[PATCH] drm/i915: Force PSR exit before disabling PSR

[Jouni Högander]

FIFO underruns are observed when disabling PSR. We are Suspecting
this is somehow dependent on PSR state machine. This patch is forcing
PSR exit before disabling it.

Signed-off-by: Jouni Högander <jouni.hogander at intel.com>
---
 drivers/gpu/drm/i915/display/intel_psr.c | 28 ++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_psr.c b/drivers/gpu/drm/i915/display/intel_psr.c
index e6a870641cd2..f64cfbf32457 100644
--- a/drivers/gpu/drm/i915/display/intel_psr.c
+++ b/drivers/gpu/drm/i915/display/intel_psr.c
@@ -1364,6 +1364,33 @@ static void intel_psr_disable_locked(struct intel_dp *intel_dp)
 	intel_dp->psr.psr2_sel_fetch_cff_enabled = false;
 }
 
+static void psr_force_hw_tracking_exit(struct intel_dp *intel_dp)
+{
+	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
+
+	if (intel_dp->psr.psr2_sel_fetch_enabled)
+		intel_de_write(dev_priv,
+			       PSR2_MAN_TRK_CTL(intel_dp->psr.transcoder),
+			       man_trk_ctl_enable_bit_get(dev_priv) |
+			       man_trk_ctl_partial_frame_bit_get(dev_priv) |
+			       man_trk_ctl_single_full_frame_bit_get(dev_priv));
+
+	/*
+	 * Display WA #0884: skl+
+	 * This documented WA for bxt can be safely applied
+	 * broadly so we can force HW tracking to exit PSR
+	 * instead of disabling and re-enabling.
+	 * Workaround tells us to write 0 to CUR_SURFLIVE_A,
+	 * but it makes more sense write to the current active
+	 * pipe.
+	 *
+	 * This workaround do not exist for platforms with display 10 or newer
+	 * but testing proved that it works for up display 13, for newer
+	 * than that testing will be needed.
+	 */
+	intel_de_write(dev_priv, CURSURFLIVE(intel_dp->psr.pipe), 0);
+}
+
 /**
  * intel_psr_disable - Disable PSR
  * @intel_dp: Intel DP
@@ -1384,6 +1411,7 @@ void intel_psr_disable(struct intel_dp *intel_dp,
 
 	mutex_lock(&intel_dp->psr.lock);
 
+	psr_force_hw_tracking_exit(intel_dp);
 	intel_psr_disable_locked(intel_dp);
 
 	mutex_unlock(&intel_dp->psr.lock);
-- 
2.25.1