drm: Fix vblank timestamping constants for interlaced modes

[karo-tx-linux.git] / drivers / gpu / drm / drm_irq.c

diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
index 91e8b4c55ea0d47f88e2e8b45c655de80ea5cbf7..55239d285f251bdcefc364d9b10b4694e8fa6886 100644 (file)
--- a/drivers/gpu/drm/drm_irq.c
+++ b/drivers/gpu/drm/drm_irq.c
@@ -453,12 +453,6 @@ void drm_calc_timestamping_constants(struct drm_crtc *crtc,
        int linedur_ns = 0, pixeldur_ns = 0, framedur_ns = 0;
        int dotclock = mode->crtc_clock;
 
-       /* Fields of interlaced scanout modes are only half a frame duration.
-        * Double the dotclock to get half the frame-/line-/pixelduration.
-        */
-       if (mode->flags & DRM_MODE_FLAG_INTERLACE)
-               dotclock *= 2;
-
        /* Valid dotclock? */
        if (dotclock > 0) {
                int frame_size = mode->crtc_htotal * mode->crtc_vtotal;
@@ -471,6 +465,12 @@ void drm_calc_timestamping_constants(struct drm_crtc *crtc,
                pixeldur_ns = 1000000 / dotclock;
                linedur_ns  = div_u64((u64) mode->crtc_htotal * 1000000, dotclock);
                framedur_ns = div_u64((u64) frame_size * 1000000, dotclock);
+
+               /*
+                * Fields of interlaced scanout modes are only half a frame duration.
+                */
+               if (mode->flags & DRM_MODE_FLAG_INTERLACE)
+                       framedur_ns /= 2;
        } else
                DRM_ERROR("crtc %d: Can't calculate constants, dotclock = 0!\n",
                          crtc->base.id);