drm/modes: Fix CVT-R modeline generation

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=16651

Signed-off-by: Adam Jackson <ajax@redhat.com>
Tested-by: Adam Serbinski <adam@serbinksi.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/drm_modes.c

@@ -251,7 +251,10 @@ struct drm_display_mode *drm_cvt_mode(struct drm_device *dev, int hdisplay,
 		drm_mode->htotal = drm_mode->hdisplay + CVT_RB_H_BLANK;
 		/* Fill in HSync values */
 		drm_mode->hsync_end = drm_mode->hdisplay + CVT_RB_H_BLANK / 2;
-		drm_mode->hsync_start = drm_mode->hsync_end = CVT_RB_H_SYNC;
+		drm_mode->hsync_start = drm_mode->hsync_end - CVT_RB_H_SYNC;
+		/* Fill in VSync values */
+		drm_mode->vsync_start = drm_mode->vdisplay + CVT_RB_VFPORCH;
+		drm_mode->vsync_end = drm_mode->vsync_start + vsync;
 	}
 	/* 15/13. Find pixel clock frequency (kHz for xf86) */
 	drm_mode->clock = drm_mode->htotal * HV_FACTOR * 1000 / hperiod;