drivers/video/fbcvt.c - kernel/prism - Git at Google

 /*
  * 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 const unsigned char 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 = kzalloc(256, GFP_KERNEL);

 	if (!buf)
 		return;

 	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_back_porch;
 	mode->right_margin = cvt->h_front_porch;
 	mode->hsync_len = cvt->hsync;
 	mode->upper_margin = cvt->v_back_porch;
 	mode->lower_margin = cvt->v_front_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;
 }
	/*
	* 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 const unsigned char 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 = kzalloc(256, GFP_KERNEL);

	if (!buf)
	return;

	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_back_porch;
	mode->right_margin = cvt->h_front_porch;
	mode->hsync_len = cvt->hsync;
	mode->upper_margin = cvt->v_back_porch;
	mode->lower_margin = cvt->v_front_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;
	}