[PATCH] fbdev: make the best-fit section of fb_find_mode returnthe closest matching mode

From: Michal Januszewski
Date: Sun Jan 27 2008 - 06:32:04 EST


From: Michal Januszewski <spock@xxxxxxxxxx>

Currently, if a perfect match in terms of resolution is not found,
fb_find_mode() only looks for a best-fit mode among modes with a
higher resolution than the one requested. Thus, if the user
requests a resolution higher than the largest supported one, they
are dropped to the default mode (usually a low resolution one).

Change this behaviour so that the true closest match in terms
of the city-block metric is returned.

Signed-off-by: Michal Januszewski <spock@xxxxxxxxxx>
---
diff --git a/drivers/video/modedb.c b/drivers/video/modedb.c
index 08d0725..bc29ef3 100644
--- a/drivers/video/modedb.c
+++ b/drivers/video/modedb.c
@@ -655,15 +655,15 @@ done:
best = -1;
DPRINTK("Trying best-fit modes\n");
for (i = 0; i < dbsize; i++) {
- if (xres <= db[i].xres && yres <= db[i].yres) {
DPRINTK("Trying %ix%i\n", db[i].xres, db[i].yres);
if (!fb_try_mode(var, info, &db[i], bpp)) {
- if (diff > (db[i].xres - xres) + (db[i].yres - yres)) {
- diff = (db[i].xres - xres) + (db[i].yres - yres);
- best = i;
- }
+ if (diff > abs(db[i].xres - xres) +
+ abs(db[i].yres - yres)) {
+ diff = abs(db[i].xres - xres) +
+ abs(db[i].yres - yres);
+ best = i;
+ }
}
- }
}
if (best != -1) {
fb_try_mode(var, info, &db[best], bpp);

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