Re: [PATCH v9 08/17] drm/i915/vrr: Add function to reset DC balance accumulated params

[Nautiyal, Ankit K]

On 11/27/2025 2:46 PM, Mitul Golani wrote:

Add function which resets all accumulated DC Balance parameters
whenever adaptive mode of VRR goes off. This helps to give a
fresh start when VRR is re-enabled.

--v2:
- Typo, change crtc_state to old_crtc_state. (Ankit)

Signed-off-by: Mitul Golani <mitulkumar.ajitkumar.gol...@intel.com>

Reviewed-by: Ankit Nautiyal <ankit.k.nauti...@intel.com>

---
  drivers/gpu/drm/i915/display/intel_display.c |  1 +
  drivers/gpu/drm/i915/display/intel_vrr.c     | 13 +++++++++++++
  drivers/gpu/drm/i915/display/intel_vrr.h     |  3 +++
  3 files changed, 17 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_display.c 
b/drivers/gpu/drm/i915/display/intel_display.c
index db4f84cb8762..d41ab965c013 100644
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -1158,6 +1158,7 @@ static void intel_pre_plane_update(struct 
intel_atomic_state *state,

if (intel_crtc_vrr_disabling(state, crtc)) {

                intel_vrr_disable(old_crtc_state);
+               intel_vrr_dcb_reset(old_crtc_state, crtc);
                intel_crtc_update_active_timings(old_crtc_state, false);
        }

diff --git a/drivers/gpu/drm/i915/display/intel_vrr.c b/drivers/gpu/drm/i915/display/intel_vrr.c

index 45e632e8a981..ff65c1167e1b 100644
--- a/drivers/gpu/drm/i915/display/intel_vrr.c
+++ b/drivers/gpu/drm/i915/display/intel_vrr.c
@@ -632,6 +632,19 @@ void intel_vrr_set_transcoder_timings(const struct 
intel_crtc_state *crtc_state)
                               EMP_AS_SDP_DB_TL(crtc_state->vrr.vsync_start));
  }

+void

+intel_vrr_dcb_reset(const struct intel_crtc_state *old_crtc_state,
+                   struct intel_crtc *crtc)
+{
+       struct intel_display *display = to_intel_display(old_crtc_state);
+       enum pipe pipe = crtc->pipe;
+
+       if (!old_crtc_state->vrr.dc_balance.enable)
+               return;
+
+       intel_de_write(display, PIPEDMC_DCB_BALANCE_RESET(pipe), 0);
+}
+
  void intel_vrr_send_push(struct intel_dsb *dsb,
                         const struct intel_crtc_state *crtc_state)
  {
diff --git a/drivers/gpu/drm/i915/display/intel_vrr.h 
b/drivers/gpu/drm/i915/display/intel_vrr.h
index 66fb9ad846f2..d40ed5504180 100644
--- a/drivers/gpu/drm/i915/display/intel_vrr.h
+++ b/drivers/gpu/drm/i915/display/intel_vrr.h
@@ -11,6 +11,7 @@
  struct drm_connector_state;
  struct intel_atomic_state;
  struct intel_connector;
+struct intel_crtc;
  struct intel_crtc_state;
  struct intel_dsb;
  struct intel_display;
@@ -39,6 +40,8 @@ bool intel_vrr_is_fixed_rr(const struct intel_crtc_state 
*crtc_state);
  void intel_vrr_transcoder_enable(const struct intel_crtc_state *crtc_state);
  void intel_vrr_transcoder_disable(const struct intel_crtc_state *crtc_state);
  void intel_vrr_set_fixed_rr_timings(const struct intel_crtc_state 
*crtc_state);
+void intel_vrr_dcb_reset(const struct intel_crtc_state *old_crtc_state,
+                        struct intel_crtc *crtc);
  bool intel_vrr_always_use_vrr_tg(struct intel_display *display);
  int intel_vrr_safe_window_start(const struct intel_crtc_state *crtc_state);
  int intel_vrr_vmin_safe_window_end(const struct intel_crtc_state *crtc_state);