Re: [PATCH v11 08/18] drm/i915/vrr: Add function to check if DC Balance Possible

[Nautiyal, Ankit K]

On 12/23/2025 4:15 PM, Mitul Golani wrote:

Add function to check if DC Balance possibile on
requested PIPE and also validate along with DISPLAY_VER
check.

s/possibile/possible

Perhaps it can be rephrased as:

Add a function that checks if DC Balance enabling is possible on the
requested PIPE. Apart from the DISPLAY_VER check, account for current
firmware limitations, which only allow DC Balance on PIPE A and PIPE B.

With the above changes:

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

Signed-off-by: Mitul Golani <mitulkumar.ajitkumar.gol...@intel.com>
---
  drivers/gpu/drm/i915/display/intel_vrr.c | 19 +++++++++++++++++--
  1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_vrr.c 
b/drivers/gpu/drm/i915/display/intel_vrr.c
index 952e3c31bacc..dbfe56e8973d 100644
--- a/drivers/gpu/drm/i915/display/intel_vrr.c
+++ b/drivers/gpu/drm/i915/display/intel_vrr.c
@@ -351,13 +351,28 @@ int intel_vrr_compute_vmax(struct intel_connector 
*connector,
        return vmax;
  }

+static bool intel_vrr_dc_balance_possible(const struct intel_crtc_state *crtc_state)

+{
+       struct intel_display *display = to_intel_display(crtc_state);
+       struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
+       enum pipe pipe = crtc->pipe;
+
+       /*
+        * FIXME: Currently Firmware supports DC Balancing on PIPE A
+        * and PIPE B. Account those limitation while computing DC
+        * Balance parameters.
+        */
+       return (HAS_VRR_DC_BALANCE(display) &&
+               ((pipe == PIPE_A) || (pipe == PIPE_B)));
+}
+
  static void
  intel_vrr_dc_balance_compute_config(struct intel_crtc_state *crtc_state)
  {
        int guardband_usec, adjustment_usec;
        struct drm_display_mode *adjusted_mode = &crtc_state->hw.adjusted_mode;

- if (!HAS_VRR_DC_BALANCE(display) || !crtc_state->vrr.enable)

+       if (!intel_vrr_dc_balance_possible(crtc_state) || 
!crtc_state->vrr.enable)
                return;

crtc_state->vrr.dc_balance.vmax = crtc_state->vrr.vmax;

@@ -839,7 +854,7 @@ void intel_vrr_get_dc_balance_config(struct 
intel_crtc_state *crtc_state)
        struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
        enum pipe pipe = crtc->pipe;

- if (!HAS_VRR_DC_BALANCE(display))

+       if (!intel_vrr_dc_balance_possible(crtc_state))
                return;

reg_val = intel_de_read(display, PIPEDMC_DCB_VMIN(pipe));