drm/i915/gt: Leave rps->cur_freq on unpark

Don't override our previous frequency we used after parking, and avoid
continually spiking back to the efficient frequency for mostly idle
workloads. Trust our ability to autotune across a workload switch.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Andi Shyti <andi.shyti@intel.com>
Cc: Lyude Paul <lyude@redhat.com>
Reviewed-by: Andi Shyti <andi.shyti@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200322163225.28791-2-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/gt/intel_rps.c

@@ -187,10 +187,8 @@ static void gen5_rps_init(struct intel_rps *rps)
 		fmax, fmin, fstart);
 
 	rps->min_freq = fmax;
+	rps->efficient_freq = fstart;
 	rps->max_freq = fmin;
-
-	rps->idle_freq = rps->min_freq;
-	rps->cur_freq = rps->idle_freq;
 }
 
 static unsigned long
@@ -713,8 +711,6 @@ static int rps_set(struct intel_rps *rps, u8 val, bool update)
 
 void intel_rps_unpark(struct intel_rps *rps)
 {
-	u8 freq;
-
 	if (!rps->enabled)
 		return;
 
@@ -726,9 +722,10 @@ void intel_rps_unpark(struct intel_rps *rps)
 
 	WRITE_ONCE(rps->active, true);
 
-	freq = max(rps->cur_freq, rps->efficient_freq),
-	freq = clamp(freq, rps->min_freq_softlimit, rps->max_freq_softlimit);
-	intel_rps_set(rps, freq);
+	intel_rps_set(rps,
+		      clamp(rps->cur_freq,
+			    rps->min_freq_softlimit,
+			    rps->max_freq_softlimit));
 
 	rps->last_adj = 0;
 
@@ -1672,7 +1669,9 @@ void intel_rps_init(struct intel_rps *rps)
 	/* Finally allow us to boost to max by default */
 	rps->boost_freq = rps->max_freq;
 	rps->idle_freq = rps->min_freq;
-	rps->cur_freq = rps->idle_freq;
+
+	/* Start in the middle, from here we will autotune based on workload */
+	rps->cur_freq = rps->efficient_freq;
 
 	rps->pm_intrmsk_mbz = 0;