[PATCH 6/8] drm/i915/histogram: histogram delay counter doesnt reset

[Arun R Murthy <arun.r.murthy@intel.com>]

The delay counter for histogram does not reset and as a result the
histogram bin never gets updated. Workaround would be to use save and
restore histogram register.
Wa: 14014889975

Signed-off-by: Arun R Murthy <arun.r.murthy@intel.com>
---
 drivers/gpu/drm/i915/display/intel_histogram.c  | 17 +++++++++++++++++
 .../gpu/drm/i915/display/intel_histogram_regs.h |  1 +
 2 files changed, 18 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_histogram.c b/drivers/gpu/drm/i915/display/intel_histogram.c
index cba65f4260cd..fdcc64677e96 100644
--- a/drivers/gpu/drm/i915/display/intel_histogram.c
+++ b/drivers/gpu/drm/i915/display/intel_histogram.c
@@ -74,6 +74,11 @@ static void intel_histogram_handle_int_work(struct work_struct *work)
 	struct intel_display *display = to_intel_display(intel_crtc);
 	char *histogram_event[] = {"HISTOGRAM=1", NULL};
 
+	/* Wa: 14014889975 */
+	if (IS_DISPLAY_VER(display, 12, 13))
+		intel_de_rmw(display, DPST_CTL(intel_crtc->pipe),
+			     DPST_CTL_RESTORE, 0);
+
 	/*
 	 * TODO: PSR to be exited while reading the Histogram data
 	 * Set DPST_CTL Bin Reg function select to TC
@@ -94,6 +99,12 @@ static void intel_histogram_handle_int_work(struct work_struct *work)
 				"sending HISTOGRAM event failed\n");
 	}
 
+	/* Wa: 14014889975 */
+	if (IS_DISPLAY_VER(display, 12, 13))
+		/* Write the value read from DPST_CTL to DPST_CTL.Interrupt Delay Counter(bit 23:16) */
+		intel_de_write(display, DPST_CTL(intel_crtc->pipe), intel_de_read(display,
+			       DPST_CTL(intel_crtc->pipe)) | DPST_CTL_RESTORE);
+
 	/* Enable histogram interrupt */
 	intel_de_rmw(display, DPST_GUARD(intel_crtc->pipe), DPST_GUARD_HIST_INT_EN,
 		     DPST_GUARD_HIST_INT_EN);
@@ -240,6 +251,12 @@ int intel_histogram_set_iet_lut(struct intel_crtc *intel_crtc, u32 *data)
 		return -EINVAL;
 	}
 
+	/* Wa: 14014889975 */
+	if (IS_DISPLAY_VER(display, 12, 13))
+		/* Write the value read from DPST_CTL to DPST_CTL.Interrupt Delay Counter(bit 23:16) */
+		intel_de_write(display, DPST_CTL(intel_crtc->pipe), intel_de_read(display,
+			       DPST_CTL(intel_crtc->pipe)) | DPST_CTL_RESTORE);
+
 	/*
 	 * Set DPST_CTL Bin Reg function select to IE
 	 * Set DPST_CTL Bin Register Index to 0
diff --git a/drivers/gpu/drm/i915/display/intel_histogram_regs.h b/drivers/gpu/drm/i915/display/intel_histogram_regs.h
index 1252b4f339a6..e50b1448bd40 100644
--- a/drivers/gpu/drm/i915/display/intel_histogram_regs.h
+++ b/drivers/gpu/drm/i915/display/intel_histogram_regs.h
@@ -16,6 +16,7 @@
 #define  DPST_CTL_RESTORE				REG_BIT(28)
 #define  DPST_CTL_IE_MODI_TABLE_EN			REG_BIT(27)
 #define  DPST_CTL_HIST_MODE				REG_BIT(24)
+#define  DPST_CTL_GUARDBAND_INTERRUPT_DELAY_CNT		REG_GENMASK(23, 16)
 #define  DPST_CTL_ENHANCEMENT_MODE_MASK			REG_GENMASK(14, 13)
 #define  DPST_CTL_EN_MULTIPLICATIVE			REG_FIELD_PREP(DPST_CTL_ENHANCEMENT_MODE_MASK, 2)
 #define  DPST_CTL_IE_TABLE_VALUE_FORMAT			REG_BIT(15)
-- 
2.25.1