[PATCH v8 07/18] drm/i915/vrr: Add compute config for DC Balance params

[Mitul Golani <mitulkumar.ajitkumar.golani@intel.com>]

Compute DC Balance parameters and tunable params based on
experiments.

--v2:
- Document tunable params. (Ankit)

--v3:
- Add line spaces to compute config. (Ankit)
- Remove redundancy checks.

--v4:
- Separate out conpute config to separate function.
- As all the valuse are being computed in scanlines, and slope
is still in usec, convert and store it to scanlines.

Signed-off-by: Mitul Golani <mitulkumar.ajitkumar.golani@intel.com>
---
 drivers/gpu/drm/i915/display/intel_vrr.c | 38 ++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_vrr.c b/drivers/gpu/drm/i915/display/intel_vrr.c
index 650077eb280f..7cb484dd96df 100644
--- a/drivers/gpu/drm/i915/display/intel_vrr.c
+++ b/drivers/gpu/drm/i915/display/intel_vrr.c
@@ -6,6 +6,7 @@
 
 #include <drm/drm_print.h>
 
+#include "intel_crtc.h"
 #include "intel_de.h"
 #include "intel_display_regs.h"
 #include "intel_display_types.h"
@@ -20,6 +21,14 @@
 #define FIXED_POINT_PRECISION		100
 #define CMRR_PRECISION_TOLERANCE	10
 
+/*
+ * Tunable parameters for DC Balance correction.
+ * These are captured based on experimentations.
+ */
+#define DCB_CORRECTION_SENSITIVITY	30
+#define DCB_CORRECTION_AGGRESSIVENESS	1000
+#define DCB_BLANK_TARGET		50
+
 bool intel_vrr_is_capable(struct intel_connector *connector)
 {
 	struct intel_display *display = to_intel_display(connector);
@@ -342,6 +351,33 @@ int intel_vrr_compute_vmax(struct intel_connector *connector,
 	return vmax;
 }
 
+static void
+intel_vrr_dc_balance_compute_config(struct intel_crtc_state *crtc_state)
+{
+	int val;
+	struct drm_display_mode *adjusted_mode = &crtc_state->hw.adjusted_mode;
+
+	if (!crtc_state->vrr.dc_balance.enable)
+		return;
+
+	crtc_state->vrr.dc_balance.vmax = crtc_state->vrr.vmax;
+	crtc_state->vrr.dc_balance.vmin = crtc_state->vrr.vmin;
+	crtc_state->vrr.dc_balance.max_increase =
+		crtc_state->vrr.vmax - crtc_state->vrr.vmin;
+	crtc_state->vrr.dc_balance.max_decrease =
+		crtc_state->vrr.vmax - crtc_state->vrr.vmin;
+	crtc_state->vrr.dc_balance.guardband =
+		DIV_ROUND_UP(crtc_state->vrr.dc_balance.vmax *
+			     DCB_CORRECTION_SENSITIVITY, 100);
+	val = DIV_ROUND_UP(DCB_CORRECTION_AGGRESSIVENESS * 10,
+			   crtc_state->vrr.dc_balance.guardband);
+	crtc_state->vrr.dc_balance.slope =
+		intel_usecs_to_scanlines(adjusted_mode, val);
+	crtc_state->vrr.dc_balance.vblank_target =
+		DIV_ROUND_UP((crtc_state->vrr.vmax - crtc_state->vrr.vmin) *
+			     DCB_BLANK_TARGET, 100);
+}
+
 void
 intel_vrr_compute_config(struct intel_crtc_state *crtc_state,
 			 struct drm_connector_state *conn_state)
@@ -399,6 +435,8 @@ intel_vrr_compute_config(struct intel_crtc_state *crtc_state,
 			(crtc_state->hw.adjusted_mode.crtc_vtotal -
 			 crtc_state->hw.adjusted_mode.crtc_vsync_end);
 	}
+
+	intel_vrr_dc_balance_compute_config(crtc_state);
 }
 
 static int
-- 
2.48.1