struct intel_device_info intel_gm45_info = {
 	.display.has_fbc = 1,
 	.display.supports_tv = 1,
 	.ring_mask = RENDER_RING | BSD_RING,
+	.gpu_reset_clobbers_display = false,
 };
 
 #define GEN5_FEATURES \

drivers/gpu/drm/i915/intel_device_info.h

@@ -89,6 +89,7 @@ enum intel_ppgtt {
 	func(is_alpha_support); \
 	/* Keep has_* in alphabetical order */ \
 	func(has_64bit_reloc); \
+	func(gpu_reset_clobbers_display); \
 	func(has_reset_engine); \
 	func(has_fpga_dbg); \
 	func(has_guc); \

drivers/gpu/drm/i915/intel_display.c

@@ -3746,8 +3746,8 @@ __intel_display_resume(struct drm_device *dev,
 
 static bool gpu_reset_clobbers_display(struct drm_i915_private *dev_priv)
 {
-	return intel_has_gpu_reset(dev_priv) &&
-		INTEL_GEN(dev_priv) < 5 && !IS_G4X(dev_priv);
+	return (INTEL_INFO(dev_priv)->gpu_reset_clobbers_display &&
+		intel_has_gpu_reset(dev_priv));
 }
 
 void intel_prepare_reset(struct drm_i915_private *dev_priv)

drivers/gpu/drm/i915/intel_engine_cs.c

@@ -1043,22 +1043,34 @@ void intel_engines_reset_default_submission(struct drm_i915_private *i915)
 		engine->set_default_submission(engine);
 }
 
+static bool reset_engines(struct drm_i915_private *i915)
+{
+	if (INTEL_INFO(i915)->gpu_reset_clobbers_display)
+		return false;
+
+	return intel_gpu_reset(i915, ALL_ENGINES) == 0;
+}
+
 /**
  * intel_engines_sanitize: called after the GPU has lost power
  * @i915: the i915 device
+ * @force: ignore a failed reset and sanitize engine state anyway
  *
  * Anytime we reset the GPU, either with an explicit GPU reset or through a
  * PCI power cycle, the GPU loses state and we must reset our state tracking
  * to match. Note that calling intel_engines_sanitize() if the GPU has not
  * been reset results in much confusion!
  */
-void intel_engines_sanitize(struct drm_i915_private *i915)
+void intel_engines_sanitize(struct drm_i915_private *i915, bool force)
 {
 	struct intel_engine_cs *engine;
 	enum intel_engine_id id;
 
 	GEM_TRACE("\n");
 
+	if (!reset_engines(i915) && !force)
+		return;
+
 	for_each_engine(engine, i915, id) {
 		if (engine->reset.reset)
 			engine->reset.reset(engine, NULL);

drivers/gpu/drm/i915/intel_ringbuffer.h

@@ -1019,7 +1019,7 @@ gen8_emit_ggtt_write(u32 *cs, u32 value, u32 gtt_offset)
 	return cs;
 }
 
-void intel_engines_sanitize(struct drm_i915_private *i915);
+void intel_engines_sanitize(struct drm_i915_private *i915, bool force);
 
 bool intel_engine_is_idle(struct intel_engine_cs *engine);
 bool intel_engines_are_idle(struct drm_i915_private *dev_priv);

drivers/gpu/drm/i915/selftests/i915_gem.c

@@ -121,7 +121,7 @@ static void pm_resume(struct drm_i915_private *i915)
 	 */
 	intel_runtime_pm_get(i915);
 
-	intel_engines_sanitize(i915);
+	intel_engines_sanitize(i915, false);
 	i915_gem_sanitize(i915);
 	i915_gem_resume(i915);