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>

1 files changed, 11 insertions, 2 deletions

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index fb1a4fa68d55..32f970d2fd51 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/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)