[Intel-gfx] [PATCH v2 11/11] drm/i915/psr: Set the right frames values

[José Roberto de Souza]

EDP_PSR2_FRAME_BEFORE_SU() is the number of frames that PSR2 HW will
wait before enter in PSR2 activation state, important to note here is
that it will wait for X frames not X idle frames.
So lets reuse the previous approch to get the maximum number of
frames between 6 and sink_sync_latency to enter in PSR2 activation
state and just remove the VBT idle_frames.

And EDP_PSR2_FRAME_BEFORE_SU() is the number of idle frames that
PSR2 HW will wait before enter in PSR2 deep sleep when PSR2 is
active.
Important note here is that HW will need to go to PSR2 idle state
every time it exits PSR2 deep sleep, so avoid as much as possible
deep sleep will provide in overal more power savings as PSR2 sleep
will save some power as memory will not be read in the idle frames
and screen will be partialy updated without exit PSR2.

Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan at intel.com>
Signed-off-by: José Roberto de Souza <jose.souza at intel.com>
---
 drivers/gpu/drm/i915/intel_psr.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_psr.c b/drivers/gpu/drm/i915/intel_psr.c
index 0257dbcf9384..36c2eb27ed8d 100644
--- a/drivers/gpu/drm/i915/intel_psr.c
+++ b/drivers/gpu/drm/i915/intel_psr.c
@@ -489,18 +489,20 @@ static void hsw_activate_psr2(struct intel_dp *intel_dp)
 
 	/* Let's use 6 as the minimum to cover all known cases including the
 	 * off-by-one issue that HW has in some cases.
+	 * sink_sync_latency of 8 means source has to wait for more than 8
+	 * frames, so sink_sync_latency + 1.
 	 */
-	int idle_frames = max(6, dev_priv->vbt.psr.idle_frames);
+	val = max(6, dev_priv->psr.sink_sync_latency + 1);
+	val = min_t(u32, val, EDP_PSR2_FRAME_BEFORE_SU_MAX);
+	val = EDP_PSR2_FRAME_BEFORE_SU(val);
 
-	idle_frames = max(idle_frames, dev_priv->psr.sink_sync_latency + 1);
-	val = idle_frames << EDP_PSR2_IDLE_FRAME_SHIFT;
+	/* Avoid deep sleep as much as possible to avoid PSR2 idle state */
+	val |= EDP_PSR2_IDLE_FRAME(EDP_PSR2_IDLE_FRAME_MAX);
 
 	val |= EDP_PSR2_ENABLE | EDP_SU_TRACK_ENABLE;
 	if (INTEL_GEN(dev_priv) >= 10 || IS_GEMINILAKE(dev_priv))
 		val |= EDP_Y_COORDINATE_ENABLE;
 
-	val |= EDP_PSR2_FRAME_BEFORE_SU(dev_priv->psr.sink_sync_latency + 1);
-
 	if (dev_priv->vbt.psr.tp2_tp3_wakeup_time_us >= 0 &&
 	    dev_priv->vbt.psr.tp2_tp3_wakeup_time_us <= 50)
 		val |= EDP_PSR2_TP2_TIME_50us;
-- 
2.19.2