drm/mode: add the CVT algorithm in kernel space

Add the CVT algorithm in kernel space. And this function can be called to
generate the required modeline.

I copied it from the file of xserver/hw/xfree86/modes/xf86cvt.c. What I have
done is to translate it by using integer calculation. This is to avoid
the float-point calculation in kernel space.

[airlied:- cleaned up some bits]
Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Signed-off-by: Dave Airlie <airlied@linux.ie>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index 7300fb866767..820bc0977e5e 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -736,4 +736,7 @@ extern int drm_mode_gamma_get_ioctl(struct drm_device *dev,
 extern int drm_mode_gamma_set_ioctl(struct drm_device *dev,
                                     void *data, struct drm_file *file_priv);
 extern bool drm_detect_hdmi_monitor(struct edid *edid);
+extern struct drm_display_mode *drm_cvt_mode(struct drm_device *dev,
+                                int hdisplay, int vdisplay, int vrefresh,
+                                bool reduced, bool interlaced);
 #endif /* __DRM_CRTC_H__ */