On 4/28/2025 11:50 AM, Mitul Golani wrote:
Compute DC Balance parameters and tunable params based on
experiments.
--v2:
- Document tunable params. (Ankit)
Signed-off-by: Mitul Golani <[email protected]>
---
drivers/gpu/drm/i915/display/intel_vrr.c | 25 ++++++++++++++++++++++++
1 file changed, 25 insertions(+)
diff --git a/drivers/gpu/drm/i915/display/intel_vrr.c
b/drivers/gpu/drm/i915/display/intel_vrr.c
index 55923eadc3c1..bc99701be2b5 100644
--- a/drivers/gpu/drm/i915/display/intel_vrr.c
+++ b/drivers/gpu/drm/i915/display/intel_vrr.c
@@ -16,6 +16,13 @@
#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)
{
@@ -409,6 +416,24 @@ intel_vrr_compute_config(struct intel_crtc_state
*crtc_state,
(crtc_state->hw.adjusted_mode.crtc_vtotal -
crtc_state->hw.adjusted_mode.vsync_end);
}
+
+ if (HAS_VRR_DC_BALANCE(display) && crtc_state->vrr.dc_balance.enable) {
+ 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);
+ crtc_state->vrr.dc_balance.slope =
+ DIV_ROUND_UP(DCB_CORRECTION_AGGRESSIVENESS * 10,
+ crtc_state->vrr.dc_balance.guardband);
+ crtc_state->vrr.dc_balance.vblank_target =
+ DIV_ROUND_UP((crtc_state->vrr.vmax - crtc_state->vrr.vmin) *
DCB_BLANK_TARGET,
+ 100);
We can make the longer lines more readable with a bit of formatting by
breaking the line after multiplication or at comma:
crtc_state->vrr.dc_balance.guardband =
DIV_ROUND_UP(crtc_state->vrr.dc_balance.vmax *
DCB_CORRECTION_SENSITIVITY, 100);
crtc_state->vrr.dc_balance.slope =
DIV_ROUND_UP(DCB_CORRECTION_AGGRESSIVENESS * 10,
crtc_state->vrr.dc_balance.guardband);
crtc_state->vrr.dc_balance.vblank_target =
DIV_ROUND_UP((crtc_state->vrr.vmax -
crtc_state->vrr.vmin) *
DCB_BLANK_TARGET, 100);
Regards,
Ankit
+ }
}
void intel_vrr_compute_config_late(struct intel_crtc_state *crtc_state)
