Commit 003cfc0c authored by Antonino A. Daplas's avatar Antonino A. Daplas Committed by Linus Torvalds

[PATCH] fbdev: Add helper to get an appropriate initial mode

Add new helper, fb_find_best_display(), which will search the modelist for the
best mode for the attached display.  This requires an EDID block that is
converted to struct fb_monspecs and a private modelist.  The search will be
done in this manner:

- if 1st detailed timing is preferred, use that
- else if dimensions of the display are known, use that to estimate xres and
- else if modelist has detailed timings, use the first detailed timing
- else, use the very first entry from the modelist
Signed-off-by: default avatarAntonino Daplas <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent 14c8102f
......@@ -944,6 +944,66 @@ void fb_videomode_to_modelist(struct fb_videomode *modedb, int num,
struct fb_videomode *fb_find_best_display(struct fb_monspecs *specs,
struct list_head *head)
struct list_head *pos;
struct fb_modelist *modelist;
struct fb_videomode *m, *m1 = NULL, *md = NULL, *best = NULL;
int first = 0;
if (!head->prev || !head->next || list_empty(head))
goto finished;
/* get the first detailed mode and the very first mode */
list_for_each(pos, head) {
modelist = list_entry(pos, struct fb_modelist, list);
m = &modelist->mode;
if (!first) {
m1 = m;
first = 1;
if (m->flag & FB_MODE_IS_FIRST) {
md = m;
/* first detailed timing is preferred */
if (specs->misc & FB_MISC_1ST_DETAIL) {
best = md;
goto finished;
/* find best mode based on display width and height */
if (specs->max_x && specs->max_y) {
struct fb_var_screeninfo var;
memset(&var, 0, sizeof(struct fb_var_screeninfo));
var.xres = (specs->max_x * 7200)/254;
var.yres = (specs->max_y * 7200)/254;
m = fb_find_best_mode(&var, head);
if (m) {
best = m;
goto finished;
/* use first detailed mode */
if (md) {
best = md;
goto finished;
/* last resort, use the very first mode */
best = m1;
return best;
......@@ -902,6 +902,8 @@ extern struct fb_videomode *fb_find_nearest_mode(struct fb_videomode *mode,
extern void fb_destroy_modelist(struct list_head *head);
extern void fb_videomode_to_modelist(struct fb_videomode *modedb, int num,
struct list_head *head);
extern struct fb_videomode *fb_find_best_display(struct fb_monspecs *specs,
struct list_head *head);
/* drivers/video/fbcmap.c */
extern int fb_alloc_cmap(struct fb_cmap *cmap, int len, int transp);
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