[Intel-gfx] [PATCH 3/3] drm/i915: Only apply the jump to the "efficient RPS" frequency on startup

[Chris Wilson]

Currently we apply the jump to rpe if we are below it and the GPU needs
more power. For some GPUs, the rpe is 75% of the maximum range causing
us to dramatically overshoot low power applications *and* unable to
reach the low frequency that can most efficiently deliver their
workload.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_irq.c |  8 --------
 drivers/gpu/drm/i915/intel_pm.c | 11 +++++++++--
 2 files changed, 9 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index d7f9e97ff8d8..b8e0374bc9f5 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -1206,14 +1206,6 @@ static void gen6_pm_rps_work(struct work_struct *work)
 
 		if (new_delay >= dev_priv->rps.max_freq_softlimit)
 			adj = 0;
-		/*
-		 * For better performance, jump directly
-		 * to RPe if we're below it.
-		 */
-		if (new_delay < dev_priv->rps.efficient_freq - adj) {
-			new_delay = dev_priv->rps.efficient_freq;
-			adj = 0;
-		}
 	} else if (client_boost || any_waiters(dev_priv)) {
 		adj = 0;
 	} else if (pm_iir & GEN6_PM_RP_DOWN_TIMEOUT) {
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 2bf47f15eebe..77c454df8a3e 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -5019,6 +5019,8 @@ void gen6_rps_busy(struct drm_i915_private *dev_priv)
 {
 	mutex_lock(&dev_priv->rps.hw_lock);
 	if (dev_priv->rps.enabled) {
+		u8 freq;
+
 		if (dev_priv->pm_rps_events & (GEN6_PM_RP_DOWN_EI_EXPIRED | GEN6_PM_RP_UP_EI_EXPIRED))
 			gen6_rps_reset_ei(dev_priv);
 		I915_WRITE(GEN6_PMINTRMSK,
@@ -5026,9 +5028,14 @@ void gen6_rps_busy(struct drm_i915_private *dev_priv)
 
 		gen6_enable_rps_interrupts(dev_priv);
 
-		/* Ensure we start at the user's desired frequency */
+		/* Use the user's desired frequency as a guide, but for better
+		 * performance, jump directly to RPe as our starting frequency.
+		 */
+		freq = max(dev_priv->rps.cur_freq,
+			   dev_priv->rps.efficient_freq);
+
 		if (intel_set_rps(dev_priv,
-				  clamp(dev_priv->rps.cur_freq,
+				  clamp(freq,
 					dev_priv->rps.min_freq_softlimit,
 					dev_priv->rps.max_freq_softlimit)))
 			DRM_DEBUG_DRIVER("Failed to set idle frequency\n");
-- 
2.11.0