drm/i915/vrr: Extract helpers to convert between guardband and pipeline_full values

I'd like to move towards a world where we can't more or less
pretend that the ICl/TGL VRR hardware works the same way as
ADL+. To that end extract some helpers to convert between
the guardband and pipeline_full representations.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250917203446.14374-2-ville.syrjala@linux.intel.com
Reviewed-by: Ankit Nautiyal <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 3eed37f271b02512fe228eb0837bddb1e03c93f7..5fee85b0bc99381a671d7be6c1e2a44bb46d10df 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_vrr.c
+++ b/drivers/gpu/drm/i915/display/intel_vrr.c
@@ -119,6 +119,20 @@ static int intel_vrr_vmin_flipline(const struct intel_crtc_state *crtc_state)
        return crtc_state->vrr.vmin + intel_vrr_flipline_offset(display);
 }
 
+static int intel_vrr_guardband_to_pipeline_full(const struct intel_crtc_state *crtc_state,
+                                               int guardband)
+{
+       /* hardware imposes one extra scanline somewhere */
+       return guardband - crtc_state->framestart_delay - 1;
+}
+
+static int intel_vrr_pipeline_full_to_guardband(const struct intel_crtc_state *crtc_state,
+                                               int pipeline_full)
+{
+       /* hardware imposes one extra scanline somewhere */
+       return pipeline_full + crtc_state->framestart_delay + 1;
+}
+
 /*
  * Without VRR registers get latched at:
  *  vblank_start
@@ -142,8 +156,8 @@ static int intel_vrr_vblank_exit_length(const struct intel_crtc_state *crtc_stat
        if (DISPLAY_VER(display) >= 13)
                return crtc_state->vrr.guardband;
        else
-               /* hardware imposes one extra scanline somewhere */
-               return crtc_state->vrr.pipeline_full + crtc_state->framestart_delay + 1;
+               return intel_vrr_pipeline_full_to_guardband(crtc_state,
+                                                           crtc_state->vrr.pipeline_full);
 }
 
 int intel_vrr_vmin_vtotal(const struct intel_crtc_state *crtc_state)
@@ -417,18 +431,18 @@ void intel_vrr_compute_config_late(struct intel_crtc_state *crtc_state)
 {
        struct intel_display *display = to_intel_display(crtc_state);
        const struct drm_display_mode *adjusted_mode = &crtc_state->hw.adjusted_mode;
+       int guardband;
 
        if (!intel_vrr_possible(crtc_state))
                return;
 
+       guardband = crtc_state->vrr.vmin - adjusted_mode->crtc_vblank_start;
+
        if (DISPLAY_VER(display) >= 13) {
-               crtc_state->vrr.guardband =
-                       crtc_state->vrr.vmin - adjusted_mode->crtc_vblank_start;
+               crtc_state->vrr.guardband = guardband;
        } else {
-               /* hardware imposes one extra scanline somewhere */
                crtc_state->vrr.pipeline_full =
-                       min(255, crtc_state->vrr.vmin - adjusted_mode->crtc_vblank_start -
-                           crtc_state->framestart_delay - 1);
+                       min(255, intel_vrr_guardband_to_pipeline_full(crtc_state, guardband));
 
                /*
                 * vmin/vmax/flipline also need to be adjusted by