[PATCH 24/35] drm/i915/vrr: Adjust Vtotal for MSA for fixed timings

[Ankit Nautiyal]

DP sink uses MSA timings for the fixed refresh rate mode.
For using VRR timing generator for fixed refresh rate mode, the HW prepares
the Vtotal for the MSA from the VMAX register. Since the MSA Vtotal is
one-based while Vmax is zero-based we need to take care of this while
setting Vtotal value for the fixed refresh rate mode.

Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal at intel.com>
---
 drivers/gpu/drm/i915/display/intel_vrr.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/display/intel_vrr.c b/drivers/gpu/drm/i915/display/intel_vrr.c
index f485c3e35d68..5a1b0d61c483 100644
--- a/drivers/gpu/drm/i915/display/intel_vrr.c
+++ b/drivers/gpu/drm/i915/display/intel_vrr.c
@@ -264,6 +264,18 @@ void intel_vrr_compute_vrr_timings(struct intel_crtc_state *crtc_state, int vmin
 	crtc_state->mode_flags |= I915_MODE_FLAG_VRR;
 }
 
+static
+int adjust_vtotal_for_msa(int vtotal)
+{
+	/*
+	 * DP sink uses MSA timings for the fixed refresh rate mode.
+	 * The HW prepares the Vtotal for the MSA from the VMAX register.
+	 * Since the MSA Vtotal is one-based while Vmax is zero-based we need to
+	 * take care of this while setting Vtotal value.
+	 */
+	return vtotal - 1;
+}
+
 static
 int intel_vrr_compute_vmin(struct intel_crtc_state *crtc_state)
 {
@@ -274,7 +286,7 @@ int intel_vrr_compute_vmin(struct intel_crtc_state *crtc_state)
 	 * 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;
+	return adjust_vtotal_for_msa(crtc_state->hw.adjusted_mode.crtc_vtotal);
 }
 
 static
-- 
2.45.2