From: Rodrigo Vivi <rodrigo.vivi@intel.com>
Date: Mon, 1 Feb 2016 20:02:07 +0000 (-0800)
Subject: drm/i915: Add PSR main link standby support back
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=60e5ffe329b090155ec860e2f31dc8d505ec7acd;p=linux-beck.git

drm/i915: Add PSR main link standby support back

Link standby support has been deprecated with 'commit 89251b177
("drm/i915: PSR: deprecate link_standby support for core platforms.")'

The reason for that is that main link in full off offers more power
savings and on HSW and BDW implementations on source side had known
bugs with link standby.

However that same HSD report only mentions BDW and HSW and tells that
a fix was going to new platforms. Since on Skylake link standby
didn't cause the bad blank flickering screens seen on HSW and BDW
let's respect VBT again for this and future platforms.

Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
---

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 863012a2602e..ec0c2a05eed6 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -2583,6 +2583,10 @@ static int i915_edp_psr_status(struct seq_file *m, void *data)
 				enabled = true;
 		}
 	}
+
+	seq_printf(m, "Main link in standby mode: %s\n",
+		   yesno(dev_priv->psr.link_standby));
+
 	seq_printf(m, "HW Enabled & Active bit: %s", yesno(enabled));
 
 	if (!HAS_DDI(dev))
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index c921ad8e15a7..65a2cd04bc8f 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1007,6 +1007,7 @@ struct i915_psr {
 	unsigned busy_frontbuffer_bits;
 	bool psr2_support;
 	bool aux_frame_sync;
+	bool link_standby;
 };
 
 enum intel_pch {
diff --git a/drivers/gpu/drm/i915/intel_psr.c b/drivers/gpu/drm/i915/intel_psr.c
index 3c80b86e45f8..b99a105ae58b 100644
--- a/drivers/gpu/drm/i915/intel_psr.c
+++ b/drivers/gpu/drm/i915/intel_psr.c
@@ -225,7 +225,12 @@ static void hsw_psr_enable_sink(struct intel_dp *intel_dp)
 		   (aux_clock_divider << DP_AUX_CH_CTL_BIT_CLOCK_2X_SHIFT));
 	}
 
-	drm_dp_dpcd_writeb(&intel_dp->aux, DP_PSR_EN_CFG, DP_PSR_ENABLE);
+	if (dev_priv->psr.link_standby)
+		drm_dp_dpcd_writeb(&intel_dp->aux, DP_PSR_EN_CFG,
+				   DP_PSR_ENABLE | DP_PSR_MAIN_LINK_ACTIVE);
+	else
+		drm_dp_dpcd_writeb(&intel_dp->aux, DP_PSR_EN_CFG,
+				   DP_PSR_ENABLE);
 }
 
 static void vlv_psr_enable_source(struct intel_dp *intel_dp)
@@ -280,6 +285,9 @@ static void hsw_psr_enable_source(struct intel_dp *intel_dp)
 	if (IS_HASWELL(dev))
 		val |= EDP_PSR_MIN_LINK_ENTRY_TIME_8_LINES;
 
+	if (dev_priv->psr.link_standby)
+		val |= EDP_PSR_LINK_STANDBY;
+
 	I915_WRITE(EDP_PSR_CTL, val |
 		   max_sleep_time << EDP_PSR_MAX_SLEEP_TIME_SHIFT |
 		   idle_frames << EDP_PSR_IDLE_FRAME_SHIFT |
@@ -334,12 +342,6 @@ static bool intel_psr_match_conditions(struct intel_dp *intel_dp)
 		return false;
 	}
 
-	if (!IS_VALLEYVIEW(dev) && !IS_CHERRYVIEW(dev) &&
-	    dev_priv->vbt.psr.full_link) {
-		DRM_DEBUG_KMS("PSR condition failed: Link Standby requested/needed but not supported on this platform\n");
-		return false;
-	}
-
 	dev_priv->psr.source_ok = true;
 	return true;
 }
@@ -770,6 +772,16 @@ void intel_psr_init(struct drm_device *dev)
 	dev_priv->psr_mmio_base = IS_HASWELL(dev_priv) ?
 		HSW_EDP_PSR_BASE : BDW_EDP_PSR_BASE;
 
+	if (IS_HASWELL(dev) || IS_BROADWELL(dev))
+		/* HSW and BDW require workarounds that we don't implement. */
+		dev_priv->psr.link_standby = false;
+	else if (IS_VALLEYVIEW(dev) || IS_CHERRYVIEW(dev))
+		/* On VLV and CHV only standby mode is supported. */
+		dev_priv->psr.link_standby = true;
+	else
+		/* For new platforms let's respect VBT back again */
+		dev_priv->psr.link_standby = dev_priv->vbt.psr.full_link;
+
 	INIT_DELAYED_WORK(&dev_priv->psr.work, intel_psr_work);
 	mutex_init(&dev_priv->psr.lock);
 }