drm/mode: add the GTF algorithm in kernel space

Add the GTF 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/xf86gtf.c. What I have
done is to translate it by using integer calculation. This is to avoid
the float-point calculation in kernel space.
At the same tie I also refer to the function of fb_get_mode in
drivers/video/fbmon.c

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 820bc0977e5e..125994d8ac0b 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -739,4 +739,7 @@ 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);
+extern struct drm_display_mode *drm_gtf_mode(struct drm_device *dev,
+                                int hdisplay, int vdisplay, int vrefresh,
+                                bool interlaced, int margins);
 #endif /* __DRM_CRTC_H__ */