Commit 6b745b6f authored by Michal Januszewski's avatar Michal Januszewski Committed by Linus Torvalds

fbdev: make the best-fit section of fb_find_mode return the closest matching mode

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 all valid video modes are considered when
looking for a best-fit mode, while still preferring modes with a higher
resolution.
Signed-off-by: default avatarMichal Januszewski <spock@gentoo.org>
Cc: Krzysztof Helt <krzysztof.h1@poczta.fm>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 169b6a7a
......@@ -522,7 +522,7 @@ int fb_find_mode(struct fb_var_screeninfo *var,
int res_specified = 0, bpp_specified = 0, refresh_specified = 0;
unsigned int xres = 0, yres = 0, bpp = default_bpp, refresh = 0;
int yres_specified = 0, cvt = 0, rb = 0, interlace = 0, margins = 0;
u32 best, diff;
u32 best, diff, tdiff;
for (i = namelen-1; i >= 0; i--) {
switch (name[i]) {
......@@ -651,19 +651,27 @@ done:
return (refresh_specified) ? 2 : 1;
}
diff = xres + yres;
diff = 2 * (xres + yres);
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;
}
tdiff = abs(db[i].xres - xres) +
abs(db[i].yres - yres);
/*
* Penalize modes with resolutions smaller
* than requested.
*/
if (xres > db[i].xres || yres > db[i].yres)
tdiff += xres + yres;
if (diff > tdiff) {
diff = tdiff;
best = i;
}
}
}
}
if (best != -1) {
fb_try_mode(var, info, &db[best], bpp);
......
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