6 files changed, 519 insertions, 12 deletions

diff --git a/Documentation/fb/modedb.txt b/Documentation/fb/modedb.txt
index e04458b319d5..4fcdb4cf4cca 100644
--- a/Documentation/fb/modedb.txt
+++ b/Documentation/fb/modedb.txt
@@ -20,12 +20,83 @@ in a video= option, fbmem considers that to be a global video mode option.
 
 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,
diff --git a/drivers/video/Makefile b/drivers/video/Makefile
index 8478d217aaf0..4e7d8d27b913 100644
--- a/drivers/video/Makefile
+++ b/drivers/video/Makefile
@@ -9,7 +9,8 @@ obj-$(CONFIG_LOGO)		  += logo/
 obj-$(CONFIG_SYSFS)               += backlight/
 
 obj-$(CONFIG_FB)                  += fb.o
-fb-y                              := fbmem.o fbmon.o fbcmap.o fbsysfs.o modedb.o
+fb-y                              := fbmem.o fbmon.o fbcmap.o fbsysfs.o \
+                                     modedb.o fbcvt.o
 fb-objs                           := $(fb-y)
 
 obj-$(CONFIG_FB_CFB_FILLRECT)  += cfbfillrect.o
diff --git a/drivers/video/fbcvt.c b/drivers/video/fbcvt.c
new file mode 100644
index 000000000000..cfa61b512de0
--- /dev/null
+++ b/drivers/video/fbcvt.c
@@ -0,0 +1,380 @@
+/*
+ * 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);
diff --git a/drivers/video/fbmem.c b/drivers/video/fbmem.c
index a815f5e2fcb5..71b55070bdb9 100644
--- a/drivers/video/fbmem.c
+++ b/drivers/video/fbmem.c
@@ -1029,6 +1029,7 @@ register_framebuffer(struct fb_info *fb_info)
 {
         int i;
         struct fb_event event;
+        struct fb_videomode mode;
 
         if (num_registered_fb == FB_MAX)
                 return -ENXIO;
@@ -1059,16 +1060,11 @@ register_framebuffer(struct fb_info *fb_info)
         }       
         fb_info->pixmap.offset = 0;
 
-        if (!fb_info->modelist.prev ||
-            !fb_info->modelist.next ||
-            list_empty(&fb_info->modelist)) {
-                struct fb_videomode mode;
-
+        if (!fb_info->modelist.prev || !fb_info->modelist.next)
                 INIT_LIST_HEAD(&fb_info->modelist);
-                fb_var_to_videomode(&mode, &fb_info->var);
-                fb_add_videomode(&mode, &fb_info->modelist);
-        }
 
+        fb_var_to_videomode(&mode, &fb_info->var);
+        fb_add_videomode(&mode, &fb_info->modelist);
         registered_fb[i] = fb_info;
 
         devfs_mk_cdev(MKDEV(FB_MAJOR, i),
diff --git a/drivers/video/modedb.c b/drivers/video/modedb.c
index 3edc9f49344b..47516c44a390 100644
--- a/drivers/video/modedb.c
+++ b/drivers/video/modedb.c
@@ -456,12 +456,22 @@ static int fb_try_mode(struct fb_var_screeninfo *var, struct fb_info *info,
  *
  *      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.
  *
@@ -495,7 +505,7 @@ int fb_find_mode(struct fb_var_screeninfo *var,
         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--) {
@@ -506,6 +516,8 @@ int fb_find_mode(struct fb_var_screeninfo *var,
                         !yres_specified) {
                         refresh = my_atoi(&name[i+1]);
                         refresh_specified = 1;
+                        if (cvt || rb)
+                            cvt = 0;
                     } else
                         goto done;
                     break;
@@ -514,6 +526,8 @@ int fb_find_mode(struct fb_var_screeninfo *var,
                     if (!bpp_specified && !yres_specified) {
                         bpp = my_atoi(&name[i+1]);
                         bpp_specified = 1;
+                        if (cvt || rb)
+                            cvt = 0;
                     } else
                         goto done;
                     break;
@@ -526,6 +540,22 @@ int fb_find_mode(struct fb_var_screeninfo *var,
                     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;
             }
@@ -535,6 +565,34 @@ int fb_find_mode(struct fb_var_screeninfo *var,
             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);
 
diff --git a/include/linux/fb.h b/include/linux/fb.h
index 34814a0b2378..9a4f035e9fdc 100644
--- a/include/linux/fb.h
+++ b/include/linux/fb.h
@@ -866,6 +866,7 @@ extern const unsigned char *fb_firmware_edid(struct device *device);
 extern void fb_edid_to_monspecs(unsigned char *edid,
                                 struct fb_monspecs *specs);
 extern void fb_destroy_modedb(struct fb_videomode *modedb);
+extern int fb_find_mode_cvt(struct fb_videomode *mode, int margins, int rb);
 
 /* drivers/video/modedb.c */
 #define VESA_MODEDB_SIZE 34