int fb_find_mode()

in fbdev/core/modedb.c [617:839]

• 187 lines of code
• 73 McCabe index (conditional complexity)

int fb_find_mode(struct fb_var_screeninfo *var,
		 struct fb_info *info, const char *mode_option,
		 const struct fb_videomode *db, unsigned int dbsize,
		 const struct fb_videomode *default_mode,
		 unsigned int default_bpp)
{
	int i;

	/* Set up defaults */
	if (!db) {
		db = modedb;
		dbsize = ARRAY_SIZE(modedb);
	}

	if (!default_mode)
		default_mode = &db[0];

	if (!default_bpp)
		default_bpp = 8;

	/* Did the user specify a video mode? */
	if (!mode_option)
		mode_option = fb_mode_option;
	if (mode_option) {
		const char *name = mode_option;
		unsigned int namelen = strlen(name);
		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;
		int interlace_specified = 0, interlace = 0;
		int margins = 0;
		u32 best, diff, tdiff;

		for (i = namelen-1; i >= 0; i--) {
			switch (name[i]) {
			case '@':
				namelen = i;
				if (!refresh_specified && !bpp_specified &&
				    !yres_specified) {
					refresh = simple_strtol(&name[i+1], NULL,
								10);
					refresh_specified = 1;
					if (cvt || rb)
						cvt = 0;
				} else
					goto done;
				break;
			case '-':
				namelen = i;
				if (!bpp_specified && !yres_specified) {
					bpp = simple_strtol(&name[i+1], NULL,
							    10);
					bpp_specified = 1;
					if (cvt || rb)
						cvt = 0;
				} else
					goto done;
				break;
			case 'x':
				if (!yres_specified) {
					yres = simple_strtol(&name[i+1], NULL,
							     10);
					yres_specified = 1;
				} else
					goto done;
				break;
			case '0' ... '9':
				break;
			case 'M':
				if (!yres_specified)
					cvt = 1;
				break;
			case 'R':
				if (!cvt)
					rb = 1;
				break;
			case 'm':
				if (!cvt)
					margins = 1;
				break;
			case 'p':
				if (!cvt) {
					interlace = 0;
					interlace_specified = 1;
				}
				break;
			case 'i':
				if (!cvt) {
					interlace = 1;
					interlace_specified = 1;
				}
				break;
			default:
				goto done;
			}
		}
		if (i < 0 && yres_specified) {
			xres = simple_strtol(name, NULL, 10);
			res_specified = 1;
		}
done:
		if (cvt) {
			struct fb_videomode cvt_mode;
			int ret;

			DPRINTK("CVT mode %dx%d@%dHz%s%s%s\n", xres, yres,
				(refresh) ? refresh : 60,
				(rb) ? " reduced blanking" : "",
				(margins) ? " with margins" : "",
				(interlace) ? " interlaced" : "");

			memset(&cvt_mode, 0, sizeof(cvt_mode));
			cvt_mode.xres = xres;
			cvt_mode.yres = yres;
			cvt_mode.refresh = (refresh) ? refresh : 60;

			if (interlace)
				cvt_mode.vmode |= FB_VMODE_INTERLACED;
			else
				cvt_mode.vmode &= ~FB_VMODE_INTERLACED;

			ret = fb_find_mode_cvt(&cvt_mode, margins, rb);

			if (!ret && !fb_try_mode(var, info, &cvt_mode, bpp)) {
				DPRINTK("modedb CVT: CVT mode ok\n");
				return 1;
			}

			DPRINTK("CVT mode invalid, getting mode from database\n");
		}

		DPRINTK("Trying specified video mode%s %ix%i\n",
			refresh_specified ? "" : " (ignoring refresh rate)",
			xres, yres);

		if (!refresh_specified) {
			/*
			 * If the caller has provided a custom mode database and
			 * a valid monspecs structure, we look for the mode with
			 * the highest refresh rate.  Otherwise we play it safe
			 * it and try to find a mode with a refresh rate closest
			 * to the standard 60 Hz.
			 */
			if (db != modedb &&
			    info->monspecs.vfmin && info->monspecs.vfmax &&
			    info->monspecs.hfmin && info->monspecs.hfmax &&
			    info->monspecs.dclkmax) {
				refresh = 1000;
			} else {
				refresh = 60;
			}
		}

		diff = -1;
		best = -1;
		for (i = 0; i < dbsize; i++) {
			if ((name_matches(db[i], name, namelen) ||
			     (res_specified && res_matches(db[i], xres, yres))) &&
			    !fb_try_mode(var, info, &db[i], bpp)) {
				const int db_interlace = (db[i].vmode &
					FB_VMODE_INTERLACED ? 1 : 0);
				int score = abs(db[i].refresh - refresh);

				if (interlace_specified)
					score += abs(db_interlace - interlace);

				if (!interlace_specified ||
				    db_interlace == interlace)
					if (refresh_specified &&
					    db[i].refresh == refresh)
						return 1;

				if (score < diff) {
					diff = score;
					best = i;
				}
			}
		}
		if (best != -1) {
			fb_try_mode(var, info, &db[best], bpp);
			return (refresh_specified) ? 2 : 1;
		}

		diff = 2 * (xres + yres);
		best = -1;
		DPRINTK("Trying best-fit modes\n");
		for (i = 0; i < dbsize; i++) {
			DPRINTK("Trying %ix%i\n", db[i].xres, db[i].yres);
			if (!fb_try_mode(var, info, &db[i], bpp)) {
				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;
		}
	}

	DPRINTK("Trying default video mode\n");
	if (!fb_try_mode(var, info, default_mode, default_bpp))
		return 3;

	DPRINTK("Trying all modes\n");
	for (i = 0; i < dbsize; i++)
		if (!fb_try_mode(var, info, &db[i], default_bpp))
			return 4;

	DPRINTK("No valid mode found\n");
	return 0;
}