drm/i915: report Gen5+ CPU and PCH FIFO underruns

In this commit we enable both CPU and PCH FIFO underrun reporting and
start reporting them. We follow a few rules:
  - after we receive one of these errors, we mask the interrupt, so
    we won't get an "interrupt storm" and we also won't flood dmesg;
  - at each mode set we enable the interrupts again, so we'll see each
    message at most once per mode set;
  - in the specific places where we need to ignore the errors, we
    completely mask the interrupts.

The downside of this patch is that since we're completely disabling
(masking) the interrupts instead of just not printing error messages,
we will mask more than just what we want on IVB/HSW CPU interrupts
(due to GEN7_ERR_INT) and on CPT/PPT/LPT PCHs (due to SERR_INT). So
when we decide to mask PCH FIFO underruns for pipe A on CPT, we'll
also be masking PCH FIFO underruns for pipe B, because both are
reported by SERR_INT, which has to be either completely enabled or
completely disabled (in othe words, there's no way to disable/enable
specific bits of GEN7_ERR_INT and SERR_INT).

V2: Rename some functions and variables, downgrade messages to
DRM_DEBUG_DRIVER and rebase.
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_reg.h

@@ -640,7 +640,10 @@
 
 #define ERROR_GEN6	0x040a0
 #define GEN7_ERR_INT	0x44040
-#define   ERR_INT_MMIO_UNCLAIMED (1<<13)
+#define   ERR_INT_MMIO_UNCLAIMED	(1<<13)
+#define   ERR_INT_FIFO_UNDERRUN_C	(1<<6)
+#define   ERR_INT_FIFO_UNDERRUN_B	(1<<3)
+#define   ERR_INT_FIFO_UNDERRUN_A	(1<<0)
 
 #define FPGA_DBG		0x42300
 #define   FPGA_DBG_RM_NOCLAIM	(1<<31)
@@ -3622,7 +3625,7 @@
 #define DE_PIPEA_FIFO_UNDERRUN  (1 << 0)
 
 /* More Ivybridge lolz */
-#define DE_ERR_DEBUG_IVB		(1<<30)
+#define DE_ERR_INT_IVB			(1<<30)
 #define DE_GSE_IVB			(1<<29)
 #define DE_PCH_EVENT_IVB		(1<<28)
 #define DE_DP_A_HOTPLUG_IVB		(1<<27)
@@ -3781,6 +3784,7 @@
 				 SDE_PORTC_HOTPLUG_CPT |	\
 				 SDE_PORTB_HOTPLUG_CPT)
 #define SDE_GMBUS_CPT		(1 << 17)
+#define SDE_ERROR_CPT		(1 << 16)
 #define SDE_AUDIO_CP_REQ_C_CPT	(1 << 10)
 #define SDE_AUDIO_CP_CHG_C_CPT	(1 << 9)
 #define SDE_FDI_RXC_CPT		(1 << 8)
@@ -3805,6 +3809,11 @@
 #define SDEIIR  0xc4008
 #define SDEIER  0xc400c
 
+#define SERR_INT			0xc4040
+#define  SERR_INT_TRANS_C_FIFO_UNDERRUN	(1<<6)
+#define  SERR_INT_TRANS_B_FIFO_UNDERRUN	(1<<3)
+#define  SERR_INT_TRANS_A_FIFO_UNDERRUN	(1<<0)
+
 /* digital port hotplug */
 #define PCH_PORT_HOTPLUG        0xc4030		/* SHOTPLUG_CTL */
 #define PORTD_HOTPLUG_ENABLE            (1 << 20)

drivers/gpu/drm/i915/intel_display.c

@@ -3346,6 +3346,10 @@ static void ironlake_crtc_enable(struct drm_crtc *crtc)
 		return;
 
 	intel_crtc->active = true;
+
+	intel_set_cpu_fifo_underrun_reporting(dev, pipe, true);
+	intel_set_pch_fifo_underrun_reporting(dev, pipe, true);
+
 	intel_update_watermarks(dev);
 
 	if (intel_pipe_has_type(crtc, INTEL_OUTPUT_LVDS)) {
@@ -3437,6 +3441,11 @@ static void haswell_crtc_enable(struct drm_crtc *crtc)
 		return;
 
 	intel_crtc->active = true;
+
+	intel_set_cpu_fifo_underrun_reporting(dev, pipe, true);
+	if (intel_crtc->config.has_pch_encoder)
+		intel_set_pch_fifo_underrun_reporting(dev, TRANSCODER_A, true);
+
 	intel_update_watermarks(dev);
 
 	if (intel_crtc->config.has_pch_encoder)
@@ -3523,6 +3532,7 @@ static void ironlake_crtc_disable(struct drm_crtc *crtc)
 	if (dev_priv->cfb_plane == plane)
 		intel_disable_fbc(dev);
 
+	intel_set_pch_fifo_underrun_reporting(dev, pipe, false);
 	intel_disable_pipe(dev_priv, pipe);
 
 	/* Disable PF */
@@ -3536,6 +3546,7 @@ static void ironlake_crtc_disable(struct drm_crtc *crtc)
 	ironlake_fdi_disable(crtc);
 
 	ironlake_disable_pch_transcoder(dev_priv, pipe);
+	intel_set_pch_fifo_underrun_reporting(dev, pipe, true);
 
 	if (HAS_PCH_CPT(dev)) {
 		/* disable TRANS_DP_CTL */
@@ -3602,6 +3613,8 @@ static void haswell_crtc_disable(struct drm_crtc *crtc)
 	if (dev_priv->cfb_plane == plane)
 		intel_disable_fbc(dev);
 
+	if (intel_crtc->config.has_pch_encoder)
+		intel_set_pch_fifo_underrun_reporting(dev, TRANSCODER_A, false);
 	intel_disable_pipe(dev_priv, pipe);
 
 	intel_ddi_disable_transcoder_func(dev_priv, cpu_transcoder);
@@ -3622,6 +3635,7 @@ static void haswell_crtc_disable(struct drm_crtc *crtc)
 
 	if (intel_crtc->config.has_pch_encoder) {
 		lpt_disable_pch_transcoder(dev_priv);
+		intel_set_pch_fifo_underrun_reporting(dev, TRANSCODER_A, true);
 		intel_ddi_fdi_disable(crtc);
 	}
 

drivers/gpu/drm/i915/intel_drv.h

@@ -265,6 +265,10 @@ struct intel_crtc {
 
 	/* reset counter value when the last flip was submitted */
 	unsigned int reset_counter;
+
+	/* Access to these should be protected by dev_priv->irq_lock. */
+	bool cpu_fifo_underrun_disabled;
+	bool pch_fifo_underrun_disabled;
 };
 
 struct intel_plane {
@@ -487,6 +491,7 @@ int intel_ddc_get_modes(struct drm_connector *c, struct i2c_adapter *adapter);
 extern void intel_attach_force_audio_property(struct drm_connector *connector);
 extern void intel_attach_broadcast_rgb_property(struct drm_connector *connector);
 
+extern bool intel_pipe_has_type(struct drm_crtc *crtc, int type);
 extern void intel_crt_init(struct drm_device *dev);
 extern void intel_hdmi_init(struct drm_device *dev,
 			    int hdmi_reg, enum port port);
@@ -743,5 +748,11 @@ intel_ddi_connector_get_hw_state(struct intel_connector *intel_connector);
 extern void intel_ddi_fdi_disable(struct drm_crtc *crtc);
 
 extern void intel_display_handle_reset(struct drm_device *dev);
+extern bool intel_set_cpu_fifo_underrun_reporting(struct drm_device *dev,
+						  enum pipe pipe,
+						  bool enable);
+extern bool intel_set_pch_fifo_underrun_reporting(struct drm_device *dev,
+						 enum transcoder pch_transcoder,
+						 bool enable);
 
 #endif /* __INTEL_DRV_H__ */