From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Wed, 24 Jan 2018 11:36:07 +0000
Subject: drm/i915: Track the number of times we have woken the GPU up
Git-commit: 6f56103d7e95f96568a460493ff6c0ced45f538b
Patch-mainline: v4.17-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166

By counting the number of times we have woken up, we have a very simple
means of defining an epoch, which will come in handy if we want to
perform deferred tasks at the end of an epoch (i.e. while we are going
to sleep) without imposing on the next activity cycle.

v2: No reason to specify precise number of bits here.
v3: Take Tvrtko's advice and reserve 0 as an invalid epoch.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180124113608.14909-1-chris@chris-wilson.co.uk

Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/gpu/drm/i915/i915_debugfs.c     |    7 ++++---
 drivers/gpu/drm/i915/i915_drv.h         |    6 ++++++
 drivers/gpu/drm/i915/i915_gem_request.c |    2 ++
 3 files changed, 12 insertions(+), 3 deletions(-)

--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -2716,7 +2716,8 @@ static int i915_runtime_pm_status(struct
 	if (!HAS_RUNTIME_PM(dev_priv))
 		seq_puts(m, "Runtime power management not supported\n");
 
-	seq_printf(m, "GPU idle: %s\n", yesno(!dev_priv->gt.awake));
+	seq_printf(m, "GPU idle: %s (epoch %u)\n",
+		   yesno(!dev_priv->gt.awake), dev_priv->gt.epoch);
 	seq_printf(m, "IRQs disabled: %s\n",
 		   yesno(!intel_irqs_enabled(dev_priv)));
 #ifdef CONFIG_PM
@@ -3149,8 +3150,8 @@ static int i915_engine_info(struct seq_f
 
 	intel_runtime_pm_get(dev_priv);
 
-	seq_printf(m, "GT awake? %s\n",
-		   yesno(dev_priv->gt.awake));
+	seq_printf(m, "GT awake? %s (epoch %u)\n",
+		   yesno(dev_priv->gt.awake), dev_priv->gt.epoch);
 	seq_printf(m, "Global active requests: %d\n",
 		   dev_priv->gt.active_requests);
 	seq_printf(m, "CS timestamp frequency: %u kHz\n",
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2314,6 +2314,12 @@ struct drm_i915_private {
 		bool awake;
 
 		/**
+		 * The number of times we have woken up.
+		 */
+		unsigned int epoch;
+#define I915_EPOCH_INVALID 0
+
+		/**
 		 * We leave the user IRQ off as much as possible,
 		 * but this means that requests will finish and never
 		 * be retired once the system goes idle. Set a timer to
--- a/drivers/gpu/drm/i915/i915_gem_request.c
+++ b/drivers/gpu/drm/i915/i915_gem_request.c
@@ -274,6 +274,8 @@ static void mark_busy(struct drm_i915_pr
 	intel_display_power_get(i915, POWER_DOMAIN_GT_IRQ);
 
 	i915->gt.awake = true;
+	if (unlikely(++i915->gt.epoch == 0)) /* keep 0 as invalid */
+		i915->gt.epoch = 1;
 
 	intel_enable_gt_powersave(i915);
 	i915_update_gfx_val(i915);