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

drivers/video/modedb.c

+16 −8
Original line number Diff line number Diff line
@@ -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]) {
@@ -651,20 +651,28 @@ int fb_find_mode(struct fb_var_screeninfo *var, 
		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);

			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);

	    return 5;