drm/fb: document drm_fb_helper_surface_size

	int x, y;

};

/**

 * struct drm_fb_helper_surface_size - describes fbdev size and scanout surface size

 * @fb_width: fbdev width

 * @fb_height: fbdev height

 * @surface_width: scanout buffer width

 * @surface_height: scanout buffer height

 * @surface_bpp: scanout buffer bpp

 * @surface_depth: scanout buffer depth

 *

 * Note that the scanout surface width/height may be larger than the fbdev

 * width/height.  In case of multiple displays, the scanout surface is sized

 * according to the largest width/height (so it is large enough for all CRTCs

 * to scanout).  But the fbdev width/height is sized to the minimum width/

 * height of all the displays.  This ensures that fbcon fits on the smallest

 * of the attached displays.

 *

 * So what is passed to drm_fb_helper_fill_var() should be fb_width/fb_height,

 * rather than the surface size.

 */

struct drm_fb_helper_surface_size {

	u32 fb_width;

	u32 fb_height;