[PATCH] drm/i915: boost GPU and CPU freq when leaving idle

[Jesse Barnes <jbarnes@virtuousgeek.org>]

Coming out of idle is usually due to some sort of user input (swiping a
screen, clicking a button) and often results in some sort of graphical
animation.  To prevent stutter for a CPU or GPU intensive animation,
boost the GPU and CPU freq to the maximum to get the first frame out as
quickly as possible.  The normal CPU and GPU frequency management code
will take over from there and (hopefully) clock down to save power as
needed if the max frequencies aren't required.

This could probably be done more cleanly, and possibly without another
uncached read in the execbuf path if we tracked idleness elsewhere.  I'm
also unsure about the cpufreq calls; I don't really know if this will do
what I want...

Requested-by: Owen Taylor <otaylor@gtk.org>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
---
 drivers/gpu/drm/i915/i915_gem_execbuffer.c |   24 ++++++++++++++++++++++++
 drivers/gpu/drm/i915/intel_drv.h           |    2 ++
 drivers/gpu/drm/i915/intel_pm.c            |   24 ++++++++++++++++++++++++
 3 files changed, 50 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index 87a3227..fd4b4cb 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -26,6 +26,7 @@
  *
  */
 
+#include <linux/cpufreq.h>
 #include <drm/drmP.h>
 #include <drm/i915_drm.h>
 #include "i915_drv.h"
@@ -1058,6 +1059,29 @@ i915_gem_do_execbuffer(struct drm_device *dev, void *data,
 			goto err;
 	}
 
+	/*
+	 * Before dispatching, check if the GPU is busy.  If not,
+	 * boost the GPU and CPU freqs to maximum to make sure
+	 * animation startup is smooth.
+	 */
+	if (intel_gpu_idle(dev)) {
+		struct cpufreq_policy *policy;
+		unsigned int cpu = smp_processor_id();
+		int cpu_freq;
+
+		mutex_lock(&dev_priv->rps.hw_lock);
+		if (IS_VALLEYVIEW(dev))
+			valleyview_set_rps(dev, dev_priv->rps.max_delay);
+		else if (IS_GEN6(dev) || IS_GEN7(dev))
+			gen6_set_rps(dev, dev_priv->rps.max_delay);
+		mutex_unlock(&dev_priv->rps.hw_lock);
+
+		policy = cpufreq_cpu_get(cpu);
+		cpu_freq = cpufreq_quick_get_max(cpu);
+
+		cpufreq_driver_target(policy, cpu_freq, CPUFREQ_RELATION_H);
+	}
+
 	exec_start = batch_obj->gtt_offset + args->batch_start_offset;
 	exec_len = args->batch_len;
 	if (cliprects) {
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 6f7f33e..e84176b 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -840,4 +840,6 @@ extern bool intel_set_pch_fifo_underrun_reporting(struct drm_device *dev,
 						 enum transcoder pch_transcoder,
 						 bool enable);
 
+extern bool intel_gpu_idle(struct drm_device *dev);
+
 #endif /* __INTEL_DRV_H__ */
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index e809c57..7ad2764 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -5621,3 +5621,27 @@ int vlv_freq_opcode(int ddr_freq, int val)
 	return val;
 }
 
+bool intel_gpu_idle(struct drm_device *dev)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+
+	if (IS_VALLEYVIEW(dev)) {
+		u32 gtlc_pw_status;
+
+		gtlc_pw_status = I915_READ(VLV_GTLC_PW_STATUS);
+		if (gtlc_pw_status & (1<<7))
+			return false;
+		else
+			return true;
+	} else if (IS_GEN6(dev) || IS_GEN7(dev)) {
+		u32 gt_core_status;
+
+		gt_core_status = I915_READ(GEN6_GT_CORE_STATUS);
+		if (gt_core_status & GEN6_CORE_CPD_STATE_MASK)
+			return true;
+		else
+			return false;
+	} else {
+		return false;
+	}
+}
-- 
1.7.9.5