drm/i915/vrr: Use crtc_vtotal for vmin

To have fixed refresh rate with VRR timing generator the
guardband/pipeline full can't be programmed on the fly. So we need to
ensure that the values satisfy both the fixed and variable refresh
rates.

Since we compute these value based on vmin, lets set the vmin to
crtc_vtotal for both fixed and variable timings instead of using the
current refresh rate based approach. This way the guardband remains
sufficient for both cases.

v2: Avoid using vblank delay while computing vtotal, as this comes into
the picture later. (Ville)

Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250311093751.1329043-7-ankit.k.nautiyal@intel.com

diff --git a/drivers/gpu/drm/i915/display/intel_vrr.c b/drivers/gpu/drm/i915/display/intel_vrr.c
index 7320eb97991f6c41c2ade9c7e6ca4f4df56b9d44..e0573e28014bffda22d6978a8fdedbf9d70fe9b5 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_vrr.c
+++ b/drivers/gpu/drm/i915/display/intel_vrr.c
@@ -247,17 +247,16 @@ void intel_vrr_compute_vrr_timings(struct intel_crtc_state *crtc_state)
 }
 
 static
-int intel_vrr_compute_vmin(struct intel_connector *connector,
-                          const struct drm_display_mode *adjusted_mode)
+int intel_vrr_compute_vmin(struct intel_crtc_state *crtc_state)
 {
-       const struct drm_display_info *info = &connector->base.display_info;
-       int vmin;
-
-       vmin = DIV_ROUND_UP(adjusted_mode->crtc_clock * 1000,
-                           adjusted_mode->crtc_htotal * info->monitor_range.max_vfreq);
-       vmin = max_t(int, vmin, adjusted_mode->crtc_vtotal);
-
-       return vmin;
+       /*
+        * To make fixed rr and vrr work seamless the guardband/pipeline full
+        * should be set such that it satisfies both the fixed and variable
+        * timings.
+        * For this set the vmin as crtc_vtotal. With this we never need to
+        * change anything to do with the guardband.
+        */
+       return crtc_state->hw.adjusted_mode.crtc_vtotal;
 }
 
 static
@@ -304,7 +303,7 @@ intel_vrr_compute_config(struct intel_crtc_state *crtc_state,
        if (HAS_LRR(display))
                crtc_state->update_lrr = true;
 
-       vmin = intel_vrr_compute_vmin(connector, adjusted_mode);
+       vmin = intel_vrr_compute_vmin(crtc_state);
        vmax = intel_vrr_compute_vmax(connector, adjusted_mode);
 
        if (vmin >= vmax)