drm/kms: try to find the std mode in DMT table

When we need to add the standard timing mode, we will firstly check whether it
can be found in DMT table by comparing the hdisplay/vdisplay/vfresh_rate.
If it can't be found, then we will use the cvt/gtf to add the required mode.
If it can be found, it will be returned.

At the same time the function of drm_mode_vrefresh is also fixed. It will
return the result of actual refresh_rate plus 0.5.
For example:
When the calculated value is 84.9, then the fresh_rate is 85.
When the calculated value is 70.02, then the fresh_rate is 70.

Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 6 insertions, 5 deletions

diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c
index ab6e70eadc58..49404ce1666e 100644
--- a/drivers/gpu/drm/drm_modes.c
+++ b/drivers/gpu/drm/drm_modes.c
@@ -566,7 +566,9 @@ EXPORT_SYMBOL(drm_mode_height);
  * FIXME: why is this needed?  shouldn't vrefresh be set already?
  *
  * RETURNS:
- * Vertical refresh rate of @mode x 1000. For precision reasons.
+ * Vertical refresh rate. It will be the result of actual value plus 0.5.
+ * If it is 70.288, it will return 70Hz.
+ * If it is 59.6, it will return 60Hz.
  */
 int drm_mode_vrefresh(struct drm_display_mode *mode)
 {
@@ -576,14 +578,13 @@ int drm_mode_vrefresh(struct drm_display_mode *mode)
         if (mode->vrefresh > 0)
                 refresh = mode->vrefresh;
         else if (mode->htotal > 0 && mode->vtotal > 0) {
+                int vtotal;
+                vtotal = mode->vtotal;
                 /* work out vrefresh the value will be x1000 */
                 calc_val = (mode->clock * 1000);
-
                 calc_val /= mode->htotal;
-                calc_val *= 1000;
-                calc_val /= mode->vtotal;
+                refresh = (calc_val + vtotal / 2) / vtotal;
 
-                refresh = calc_val;
                 if (mode->flags & DRM_MODE_FLAG_INTERLACE)
                         refresh *= 2;
                 if (mode->flags & DRM_MODE_FLAG_DBLSCAN)