drm/i915/dsi: Fix off by one in BXT_MIPI_TRANS_VTOTAL

BXT_MIPI_TRANS_VTOTAL must be programmed with vtotal-1
instead of vtotal. Make it so.

Cc: stable@vger.kernel.org
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250314150136.22564-1-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
(cherry picked from commit 7b3685c)
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>

Author: vsyrjala

drivers/gpu/drm/i915/display/vlv_dsi.c

@@ -1056,7 +1056,7 @@ static void bxt_dsi_get_pipe_config(struct intel_encoder *encoder,
 				              BXT_MIPI_TRANS_VACTIVE(port));
 	adjusted_mode->crtc_vtotal =
 				intel_de_read(display,
-				              BXT_MIPI_TRANS_VTOTAL(port));
+				              BXT_MIPI_TRANS_VTOTAL(port)) + 1;
 
 	hactive = adjusted_mode->crtc_hdisplay;
 	hfp = intel_de_read(display, MIPI_HFP_COUNT(display, port));
@@ -1260,7 +1260,7 @@ static void set_dsi_timings(struct intel_encoder *encoder,
 			intel_de_write(display, BXT_MIPI_TRANS_VACTIVE(port),
 				       adjusted_mode->crtc_vdisplay);
 			intel_de_write(display, BXT_MIPI_TRANS_VTOTAL(port),
-				       adjusted_mode->crtc_vtotal);
+				       adjusted_mode->crtc_vtotal - 1);
 		}
 
 		intel_de_write(display, MIPI_HACTIVE_AREA_COUNT(display, port),