drm/i915: Match all PSR mode entry conditions before enabling it.

v2: Prefer seq_puts to seq_printf by Paulo Zanoni.
v3: small changes like avoiding calling dp_to_dig_port twice as noticed by
    Paulo Zanoni.
v4: Avoiding reading non-existent registers - noticed by Paulo
    on first psr debugfs patch.
v5: Accepting more suggestions from Paulo:
    * check sw interlace flag instead of i915_read
    * introduce PSR_S3D_ENABLED to avoid forgeting it whenever added.

Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@gmail.com>
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: Shobhit Kumar <shobhit.kumar@intel.com>
[danvet: Fix up debugfs output (spotted by Paulo) and rip out the
power well check since we really can't do that in a race-free manner,
so it's bogus.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_debugfs.c

@@ -1550,17 +1550,49 @@ static int i915_edp_psr_status(struct seq_file *m, void *data)
 	struct drm_info_node *node = m->private;
 	struct drm_device *dev = node->minor->dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
-	u32 psrctl, psrstat, psrperf;
+	u32 psrstat, psrperf;
 
 	if (!IS_HASWELL(dev)) {
 		seq_puts(m, "PSR not supported on this platform\n");
+	} else if (IS_HASWELL(dev) && I915_READ(EDP_PSR_CTL) & EDP_PSR_ENABLE) {
+		seq_puts(m, "PSR enabled\n");
+	} else {
+		seq_puts(m, "PSR disabled: ");
+		switch (dev_priv->no_psr_reason) {
+		case PSR_NO_SOURCE:
+			seq_puts(m, "not supported on this platform");
+			break;
+		case PSR_NO_SINK:
+			seq_puts(m, "not supported by panel");
+			break;
+		case PSR_CRTC_NOT_ACTIVE:
+			seq_puts(m, "crtc not active");
+			break;
+		case PSR_PWR_WELL_ENABLED:
+			seq_puts(m, "power well enabled");
+			break;
+		case PSR_NOT_TILED:
+			seq_puts(m, "not tiled");
+			break;
+		case PSR_SPRITE_ENABLED:
+			seq_puts(m, "sprite enabled");
+			break;
+		case PSR_S3D_ENABLED:
+			seq_puts(m, "stereo 3d enabled");
+			break;
+		case PSR_INTERLACED_ENABLED:
+			seq_puts(m, "interlaced enabled");
+			break;
+		case PSR_HSW_NOT_DDIA:
+			seq_puts(m, "HSW ties PSR to DDI A (eDP)");
+			break;
+		default:
+			seq_puts(m, "unknown reason");
+		}
+		seq_puts(m, "\n");
 		return 0;
 	}
 
-	psrctl = I915_READ(EDP_PSR_CTL);
-	seq_printf(m, "PSR Enabled: %s\n",
-		   yesno(psrctl & EDP_PSR_ENABLE));
-
 	psrstat = I915_READ(EDP_PSR_STATUS_CTL);
 
 	seq_puts(m, "PSR Current State: ");

drivers/gpu/drm/i915/i915_drv.h

@@ -593,6 +593,17 @@ struct i915_fbc {
 	} no_fbc_reason;
 };
 
+enum no_psr_reason {
+	PSR_NO_SOURCE, /* Not supported on platform */
+	PSR_NO_SINK, /* Not supported by panel */
+	PSR_CRTC_NOT_ACTIVE,
+	PSR_PWR_WELL_ENABLED,
+	PSR_NOT_TILED,
+	PSR_SPRITE_ENABLED,
+	PSR_S3D_ENABLED,
+	PSR_INTERLACED_ENABLED,
+	PSR_HSW_NOT_DDIA,
+};
 
 enum intel_pch {
 	PCH_NONE = 0,	/* No PCH present */
@@ -1173,6 +1184,8 @@ typedef struct drm_i915_private {
 	/* Haswell power well */
 	struct i915_power_well power_well;
 
+	enum no_psr_reason no_psr_reason;
+
 	struct i915_gpu_error gpu_error;
 
 	struct drm_i915_gem_object *vlv_pctx;

drivers/gpu/drm/i915/i915_reg.h

@@ -4150,6 +4150,13 @@
 #define HSW_TVIDEO_DIP_VSC_DATA(trans) \
 	 _TRANSCODER(trans, HSW_VIDEO_DIP_VSC_DATA_A, HSW_VIDEO_DIP_VSC_DATA_B)
 
+#define HSW_STEREO_3D_CTL_A	0x70020
+#define   S3D_ENABLE		(1<<31)
+#define HSW_STEREO_3D_CTL_B	0x71020
+
+#define HSW_STEREO_3D_CTL(trans) \
+	_TRANSCODER(trans, HSW_STEREO_3D_CTL_A, HSW_STEREO_3D_CTL_A)
+
 #define _PCH_TRANS_HTOTAL_B          0xe1000
 #define _PCH_TRANS_HBLANK_B          0xe1004
 #define _PCH_TRANS_HSYNC_B           0xe1008

drivers/gpu/drm/i915/intel_dp.c

@@ -1492,11 +1492,76 @@ static void intel_edp_psr_enable_source(struct intel_dp *intel_dp)
 		   EDP_PSR_ENABLE);
 }
 
+static bool intel_edp_psr_match_conditions(struct intel_dp *intel_dp)
+{
+	struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
+	struct drm_device *dev = dig_port->base.base.dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct drm_crtc *crtc = dig_port->base.base.crtc;
+	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
+	struct drm_i915_gem_object *obj = to_intel_framebuffer(crtc->fb)->obj;
+	struct intel_encoder *intel_encoder = &dp_to_dig_port(intel_dp)->base;
+
+	if (!IS_HASWELL(dev)) {
+		DRM_DEBUG_KMS("PSR not supported on this platform\n");
+		dev_priv->no_psr_reason = PSR_NO_SOURCE;
+		return false;
+	}
+
+	if ((intel_encoder->type != INTEL_OUTPUT_EDP) ||
+	    (dig_port->port != PORT_A)) {
+		DRM_DEBUG_KMS("HSW ties PSR to DDI A (eDP)\n");
+		dev_priv->no_psr_reason = PSR_HSW_NOT_DDIA;
+		return false;
+	}
+
+	if (!is_edp_psr(intel_dp)) {
+		DRM_DEBUG_KMS("PSR not supported by this panel\n");
+		dev_priv->no_psr_reason = PSR_NO_SINK;
+		return false;
+	}
+
+	if (!intel_crtc->active || !crtc->fb || !crtc->mode.clock) {
+		DRM_DEBUG_KMS("crtc not active for PSR\n");
+		dev_priv->no_psr_reason = PSR_CRTC_NOT_ACTIVE;
+		return false;
+	}
+
+	if (obj->tiling_mode != I915_TILING_X ||
+	    obj->fence_reg == I915_FENCE_REG_NONE) {
+		DRM_DEBUG_KMS("PSR condition failed: fb not tiled or fenced\n");
+		dev_priv->no_psr_reason = PSR_NOT_TILED;
+		return false;
+	}
+
+	if (I915_READ(SPRCTL(intel_crtc->pipe)) & SPRITE_ENABLE) {
+		DRM_DEBUG_KMS("PSR condition failed: Sprite is Enabled\n");
+		dev_priv->no_psr_reason = PSR_SPRITE_ENABLED;
+		return false;
+	}
+
+	if (I915_READ(HSW_STEREO_3D_CTL(intel_crtc->config.cpu_transcoder)) &
+	    S3D_ENABLE) {
+		DRM_DEBUG_KMS("PSR condition failed: Stereo 3D is Enabled\n");
+		dev_priv->no_psr_reason = PSR_S3D_ENABLED;
+		return false;
+	}
+
+	if (crtc->mode.flags & DRM_MODE_FLAG_INTERLACE) {
+		DRM_DEBUG_KMS("PSR condition failed: Interlaced is Enabled\n");
+		dev_priv->no_psr_reason = PSR_INTERLACED_ENABLED;
+		return false;
+	}
+
+	return true;
+}
+
 void intel_edp_psr_enable(struct intel_dp *intel_dp)
 {
 	struct drm_device *dev = intel_dp_to_dev(intel_dp);
 
-	if (!is_edp_psr(intel_dp) || intel_edp_is_psr_enabled(dev))
+	if (!intel_edp_psr_match_conditions(intel_dp) ||
+	    intel_edp_is_psr_enabled(dev))
 		return;
 
 	/* Setup PSR once */