Valid mode specifiers (mode_option argument):
- <xres>x<yres>[-<bpp>][@<refresh>]
+ <xres>x<yres>[M][R][-<bpp>][@<refresh>][i][m]
<name>[-<bpp>][@<refresh>]
with <xres>, <yres>, <bpp> and <refresh> decimal numbers and <name> a string.
Things between square brackets are optional.
+If 'M' is specified in the mode_option argument (after <yres> and before
+<bpp> and <refresh>, if specified) the timings will be calculated using
+VESA(TM) Coordinated Video Timings instead of looking up the mode from a table.
+If 'R' is specified, do a 'reduced blanking' calculation for digital displays.
+If 'i' is specified, calculate for an interlaced mode. And if 'm' is
+specified, add margins to the calculation (1.8% of xres rounded down to 8
+pixels and 1.8% of yres).
+
+ Sample usage: 1024x768M@60m - CVT timing with margins
+
+***** oOo ***** oOo ***** oOo ***** oOo ***** oOo ***** oOo ***** oOo *****
+
+What is the VESA(TM) Coordinated Video Timings (CVT)?
+
+From the VESA(TM) Website:
+
+ "The purpose of CVT is to provide a method for generating a consistent
+ and coordinated set of standard formats, display refresh rates, and
+ timing specifications for computer display products, both those
+ employing CRTs, and those using other display technologies. The
+ intention of CVT is to give both source and display manufacturers a
+ common set of tools to enable new timings to be developed in a
+ consistent manner that ensures greater compatibility."
+
+This is the third standard approved by VESA(TM) concerning video timings. The
+first was the Discrete Video Timings (DVT) which is a collection of
+pre-defined modes approved by VESA(TM). The second is the Generalized Timing
+Formula (GTF) which is an algorithm to calculate the timings, given the
+pixelclock, the horizontal sync frequency, or the vertical refresh rate.
+
+The GTF is limited by the fact that it is designed mainly for CRT displays.
+It artificially increases the pixelclock because of its high blanking
+requirement. This is inappropriate for digital display interface with its high
+data rate which requires that it conserves the pixelclock as much as possible.
+Also, GTF does not take into account the aspect ratio of the display.
+
+The CVT addresses these limitations. If used with CRT's, the formula used
+is a derivation of GTF with a few modifications. If used with digital
+displays, the "reduced blanking" calculation can be used.
+
+From the framebuffer subsystem perspective, new formats need not be added
+to the global mode database whenever a new mode is released by display
+manufacturers. Specifying for CVT will work for most, if not all, relatively
+new CRT displays and probably with most flatpanels, if 'reduced blanking'
+calculation is specified. (The CVT compatibility of the display can be
+determined from its EDID. The version 1.3 of the EDID has extra 128-byte
+blocks where additional timing information is placed. As of this time, there
+is no support yet in the layer to parse this additional blocks.)
+
+CVT also introduced a new naming convention (should be seen from dmesg output):
+
+ <pix>M<a>[-R]
+
+ where: pix = total amount of pixels in MB (xres x yres)
+ M = always present
+ a = aspect ratio (3 - 4:3; 4 - 5:4; 9 - 15:9, 16:9; A - 16:10)
+ -R = reduced blanking
+
+ example: .48M3-R - 800x600 with reduced blanking
+
+Note: VESA(TM) has restrictions on what is a standard CVT timing:
+
+ - aspect ratio can only be one of the above values
+ - acceptable refresh rates are 50, 60, 70 or 85 Hz only
+ - if reduced blanking, the refresh rate must be at 60Hz
+
+If one of the above are not satisfied, the kernel will print a warning but the
+timings will still be calculated.
+
+***** oOo ***** oOo ***** oOo ***** oOo ***** oOo ***** oOo ***** oOo *****
+
To find a suitable video mode, you just call
int __init fb_find_mode(struct fb_var_screeninfo *var,
--- /dev/null
+/*
+ * linux/drivers/video/fbcvt.c - VESA(TM) Coordinated Video Timings
+ *
+ * Copyright (C) 2005 Antonino Daplas <adaplas@pol.net>
+ *
+ * Based from the VESA(TM) Coordinated Video Timing Generator by
+ * Graham Loveridge April 9, 2003 available at
+ * http://www.vesa.org/public/CVT/CVTd6r1.xls
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file COPYING in the main directory of this archive
+ * for more details.
+ *
+ */
+#include <linux/fb.h>
+
+#define FB_CVT_CELLSIZE 8
+#define FB_CVT_GTF_C 40
+#define FB_CVT_GTF_J 20
+#define FB_CVT_GTF_K 128
+#define FB_CVT_GTF_M 600
+#define FB_CVT_MIN_VSYNC_BP 550
+#define FB_CVT_MIN_VPORCH 3
+#define FB_CVT_MIN_BPORCH 6
+
+#define FB_CVT_RB_MIN_VBLANK 460
+#define FB_CVT_RB_HBLANK 160
+#define FB_CVT_RB_V_FPORCH 3
+
+#define FB_CVT_FLAG_REDUCED_BLANK 1
+#define FB_CVT_FLAG_MARGINS 2
+#define FB_CVT_FLAG_INTERLACED 4
+
+struct fb_cvt_data {
+ u32 xres;
+ u32 yres;
+ u32 refresh;
+ u32 f_refresh;
+ u32 pixclock;
+ u32 hperiod;
+ u32 hblank;
+ u32 hfreq;
+ u32 htotal;
+ u32 vtotal;
+ u32 vsync;
+ u32 hsync;
+ u32 h_front_porch;
+ u32 h_back_porch;
+ u32 v_front_porch;
+ u32 v_back_porch;
+ u32 h_margin;
+ u32 v_margin;
+ u32 interlace;
+ u32 aspect_ratio;
+ u32 active_pixels;
+ u32 flags;
+ u32 status;
+};
+
+static int fb_cvt_vbi_tab[] = {
+ 4, /* 4:3 */
+ 5, /* 16:9 */
+ 6, /* 16:10 */
+ 7, /* 5:4 */
+ 7, /* 15:9 */
+ 8, /* reserved */
+ 9, /* reserved */
+ 10 /* custom */
+};
+
+/* returns hperiod * 1000 */
+static u32 fb_cvt_hperiod(struct fb_cvt_data *cvt)
+{
+ u32 num = 1000000000/cvt->f_refresh;
+ u32 den;
+
+ if (cvt->flags & FB_CVT_FLAG_REDUCED_BLANK) {
+ num -= FB_CVT_RB_MIN_VBLANK * 1000;
+ den = 2 * (cvt->yres/cvt->interlace + 2 * cvt->v_margin);
+ } else {
+ num -= FB_CVT_MIN_VSYNC_BP * 1000;
+ den = 2 * (cvt->yres/cvt->interlace + cvt->v_margin * 2
+ + FB_CVT_MIN_VPORCH + cvt->interlace/2);
+ }
+
+ return 2 * (num/den);
+}
+
+/* returns ideal duty cycle * 1000 */
+static u32 fb_cvt_ideal_duty_cycle(struct fb_cvt_data *cvt)
+{
+ u32 c_prime = (FB_CVT_GTF_C - FB_CVT_GTF_J) *
+ (FB_CVT_GTF_K) + 256 * FB_CVT_GTF_J;
+ u32 m_prime = (FB_CVT_GTF_K * FB_CVT_GTF_M);
+ u32 h_period_est = cvt->hperiod;
+
+ return (1000 * c_prime - ((m_prime * h_period_est)/1000))/256;
+}
+
+static u32 fb_cvt_hblank(struct fb_cvt_data *cvt)
+{
+ u32 hblank = 0;
+
+ if (cvt->flags & FB_CVT_FLAG_REDUCED_BLANK)
+ hblank = FB_CVT_RB_HBLANK;
+ else {
+ u32 ideal_duty_cycle = fb_cvt_ideal_duty_cycle(cvt);
+ u32 active_pixels = cvt->active_pixels;
+
+ if (ideal_duty_cycle < 20000)
+ hblank = (active_pixels * 20000)/
+ (100000 - 20000);
+ else {
+ hblank = (active_pixels * ideal_duty_cycle)/
+ (100000 - ideal_duty_cycle);
+ }
+ }
+
+ hblank &= ~((2 * FB_CVT_CELLSIZE) - 1);
+
+ return hblank;
+}
+
+static u32 fb_cvt_hsync(struct fb_cvt_data *cvt)
+{
+ u32 hsync;
+
+ if (cvt->flags & FB_CVT_FLAG_REDUCED_BLANK)
+ hsync = 32;
+ else
+ hsync = (FB_CVT_CELLSIZE * cvt->htotal)/100;
+
+ hsync &= ~(FB_CVT_CELLSIZE - 1);
+ return hsync;
+}
+
+static u32 fb_cvt_vbi_lines(struct fb_cvt_data *cvt)
+{
+ u32 vbi_lines, min_vbi_lines, act_vbi_lines;
+
+ if (cvt->flags & FB_CVT_FLAG_REDUCED_BLANK) {
+ vbi_lines = (1000 * FB_CVT_RB_MIN_VBLANK)/cvt->hperiod + 1;
+ min_vbi_lines = FB_CVT_RB_V_FPORCH + cvt->vsync +
+ FB_CVT_MIN_BPORCH;
+
+ } else {
+ vbi_lines = (FB_CVT_MIN_VSYNC_BP * 1000)/cvt->hperiod + 1 +
+ FB_CVT_MIN_VPORCH;
+ min_vbi_lines = cvt->vsync + FB_CVT_MIN_BPORCH +
+ FB_CVT_MIN_VPORCH;
+ }
+
+ if (vbi_lines < min_vbi_lines)
+ act_vbi_lines = min_vbi_lines;
+ else
+ act_vbi_lines = vbi_lines;
+
+ return act_vbi_lines;
+}
+
+static u32 fb_cvt_vtotal(struct fb_cvt_data *cvt)
+{
+ u32 vtotal = cvt->yres/cvt->interlace;
+
+ vtotal += 2 * cvt->v_margin + cvt->interlace/2 + fb_cvt_vbi_lines(cvt);
+ vtotal |= cvt->interlace/2;
+
+ return vtotal;
+}
+
+static u32 fb_cvt_pixclock(struct fb_cvt_data *cvt)
+{
+ u32 pixclock;
+
+ if (cvt->flags & FB_CVT_FLAG_REDUCED_BLANK)
+ pixclock = (cvt->f_refresh * cvt->vtotal * cvt->htotal)/1000;
+ else
+ pixclock = (cvt->htotal * 1000000)/cvt->hperiod;
+
+ pixclock /= 250;
+ pixclock *= 250;
+ pixclock *= 1000;
+
+ return pixclock;
+}
+
+static u32 fb_cvt_aspect_ratio(struct fb_cvt_data *cvt)
+{
+ u32 xres = cvt->xres;
+ u32 yres = cvt->yres;
+ u32 aspect = -1;
+
+ if (xres == (yres * 4)/3 && !((yres * 4) % 3))
+ aspect = 0;
+ else if (xres == (yres * 16)/9 && !((yres * 16) % 9))
+ aspect = 1;
+ else if (xres == (yres * 16)/10 && !((yres * 16) % 10))
+ aspect = 2;
+ else if (xres == (yres * 5)/4 && !((yres * 5) % 4))
+ aspect = 3;
+ else if (xres == (yres * 15)/9 && !((yres * 15) % 9))
+ aspect = 4;
+ else {
+ printk(KERN_INFO "fbcvt: Aspect ratio not CVT "
+ "standard\n");
+ aspect = 7;
+ cvt->status = 1;
+ }
+
+ return aspect;
+}
+
+static void fb_cvt_print_name(struct fb_cvt_data *cvt)
+{
+ u32 pixcount, pixcount_mod;
+ int cnt = 255, offset = 0, read = 0;
+ u8 *buf = kmalloc(256, GFP_KERNEL);
+
+ if (!buf)
+ return;
+
+ memset(buf, 0, 256);
+ pixcount = (cvt->xres * (cvt->yres/cvt->interlace))/1000000;
+ pixcount_mod = (cvt->xres * (cvt->yres/cvt->interlace)) % 1000000;
+ pixcount_mod /= 1000;
+
+ read = snprintf(buf+offset, cnt, "fbcvt: %dx%d@%d: CVT Name - ",
+ cvt->xres, cvt->yres, cvt->refresh);
+ offset += read;
+ cnt -= read;
+
+ if (cvt->status)
+ snprintf(buf+offset, cnt, "Not a CVT standard - %d.%03d Mega "
+ "Pixel Image\n", pixcount, pixcount_mod);
+ else {
+ if (pixcount) {
+ read = snprintf(buf+offset, cnt, "%d", pixcount);
+ cnt -= read;
+ offset += read;
+ }
+
+ read = snprintf(buf+offset, cnt, ".%03dM", pixcount_mod);
+ cnt -= read;
+ offset += read;
+
+ if (cvt->aspect_ratio == 0)
+ read = snprintf(buf+offset, cnt, "3");
+ else if (cvt->aspect_ratio == 3)
+ read = snprintf(buf+offset, cnt, "4");
+ else if (cvt->aspect_ratio == 1 || cvt->aspect_ratio == 4)
+ read = snprintf(buf+offset, cnt, "9");
+ else if (cvt->aspect_ratio == 2)
+ read = snprintf(buf+offset, cnt, "A");
+ else
+ read = 0;
+ cnt -= read;
+ offset += read;
+
+ if (cvt->flags & FB_CVT_FLAG_REDUCED_BLANK) {
+ read = snprintf(buf+offset, cnt, "-R");
+ cnt -= read;
+ offset += read;
+ }
+ }
+
+ printk(KERN_INFO "%s\n", buf);
+ kfree(buf);
+}
+
+static void fb_cvt_convert_to_mode(struct fb_cvt_data *cvt,
+ struct fb_videomode *mode)
+{
+ mode->refresh = cvt->f_refresh;
+ mode->pixclock = KHZ2PICOS(cvt->pixclock/1000);
+ mode->left_margin = cvt->h_front_porch;
+ mode->right_margin = cvt->h_back_porch;
+ mode->hsync_len = cvt->hsync;
+ mode->upper_margin = cvt->v_front_porch;
+ mode->lower_margin = cvt->v_back_porch;
+ mode->vsync_len = cvt->vsync;
+
+ mode->sync &= ~(FB_SYNC_HOR_HIGH_ACT | FB_SYNC_VERT_HIGH_ACT);
+
+ if (cvt->flags & FB_CVT_FLAG_REDUCED_BLANK)
+ mode->sync |= FB_SYNC_HOR_HIGH_ACT;
+ else
+ mode->sync |= FB_SYNC_VERT_HIGH_ACT;
+}
+
+/*
+ * fb_find_mode_cvt - calculate mode using VESA(TM) CVT
+ * @mode: pointer to fb_videomode; xres, yres, refresh and vmode must be
+ * pre-filled with the desired values
+ * @margins: add margin to calculation (1.8% of xres and yres)
+ * @rb: compute with reduced blanking (for flatpanels)
+ *
+ * RETURNS:
+ * 0 for success
+ * @mode is filled with computed values. If interlaced, the refresh field
+ * will be filled with the field rate (2x the frame rate)
+ *
+ * DESCRIPTION:
+ * Computes video timings using VESA(TM) Coordinated Video Timings
+ */
+int fb_find_mode_cvt(struct fb_videomode *mode, int margins, int rb)
+{
+ struct fb_cvt_data cvt;
+
+ memset(&cvt, 0, sizeof(cvt));
+
+ if (margins)
+ cvt.flags |= FB_CVT_FLAG_MARGINS;
+
+ if (rb)
+ cvt.flags |= FB_CVT_FLAG_REDUCED_BLANK;
+
+ if (mode->vmode & FB_VMODE_INTERLACED)
+ cvt.flags |= FB_CVT_FLAG_INTERLACED;
+
+ cvt.xres = mode->xres;
+ cvt.yres = mode->yres;
+ cvt.refresh = mode->refresh;
+ cvt.f_refresh = cvt.refresh;
+ cvt.interlace = 1;
+
+ if (!cvt.xres || !cvt.yres || !cvt.refresh) {
+ printk(KERN_INFO "fbcvt: Invalid input parameters\n");
+ return 1;
+ }
+
+ if (!(cvt.refresh == 50 || cvt.refresh == 60 || cvt.refresh == 70 ||
+ cvt.refresh == 85)) {
+ printk(KERN_INFO "fbcvt: Refresh rate not CVT "
+ "standard\n");
+ cvt.status = 1;
+ }
+
+ cvt.xres &= ~(FB_CVT_CELLSIZE - 1);
+
+ if (cvt.flags & FB_CVT_FLAG_INTERLACED) {
+ cvt.interlace = 2;
+ cvt.f_refresh *= 2;
+ }
+
+ if (cvt.flags & FB_CVT_FLAG_REDUCED_BLANK) {
+ if (cvt.refresh != 60) {
+ printk(KERN_INFO "fbcvt: 60Hz refresh rate "
+ "advised for reduced blanking\n");
+ cvt.status = 1;
+ }
+ }
+
+ if (cvt.flags & FB_CVT_FLAG_MARGINS) {
+ cvt.h_margin = (cvt.xres * 18)/1000;
+ cvt.h_margin &= ~(FB_CVT_CELLSIZE - 1);
+ cvt.v_margin = ((cvt.yres/cvt.interlace)* 18)/1000;
+ }
+
+ cvt.aspect_ratio = fb_cvt_aspect_ratio(&cvt);
+ cvt.active_pixels = cvt.xres + 2 * cvt.h_margin;
+ cvt.hperiod = fb_cvt_hperiod(&cvt);
+ cvt.vsync = fb_cvt_vbi_tab[cvt.aspect_ratio];
+ cvt.vtotal = fb_cvt_vtotal(&cvt);
+ cvt.hblank = fb_cvt_hblank(&cvt);
+ cvt.htotal = cvt.active_pixels + cvt.hblank;
+ cvt.hsync = fb_cvt_hsync(&cvt);
+ cvt.pixclock = fb_cvt_pixclock(&cvt);
+ cvt.hfreq = cvt.pixclock/cvt.htotal;
+ cvt.h_back_porch = cvt.hblank/2 + cvt.h_margin;
+ cvt.h_front_porch = cvt.hblank - cvt.hsync - cvt.h_back_porch +
+ 2 * cvt.h_margin;
+ cvt.v_back_porch = 3 + cvt.v_margin;
+ cvt.v_front_porch = cvt.vtotal - cvt.yres/cvt.interlace -
+ cvt.v_back_porch - cvt.vsync;
+ fb_cvt_print_name(&cvt);
+ fb_cvt_convert_to_mode(&cvt, mode);
+
+ return 0;
+}
+EXPORT_SYMBOL(fb_find_mode_cvt);
*
* Valid mode specifiers for @mode_option:
*
- * <xres>x<yres>[-<bpp>][@<refresh>] or
+ * <xres>x<yres>[M][R][-<bpp>][@<refresh>][i][m] or
* <name>[-<bpp>][@<refresh>]
*
* with <xres>, <yres>, <bpp> and <refresh> decimal numbers and
* <name> a string.
*
+ * If 'M' is present after yres (and before refresh/bpp if present),
+ * the function will compute the timings using VESA(tm) Coordinated
+ * Video Timings (CVT). If 'R' is present after 'M', will compute with
+ * reduced blanking (for flatpanels). If 'i' is present, compute
+ * interlaced mode. If 'm' is present, add margins equal to 1.8%
+ * of xres rounded down to 8 pixels, and 1.8% of yres. The char
+ * 'i' and 'm' must be after 'M' and 'R'. Example:
+ *
+ * 1024x768MR-8@60m - Reduced blank with margins at 60Hz.
+ *
* NOTE: The passed struct @var is _not_ cleared! This allows you
* to supply values for e.g. the grayscale and accel_flags fields.
*
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;
+ int yres_specified = 0, cvt = 0, rb = 0, interlace = 0, margins = 0;
u32 best, diff;
for (i = namelen-1; i >= 0; i--) {
!yres_specified) {
refresh = my_atoi(&name[i+1]);
refresh_specified = 1;
+ if (cvt || rb)
+ cvt = 0;
} else
goto done;
break;
if (!bpp_specified && !yres_specified) {
bpp = my_atoi(&name[i+1]);
bpp_specified = 1;
+ if (cvt || rb)
+ cvt = 0;
} else
goto done;
break;
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 'i':
+ if (!cvt)
+ interlace = 1;
+ break;
default:
goto done;
}
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" : "");
+
+ 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);
projects / GitHub / LineageOS / android_kernel_motorola_exynos9610.git / commitdiff