drivers/media/v4l2-core/v4l2-dv-timings.c - kernel/msm-4.19 - Gitiles

 /*
  * v4l2-dv-timings - dv-timings helper functions
  *
  * Copyright 2013 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
  *
  * This program is free software; you may redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; version 2 of the License.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  *
  */

 #include <linux/module.h>
 #include <linux/types.h>
 #include <linux/kernel.h>
 #include <linux/errno.h>
 #include <linux/videodev2.h>
 #include <linux/v4l2-dv-timings.h>
 #include <media/v4l2-dv-timings.h>

 MODULE_AUTHOR("Hans Verkuil");
 MODULE_DESCRIPTION("V4L2 DV Timings Helper Functions");
 MODULE_LICENSE("GPL");

 const struct v4l2_dv_timings v4l2_dv_timings_presets[] = {
 	V4L2_DV_BT_CEA_640X480P59_94,
 	V4L2_DV_BT_CEA_720X480I59_94,
 	V4L2_DV_BT_CEA_720X480P59_94,
 	V4L2_DV_BT_CEA_720X576I50,
 	V4L2_DV_BT_CEA_720X576P50,
 	V4L2_DV_BT_CEA_1280X720P24,
 	V4L2_DV_BT_CEA_1280X720P25,
 	V4L2_DV_BT_CEA_1280X720P30,
 	V4L2_DV_BT_CEA_1280X720P50,
 	V4L2_DV_BT_CEA_1280X720P60,
 	V4L2_DV_BT_CEA_1920X1080P24,
 	V4L2_DV_BT_CEA_1920X1080P25,
 	V4L2_DV_BT_CEA_1920X1080P30,
 	V4L2_DV_BT_CEA_1920X1080I50,
 	V4L2_DV_BT_CEA_1920X1080P50,
 	V4L2_DV_BT_CEA_1920X1080I60,
 	V4L2_DV_BT_CEA_1920X1080P60,
 	V4L2_DV_BT_DMT_640X350P85,
 	V4L2_DV_BT_DMT_640X400P85,
 	V4L2_DV_BT_DMT_720X400P85,
 	V4L2_DV_BT_DMT_640X480P72,
 	V4L2_DV_BT_DMT_640X480P75,
 	V4L2_DV_BT_DMT_640X480P85,
 	V4L2_DV_BT_DMT_800X600P56,
 	V4L2_DV_BT_DMT_800X600P60,
 	V4L2_DV_BT_DMT_800X600P72,
 	V4L2_DV_BT_DMT_800X600P75,
 	V4L2_DV_BT_DMT_800X600P85,
 	V4L2_DV_BT_DMT_800X600P120_RB,
 	V4L2_DV_BT_DMT_848X480P60,
 	V4L2_DV_BT_DMT_1024X768I43,
 	V4L2_DV_BT_DMT_1024X768P60,
 	V4L2_DV_BT_DMT_1024X768P70,
 	V4L2_DV_BT_DMT_1024X768P75,
 	V4L2_DV_BT_DMT_1024X768P85,
 	V4L2_DV_BT_DMT_1024X768P120_RB,
 	V4L2_DV_BT_DMT_1152X864P75,
 	V4L2_DV_BT_DMT_1280X768P60_RB,
 	V4L2_DV_BT_DMT_1280X768P60,
 	V4L2_DV_BT_DMT_1280X768P75,
 	V4L2_DV_BT_DMT_1280X768P85,
 	V4L2_DV_BT_DMT_1280X768P120_RB,
 	V4L2_DV_BT_DMT_1280X800P60_RB,
 	V4L2_DV_BT_DMT_1280X800P60,
 	V4L2_DV_BT_DMT_1280X800P75,
 	V4L2_DV_BT_DMT_1280X800P85,
 	V4L2_DV_BT_DMT_1280X800P120_RB,
 	V4L2_DV_BT_DMT_1280X960P60,
 	V4L2_DV_BT_DMT_1280X960P85,
 	V4L2_DV_BT_DMT_1280X960P120_RB,
 	V4L2_DV_BT_DMT_1280X1024P60,
 	V4L2_DV_BT_DMT_1280X1024P75,
 	V4L2_DV_BT_DMT_1280X1024P85,
 	V4L2_DV_BT_DMT_1280X1024P120_RB,
 	V4L2_DV_BT_DMT_1360X768P60,
 	V4L2_DV_BT_DMT_1360X768P120_RB,
 	V4L2_DV_BT_DMT_1366X768P60,
 	V4L2_DV_BT_DMT_1366X768P60_RB,
 	V4L2_DV_BT_DMT_1400X1050P60_RB,
 	V4L2_DV_BT_DMT_1400X1050P60,
 	V4L2_DV_BT_DMT_1400X1050P75,
 	V4L2_DV_BT_DMT_1400X1050P85,
 	V4L2_DV_BT_DMT_1400X1050P120_RB,
 	V4L2_DV_BT_DMT_1440X900P60_RB,
 	V4L2_DV_BT_DMT_1440X900P60,
 	V4L2_DV_BT_DMT_1440X900P75,
 	V4L2_DV_BT_DMT_1440X900P85,
 	V4L2_DV_BT_DMT_1440X900P120_RB,
 	V4L2_DV_BT_DMT_1600X900P60_RB,
 	V4L2_DV_BT_DMT_1600X1200P60,
 	V4L2_DV_BT_DMT_1600X1200P65,
 	V4L2_DV_BT_DMT_1600X1200P70,
 	V4L2_DV_BT_DMT_1600X1200P75,
 	V4L2_DV_BT_DMT_1600X1200P85,
 	V4L2_DV_BT_DMT_1600X1200P120_RB,
 	V4L2_DV_BT_DMT_1680X1050P60_RB,
 	V4L2_DV_BT_DMT_1680X1050P60,
 	V4L2_DV_BT_DMT_1680X1050P75,
 	V4L2_DV_BT_DMT_1680X1050P85,
 	V4L2_DV_BT_DMT_1680X1050P120_RB,
 	V4L2_DV_BT_DMT_1792X1344P60,
 	V4L2_DV_BT_DMT_1792X1344P75,
 	V4L2_DV_BT_DMT_1792X1344P120_RB,
 	V4L2_DV_BT_DMT_1856X1392P60,
 	V4L2_DV_BT_DMT_1856X1392P75,
 	V4L2_DV_BT_DMT_1856X1392P120_RB,
 	V4L2_DV_BT_DMT_1920X1200P60_RB,
 	V4L2_DV_BT_DMT_1920X1200P60,
 	V4L2_DV_BT_DMT_1920X1200P75,
 	V4L2_DV_BT_DMT_1920X1200P85,
 	V4L2_DV_BT_DMT_1920X1200P120_RB,
 	V4L2_DV_BT_DMT_1920X1440P60,
 	V4L2_DV_BT_DMT_1920X1440P75,
 	V4L2_DV_BT_DMT_1920X1440P120_RB,
 	V4L2_DV_BT_DMT_2048X1152P60_RB,
 	V4L2_DV_BT_DMT_2560X1600P60_RB,
 	V4L2_DV_BT_DMT_2560X1600P60,
 	V4L2_DV_BT_DMT_2560X1600P75,
 	V4L2_DV_BT_DMT_2560X1600P85,
 	V4L2_DV_BT_DMT_2560X1600P120_RB,
 	V4L2_DV_BT_CEA_3840X2160P24,
 	V4L2_DV_BT_CEA_3840X2160P25,
 	V4L2_DV_BT_CEA_3840X2160P30,
 	V4L2_DV_BT_CEA_3840X2160P50,
 	V4L2_DV_BT_CEA_3840X2160P60,
 	V4L2_DV_BT_CEA_4096X2160P24,
 	V4L2_DV_BT_CEA_4096X2160P25,
 	V4L2_DV_BT_CEA_4096X2160P30,
 	V4L2_DV_BT_CEA_4096X2160P50,
 	V4L2_DV_BT_DMT_4096X2160P59_94_RB,
 	V4L2_DV_BT_CEA_4096X2160P60,
 	{ }
 };
 EXPORT_SYMBOL_GPL(v4l2_dv_timings_presets);

 bool v4l2_valid_dv_timings(const struct v4l2_dv_timings *t,
 			   const struct v4l2_dv_timings_cap *dvcap,
 			   v4l2_check_dv_timings_fnc fnc,
 			   void *fnc_handle)
 {
 	const struct v4l2_bt_timings *bt = &t->bt;
 	const struct v4l2_bt_timings_cap *cap = &dvcap->bt;
 	u32 caps = cap->capabilities;

 	if (t->type != V4L2_DV_BT_656_1120)
 		return false;
 	if (t->type != dvcap->type ||
 	    bt->height < cap->min_height ||
 	    bt->height > cap->max_height ||
 	    bt->width < cap->min_width ||
 	    bt->width > cap->max_width ||
 	    bt->pixelclock < cap->min_pixelclock ||
 	    bt->pixelclock > cap->max_pixelclock ||
 	    (cap->standards && bt->standards &&
 	     !(bt->standards & cap->standards)) ||
 	    (bt->interlaced && !(caps & V4L2_DV_BT_CAP_INTERLACED)) ||
 	    (!bt->interlaced && !(caps & V4L2_DV_BT_CAP_PROGRESSIVE)))
 		return false;
 	return fnc == NULL || fnc(t, fnc_handle);
 }
 EXPORT_SYMBOL_GPL(v4l2_valid_dv_timings);

 int v4l2_enum_dv_timings_cap(struct v4l2_enum_dv_timings *t,
 			     const struct v4l2_dv_timings_cap *cap,
 			     v4l2_check_dv_timings_fnc fnc,
 			     void *fnc_handle)
 {
 	u32 i, idx;

 	memset(t->reserved, 0, sizeof(t->reserved));
 	for (i = idx = 0; v4l2_dv_timings_presets[i].bt.width; i++) {
 		if (v4l2_valid_dv_timings(v4l2_dv_timings_presets + i, cap,
 					  fnc, fnc_handle) &&
 		    idx++ == t->index) {
 			t->timings = v4l2_dv_timings_presets[i];
 			return 0;
 		}
 	}
 	return -EINVAL;
 }
 EXPORT_SYMBOL_GPL(v4l2_enum_dv_timings_cap);

 bool v4l2_find_dv_timings_cap(struct v4l2_dv_timings *t,
 			      const struct v4l2_dv_timings_cap *cap,
 			      unsigned pclock_delta,
 			      v4l2_check_dv_timings_fnc fnc,
 			      void *fnc_handle)
 {
 	int i;

 	if (!v4l2_valid_dv_timings(t, cap, fnc, fnc_handle))
 		return false;

 	for (i = 0; i < v4l2_dv_timings_presets[i].bt.width; i++) {
 		if (v4l2_valid_dv_timings(v4l2_dv_timings_presets + i, cap,
 					  fnc, fnc_handle) &&
 		    v4l2_match_dv_timings(t, v4l2_dv_timings_presets + i,
 					  pclock_delta)) {
 			*t = v4l2_dv_timings_presets[i];
 			return true;
 		}
 	}
 	return false;
 }
 EXPORT_SYMBOL_GPL(v4l2_find_dv_timings_cap);

 /**
  * v4l2_match_dv_timings - check if two timings match
  * @t1 - compare this v4l2_dv_timings struct...
  * @t2 - with this struct.
  * @pclock_delta - the allowed pixelclock deviation.
  *
  * Compare t1 with t2 with a given margin of error for the pixelclock.
  */
 bool v4l2_match_dv_timings(const struct v4l2_dv_timings *t1,
 			   const struct v4l2_dv_timings *t2,
 			   unsigned pclock_delta)
 {
 	if (t1->type != t2->type || t1->type != V4L2_DV_BT_656_1120)
 		return false;
 	if (t1->bt.width == t2->bt.width &&
 	    t1->bt.height == t2->bt.height &&
 	    t1->bt.interlaced == t2->bt.interlaced &&
 	    t1->bt.polarities == t2->bt.polarities &&
 	    t1->bt.pixelclock >= t2->bt.pixelclock - pclock_delta &&
 	    t1->bt.pixelclock <= t2->bt.pixelclock + pclock_delta &&
 	    t1->bt.hfrontporch == t2->bt.hfrontporch &&
 	    t1->bt.vfrontporch == t2->bt.vfrontporch &&
 	    t1->bt.vsync == t2->bt.vsync &&
 	    t1->bt.vbackporch == t2->bt.vbackporch &&
 	    (!t1->bt.interlaced ||
 		(t1->bt.il_vfrontporch == t2->bt.il_vfrontporch &&
 		 t1->bt.il_vsync == t2->bt.il_vsync &&
 		 t1->bt.il_vbackporch == t2->bt.il_vbackporch)))
 		return true;
 	return false;
 }
 EXPORT_SYMBOL_GPL(v4l2_match_dv_timings);

 void v4l2_print_dv_timings(const char *dev_prefix, const char *prefix,
 			   const struct v4l2_dv_timings *t, bool detailed)
 {
 	const struct v4l2_bt_timings *bt = &t->bt;
 	u32 htot, vtot;

 	if (t->type != V4L2_DV_BT_656_1120)
 		return;

 	htot = V4L2_DV_BT_FRAME_WIDTH(bt);
 	vtot = V4L2_DV_BT_FRAME_HEIGHT(bt);

 	if (prefix == NULL)
 		prefix = "";

 	pr_info("%s: %s%ux%u%s%u (%ux%u)\n", dev_prefix, prefix,
 		bt->width, bt->height, bt->interlaced ? "i" : "p",
 		(htot * vtot) > 0 ? ((u32)bt->pixelclock / (htot * vtot)) : 0,
 		htot, vtot);

 	if (!detailed)
 		return;

 	pr_info("%s: horizontal: fp = %u, %ssync = %u, bp = %u\n",
 			dev_prefix, bt->hfrontporch,
 			(bt->polarities & V4L2_DV_HSYNC_POS_POL) ? "+" : "-",
 			bt->hsync, bt->hbackporch);
 	pr_info("%s: vertical: fp = %u, %ssync = %u, bp = %u\n",
 			dev_prefix, bt->vfrontporch,
 			(bt->polarities & V4L2_DV_VSYNC_POS_POL) ? "+" : "-",
 			bt->vsync, bt->vbackporch);
 	pr_info("%s: pixelclock: %llu\n", dev_prefix, bt->pixelclock);
 	pr_info("%s: flags (0x%x):%s%s%s%s\n", dev_prefix, bt->flags,
 			(bt->flags & V4L2_DV_FL_REDUCED_BLANKING) ?
 			" REDUCED_BLANKING" : "",
 			(bt->flags & V4L2_DV_FL_CAN_REDUCE_FPS) ?
 			" CAN_REDUCE_FPS" : "",
 			(bt->flags & V4L2_DV_FL_REDUCED_FPS) ?
 			" REDUCED_FPS" : "",
 			(bt->flags & V4L2_DV_FL_HALF_LINE) ?
 			" HALF_LINE" : "");
 	pr_info("%s: standards (0x%x):%s%s%s%s\n", dev_prefix, bt->standards,
 			(bt->standards & V4L2_DV_BT_STD_CEA861) ?  " CEA" : "",
 			(bt->standards & V4L2_DV_BT_STD_DMT) ?  " DMT" : "",
 			(bt->standards & V4L2_DV_BT_STD_CVT) ?  " CVT" : "",
 			(bt->standards & V4L2_DV_BT_STD_GTF) ?  " GTF" : "");
 }
 EXPORT_SYMBOL_GPL(v4l2_print_dv_timings);

 /*
  * CVT defines
  * Based on Coordinated Video Timings Standard
  * version 1.1 September 10, 2003
  */

 #define CVT_PXL_CLK_GRAN	250000	/* pixel clock granularity */

 /* Normal blanking */
 #define CVT_MIN_V_BPORCH	7	/* lines */
 #define CVT_MIN_V_PORCH_RND	3	/* lines */
 #define CVT_MIN_VSYNC_BP	550	/* min time of vsync + back porch (us) */

 /* Normal blanking for CVT uses GTF to calculate horizontal blanking */
 #define CVT_CELL_GRAN		8	/* character cell granularity */
 #define CVT_M			600	/* blanking formula gradient */
 #define CVT_C			40	/* blanking formula offset */
 #define CVT_K			128	/* blanking formula scaling factor */
 #define CVT_J			20	/* blanking formula scaling factor */
 #define CVT_C_PRIME (((CVT_C - CVT_J) * CVT_K / 256) + CVT_J)
 #define CVT_M_PRIME (CVT_K * CVT_M / 256)

 /* Reduced Blanking */
 #define CVT_RB_MIN_V_BPORCH    7       /* lines  */
 #define CVT_RB_V_FPORCH        3       /* lines  */
 #define CVT_RB_MIN_V_BLANK   460     /* us     */
 #define CVT_RB_H_SYNC         32       /* pixels */
 #define CVT_RB_H_BPORCH       80       /* pixels */
 #define CVT_RB_H_BLANK       160       /* pixels */

 /** v4l2_detect_cvt - detect if the given timings follow the CVT standard
  * @frame_height - the total height of the frame (including blanking) in lines.
  * @hfreq - the horizontal frequency in Hz.
  * @vsync - the height of the vertical sync in lines.
  * @polarities - the horizontal and vertical polarities (same as struct
  *		v4l2_bt_timings polarities).
  * @fmt - the resulting timings.
  *
  * This function will attempt to detect if the given values correspond to a
  * valid CVT format. If so, then it will return true, and fmt will be filled
  * in with the found CVT timings.
  *
  * TODO: VESA defined a new version 2 of their reduced blanking
  * formula. Support for that is currently missing in this CVT
  * detection function.
  */
 bool v4l2_detect_cvt(unsigned frame_height, unsigned hfreq, unsigned vsync,
 		u32 polarities, struct v4l2_dv_timings *fmt)
 {
 	int  v_fp, v_bp, h_fp, h_bp, hsync;
 	int  frame_width, image_height, image_width;
 	bool reduced_blanking;
 	unsigned pix_clk;

 	if (vsync < 4 || vsync > 7)
 		return false;

 	if (polarities == V4L2_DV_VSYNC_POS_POL)
 		reduced_blanking = false;
 	else if (polarities == V4L2_DV_HSYNC_POS_POL)
 		reduced_blanking = true;
 	else
 		return false;

 	/* Vertical */
 	if (reduced_blanking) {
 		v_fp = CVT_RB_V_FPORCH;
 		v_bp = (CVT_RB_MIN_V_BLANK * hfreq + 1999999) / 1000000;
 		v_bp -= vsync + v_fp;

 		if (v_bp < CVT_RB_MIN_V_BPORCH)
 			v_bp = CVT_RB_MIN_V_BPORCH;
 	} else {
 		v_fp = CVT_MIN_V_PORCH_RND;
 		v_bp = (CVT_MIN_VSYNC_BP * hfreq + 1999999) / 1000000 - vsync;

 		if (v_bp < CVT_MIN_V_BPORCH)
 			v_bp = CVT_MIN_V_BPORCH;
 	}
 	image_height = (frame_height - v_fp - vsync - v_bp + 1) & ~0x1;

 	/* Aspect ratio based on vsync */
 	switch (vsync) {
 	case 4:
 		image_width = (image_height * 4) / 3;
 		break;
 	case 5:
 		image_width = (image_height * 16) / 9;
 		break;
 	case 6:
 		image_width = (image_height * 16) / 10;
 		break;
 	case 7:
 		/* special case */
 		if (image_height == 1024)
 			image_width = (image_height * 5) / 4;
 		else if (image_height == 768)
 			image_width = (image_height * 15) / 9;
 		else
 			return false;
 		break;
 	default:
 		return false;
 	}

 	image_width = image_width & ~7;

 	/* Horizontal */
 	if (reduced_blanking) {
 		pix_clk = (image_width + CVT_RB_H_BLANK) * hfreq;
 		pix_clk = (pix_clk / CVT_PXL_CLK_GRAN) * CVT_PXL_CLK_GRAN;

 		h_bp = CVT_RB_H_BPORCH;
 		hsync = CVT_RB_H_SYNC;
 		h_fp = CVT_RB_H_BLANK - h_bp - hsync;

 		frame_width = image_width + CVT_RB_H_BLANK;
 	} else {
 		unsigned ideal_duty_cycle_per_myriad =
 			100 * CVT_C_PRIME - (CVT_M_PRIME * 100000) / hfreq;
 		int h_blank;

 		if (ideal_duty_cycle_per_myriad < 2000)
 			ideal_duty_cycle_per_myriad = 2000;

 		h_blank = image_width * ideal_duty_cycle_per_myriad /
 					(10000 - ideal_duty_cycle_per_myriad);
 		h_blank = (h_blank / (2 * CVT_CELL_GRAN)) * 2 * CVT_CELL_GRAN;

 		pix_clk = (image_width + h_blank) * hfreq;
 		pix_clk = (pix_clk / CVT_PXL_CLK_GRAN) * CVT_PXL_CLK_GRAN;

 		h_bp = h_blank / 2;
 		frame_width = image_width + h_blank;

 		hsync = (frame_width * 8 + 50) / 100;
 		hsync = hsync - hsync % CVT_CELL_GRAN;
 		h_fp = h_blank - hsync - h_bp;
 	}

 	fmt->type = V4L2_DV_BT_656_1120;
 	fmt->bt.polarities = polarities;
 	fmt->bt.width = image_width;
 	fmt->bt.height = image_height;
 	fmt->bt.hfrontporch = h_fp;
 	fmt->bt.vfrontporch = v_fp;
 	fmt->bt.hsync = hsync;
 	fmt->bt.vsync = vsync;
 	fmt->bt.hbackporch = frame_width - image_width - h_fp - hsync;
 	fmt->bt.vbackporch = frame_height - image_height - v_fp - vsync;
 	fmt->bt.pixelclock = pix_clk;
 	fmt->bt.standards = V4L2_DV_BT_STD_CVT;
 	if (reduced_blanking)
 		fmt->bt.flags |= V4L2_DV_FL_REDUCED_BLANKING;
 	return true;
 }
 EXPORT_SYMBOL_GPL(v4l2_detect_cvt);

 /*
  * GTF defines
  * Based on Generalized Timing Formula Standard
  * Version 1.1 September 2, 1999
  */

 #define GTF_PXL_CLK_GRAN	250000	/* pixel clock granularity */

 #define GTF_MIN_VSYNC_BP	550	/* min time of vsync + back porch (us) */
 #define GTF_V_FP		1	/* vertical front porch (lines) */
 #define GTF_CELL_GRAN		8	/* character cell granularity */

 /* Default */
 #define GTF_D_M			600	/* blanking formula gradient */
 #define GTF_D_C			40	/* blanking formula offset */
 #define GTF_D_K			128	/* blanking formula scaling factor */
 #define GTF_D_J			20	/* blanking formula scaling factor */
 #define GTF_D_C_PRIME ((((GTF_D_C - GTF_D_J) * GTF_D_K) / 256) + GTF_D_J)
 #define GTF_D_M_PRIME ((GTF_D_K * GTF_D_M) / 256)

 /* Secondary */
 #define GTF_S_M			3600	/* blanking formula gradient */
 #define GTF_S_C			40	/* blanking formula offset */
 #define GTF_S_K			128	/* blanking formula scaling factor */
 #define GTF_S_J			35	/* blanking formula scaling factor */
 #define GTF_S_C_PRIME ((((GTF_S_C - GTF_S_J) * GTF_S_K) / 256) + GTF_S_J)
 #define GTF_S_M_PRIME ((GTF_S_K * GTF_S_M) / 256)

 /** v4l2_detect_gtf - detect if the given timings follow the GTF standard
  * @frame_height - the total height of the frame (including blanking) in lines.
  * @hfreq - the horizontal frequency in Hz.
  * @vsync - the height of the vertical sync in lines.
  * @polarities - the horizontal and vertical polarities (same as struct
  *		v4l2_bt_timings polarities).
  * @aspect - preferred aspect ratio. GTF has no method of determining the
  *		aspect ratio in order to derive the image width from the
  *		image height, so it has to be passed explicitly. Usually
  *		the native screen aspect ratio is used for this. If it
  *		is not filled in correctly, then 16:9 will be assumed.
  * @fmt - the resulting timings.
  *
  * This function will attempt to detect if the given values correspond to a
  * valid GTF format. If so, then it will return true, and fmt will be filled
  * in with the found GTF timings.
  */
 bool v4l2_detect_gtf(unsigned frame_height,
 		unsigned hfreq,
 		unsigned vsync,
 		u32 polarities,
 		struct v4l2_fract aspect,
 		struct v4l2_dv_timings *fmt)
 {
 	int pix_clk;
 	int  v_fp, v_bp, h_fp, hsync;
 	int frame_width, image_height, image_width;
 	bool default_gtf;
 	int h_blank;

 	if (vsync != 3)
 		return false;

 	if (polarities == V4L2_DV_VSYNC_POS_POL)
 		default_gtf = true;
 	else if (polarities == V4L2_DV_HSYNC_POS_POL)
 		default_gtf = false;
 	else
 		return false;

 	/* Vertical */
 	v_fp = GTF_V_FP;
 	v_bp = (GTF_MIN_VSYNC_BP * hfreq + 999999) / 1000000 - vsync;
 	image_height = (frame_height - v_fp - vsync - v_bp + 1) & ~0x1;

 	if (aspect.numerator == 0 || aspect.denominator == 0) {
 		aspect.numerator = 16;
 		aspect.denominator = 9;
 	}
 	image_width = ((image_height * aspect.numerator) / aspect.denominator);
 	image_width = (image_width + GTF_CELL_GRAN/2) & ~(GTF_CELL_GRAN - 1);

 	/* Horizontal */
 	if (default_gtf)
 		h_blank = ((image_width * GTF_D_C_PRIME * hfreq) -
 					(image_width * GTF_D_M_PRIME * 1000) +
 			(hfreq * (100 - GTF_D_C_PRIME) + GTF_D_M_PRIME * 1000) / 2) /
 			(hfreq * (100 - GTF_D_C_PRIME) + GTF_D_M_PRIME * 1000);
 	else
 		h_blank = ((image_width * GTF_S_C_PRIME * hfreq) -
 					(image_width * GTF_S_M_PRIME * 1000) +
 			(hfreq * (100 - GTF_S_C_PRIME) + GTF_S_M_PRIME * 1000) / 2) /
 			(hfreq * (100 - GTF_S_C_PRIME) + GTF_S_M_PRIME * 1000);

 	h_blank = h_blank - h_blank % (2 * GTF_CELL_GRAN);
 	frame_width = image_width + h_blank;

 	pix_clk = (image_width + h_blank) * hfreq;
 	pix_clk = pix_clk / GTF_PXL_CLK_GRAN * GTF_PXL_CLK_GRAN;

 	hsync = (frame_width * 8 + 50) / 100;
 	hsync = hsync - hsync % GTF_CELL_GRAN;

 	h_fp = h_blank / 2 - hsync;

 	fmt->type = V4L2_DV_BT_656_1120;
 	fmt->bt.polarities = polarities;
 	fmt->bt.width = image_width;
 	fmt->bt.height = image_height;
 	fmt->bt.hfrontporch = h_fp;
 	fmt->bt.vfrontporch = v_fp;
 	fmt->bt.hsync = hsync;
 	fmt->bt.vsync = vsync;
 	fmt->bt.hbackporch = frame_width - image_width - h_fp - hsync;
 	fmt->bt.vbackporch = frame_height - image_height - v_fp - vsync;
 	fmt->bt.pixelclock = pix_clk;
 	fmt->bt.standards = V4L2_DV_BT_STD_GTF;
 	if (!default_gtf)
 		fmt->bt.flags |= V4L2_DV_FL_REDUCED_BLANKING;
 	return true;
 }
 EXPORT_SYMBOL_GPL(v4l2_detect_gtf);

 /** v4l2_calc_aspect_ratio - calculate the aspect ratio based on bytes
  *	0x15 and 0x16 from the EDID.
  * @hor_landscape - byte 0x15 from the EDID.
  * @vert_portrait - byte 0x16 from the EDID.
  *
  * Determines the aspect ratio from the EDID.
  * See VESA Enhanced EDID standard, release A, rev 2, section 3.6.2:
  * "Horizontal and Vertical Screen Size or Aspect Ratio"
  */
 struct v4l2_fract v4l2_calc_aspect_ratio(u8 hor_landscape, u8 vert_portrait)
 {
 	struct v4l2_fract aspect = { 16, 9 };
 	u32 tmp;
 	u8 ratio;

 	/* Nothing filled in, fallback to 16:9 */
 	if (!hor_landscape && !vert_portrait)
 		return aspect;
 	/* Both filled in, so they are interpreted as the screen size in cm */
 	if (hor_landscape && vert_portrait) {
 		aspect.numerator = hor_landscape;
 		aspect.denominator = vert_portrait;
 		return aspect;
 	}
 	/* Only one is filled in, so interpret them as a ratio:
 	   (val + 99) / 100 */
 	ratio = hor_landscape | vert_portrait;
 	/* Change some rounded values into the exact aspect ratio */
 	if (ratio == 79) {
 		aspect.numerator = 16;
 		aspect.denominator = 9;
 	} else if (ratio == 34) {
 		aspect.numerator = 4;
 		aspect.denominator = 3;
 	} else if (ratio == 68) {
 		aspect.numerator = 15;
 		aspect.denominator = 9;
 	} else {
 		aspect.numerator = hor_landscape + 99;
 		aspect.denominator = 100;
 	}
 	if (hor_landscape)
 		return aspect;
 	/* The aspect ratio is for portrait, so swap numerator and denominator */
 	tmp = aspect.denominator;
 	aspect.denominator = aspect.numerator;
 	aspect.numerator = tmp;
 	return aspect;
 }
 EXPORT_SYMBOL_GPL(v4l2_calc_aspect_ratio);
	/*
	* v4l2-dv-timings - dv-timings helper functions
	*
	* Copyright 2013 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
	*
	* This program is free software; you may redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; version 2 of the License.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
	* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
	* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
	* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
	* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
	* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
	* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
	* SOFTWARE.
	*
	*/

	#include <linux/module.h>
	#include <linux/types.h>
	#include <linux/kernel.h>
	#include <linux/errno.h>
	#include <linux/videodev2.h>
	#include <linux/v4l2-dv-timings.h>
	#include <media/v4l2-dv-timings.h>

	MODULE_AUTHOR("Hans Verkuil");
	MODULE_DESCRIPTION("V4L2 DV Timings Helper Functions");
	MODULE_LICENSE("GPL");

	const struct v4l2_dv_timings v4l2_dv_timings_presets[] = {
	V4L2_DV_BT_CEA_640X480P59_94,
	V4L2_DV_BT_CEA_720X480I59_94,
	V4L2_DV_BT_CEA_720X480P59_94,
	V4L2_DV_BT_CEA_720X576I50,
	V4L2_DV_BT_CEA_720X576P50,
	V4L2_DV_BT_CEA_1280X720P24,
	V4L2_DV_BT_CEA_1280X720P25,
	V4L2_DV_BT_CEA_1280X720P30,
	V4L2_DV_BT_CEA_1280X720P50,
	V4L2_DV_BT_CEA_1280X720P60,
	V4L2_DV_BT_CEA_1920X1080P24,
	V4L2_DV_BT_CEA_1920X1080P25,
	V4L2_DV_BT_CEA_1920X1080P30,
	V4L2_DV_BT_CEA_1920X1080I50,
	V4L2_DV_BT_CEA_1920X1080P50,
	V4L2_DV_BT_CEA_1920X1080I60,
	V4L2_DV_BT_CEA_1920X1080P60,
	V4L2_DV_BT_DMT_640X350P85,
	V4L2_DV_BT_DMT_640X400P85,
	V4L2_DV_BT_DMT_720X400P85,
	V4L2_DV_BT_DMT_640X480P72,
	V4L2_DV_BT_DMT_640X480P75,
	V4L2_DV_BT_DMT_640X480P85,
	V4L2_DV_BT_DMT_800X600P56,
	V4L2_DV_BT_DMT_800X600P60,
	V4L2_DV_BT_DMT_800X600P72,
	V4L2_DV_BT_DMT_800X600P75,
	V4L2_DV_BT_DMT_800X600P85,
	V4L2_DV_BT_DMT_800X600P120_RB,
	V4L2_DV_BT_DMT_848X480P60,
	V4L2_DV_BT_DMT_1024X768I43,
	V4L2_DV_BT_DMT_1024X768P60,
	V4L2_DV_BT_DMT_1024X768P70,
	V4L2_DV_BT_DMT_1024X768P75,
	V4L2_DV_BT_DMT_1024X768P85,
	V4L2_DV_BT_DMT_1024X768P120_RB,
	V4L2_DV_BT_DMT_1152X864P75,
	V4L2_DV_BT_DMT_1280X768P60_RB,
	V4L2_DV_BT_DMT_1280X768P60,
	V4L2_DV_BT_DMT_1280X768P75,
	V4L2_DV_BT_DMT_1280X768P85,
	V4L2_DV_BT_DMT_1280X768P120_RB,
	V4L2_DV_BT_DMT_1280X800P60_RB,
	V4L2_DV_BT_DMT_1280X800P60,
	V4L2_DV_BT_DMT_1280X800P75,
	V4L2_DV_BT_DMT_1280X800P85,
	V4L2_DV_BT_DMT_1280X800P120_RB,
	V4L2_DV_BT_DMT_1280X960P60,
	V4L2_DV_BT_DMT_1280X960P85,
	V4L2_DV_BT_DMT_1280X960P120_RB,
	V4L2_DV_BT_DMT_1280X1024P60,
	V4L2_DV_BT_DMT_1280X1024P75,
	V4L2_DV_BT_DMT_1280X1024P85,
	V4L2_DV_BT_DMT_1280X1024P120_RB,
	V4L2_DV_BT_DMT_1360X768P60,
	V4L2_DV_BT_DMT_1360X768P120_RB,
	V4L2_DV_BT_DMT_1366X768P60,
	V4L2_DV_BT_DMT_1366X768P60_RB,
	V4L2_DV_BT_DMT_1400X1050P60_RB,
	V4L2_DV_BT_DMT_1400X1050P60,
	V4L2_DV_BT_DMT_1400X1050P75,
	V4L2_DV_BT_DMT_1400X1050P85,
	V4L2_DV_BT_DMT_1400X1050P120_RB,
	V4L2_DV_BT_DMT_1440X900P60_RB,
	V4L2_DV_BT_DMT_1440X900P60,
	V4L2_DV_BT_DMT_1440X900P75,
	V4L2_DV_BT_DMT_1440X900P85,
	V4L2_DV_BT_DMT_1440X900P120_RB,
	V4L2_DV_BT_DMT_1600X900P60_RB,
	V4L2_DV_BT_DMT_1600X1200P60,
	V4L2_DV_BT_DMT_1600X1200P65,
	V4L2_DV_BT_DMT_1600X1200P70,
	V4L2_DV_BT_DMT_1600X1200P75,
	V4L2_DV_BT_DMT_1600X1200P85,
	V4L2_DV_BT_DMT_1600X1200P120_RB,
	V4L2_DV_BT_DMT_1680X1050P60_RB,
	V4L2_DV_BT_DMT_1680X1050P60,
	V4L2_DV_BT_DMT_1680X1050P75,
	V4L2_DV_BT_DMT_1680X1050P85,
	V4L2_DV_BT_DMT_1680X1050P120_RB,
	V4L2_DV_BT_DMT_1792X1344P60,
	V4L2_DV_BT_DMT_1792X1344P75,
	V4L2_DV_BT_DMT_1792X1344P120_RB,
	V4L2_DV_BT_DMT_1856X1392P60,
	V4L2_DV_BT_DMT_1856X1392P75,
	V4L2_DV_BT_DMT_1856X1392P120_RB,
	V4L2_DV_BT_DMT_1920X1200P60_RB,
	V4L2_DV_BT_DMT_1920X1200P60,
	V4L2_DV_BT_DMT_1920X1200P75,
	V4L2_DV_BT_DMT_1920X1200P85,
	V4L2_DV_BT_DMT_1920X1200P120_RB,
	V4L2_DV_BT_DMT_1920X1440P60,
	V4L2_DV_BT_DMT_1920X1440P75,
	V4L2_DV_BT_DMT_1920X1440P120_RB,
	V4L2_DV_BT_DMT_2048X1152P60_RB,
	V4L2_DV_BT_DMT_2560X1600P60_RB,
	V4L2_DV_BT_DMT_2560X1600P60,
	V4L2_DV_BT_DMT_2560X1600P75,
	V4L2_DV_BT_DMT_2560X1600P85,
	V4L2_DV_BT_DMT_2560X1600P120_RB,
	V4L2_DV_BT_CEA_3840X2160P24,
	V4L2_DV_BT_CEA_3840X2160P25,
	V4L2_DV_BT_CEA_3840X2160P30,
	V4L2_DV_BT_CEA_3840X2160P50,
	V4L2_DV_BT_CEA_3840X2160P60,
	V4L2_DV_BT_CEA_4096X2160P24,
	V4L2_DV_BT_CEA_4096X2160P25,
	V4L2_DV_BT_CEA_4096X2160P30,
	V4L2_DV_BT_CEA_4096X2160P50,
	V4L2_DV_BT_DMT_4096X2160P59_94_RB,
	V4L2_DV_BT_CEA_4096X2160P60,
	{ }
	};
	EXPORT_SYMBOL_GPL(v4l2_dv_timings_presets);

	bool v4l2_valid_dv_timings(const struct v4l2_dv_timings *t,
	const struct v4l2_dv_timings_cap *dvcap,
	v4l2_check_dv_timings_fnc fnc,
	void *fnc_handle)
	{
	const struct v4l2_bt_timings *bt = &t->bt;
	const struct v4l2_bt_timings_cap *cap = &dvcap->bt;
	u32 caps = cap->capabilities;

	if (t->type != V4L2_DV_BT_656_1120)
	return false;
	if (t->type != dvcap->type \|\|
	bt->height < cap->min_height \|\|
	bt->height > cap->max_height \|\|
	bt->width < cap->min_width \|\|
	bt->width > cap->max_width \|\|
	bt->pixelclock < cap->min_pixelclock \|\|
	bt->pixelclock > cap->max_pixelclock \|\|
	(cap->standards && bt->standards &&
	!(bt->standards & cap->standards)) \|\|
	(bt->interlaced && !(caps & V4L2_DV_BT_CAP_INTERLACED)) \|\|
	(!bt->interlaced && !(caps & V4L2_DV_BT_CAP_PROGRESSIVE)))
	return false;
	return fnc == NULL \|\| fnc(t, fnc_handle);
	}
	EXPORT_SYMBOL_GPL(v4l2_valid_dv_timings);

	int v4l2_enum_dv_timings_cap(struct v4l2_enum_dv_timings *t,
	const struct v4l2_dv_timings_cap *cap,
	v4l2_check_dv_timings_fnc fnc,
	void *fnc_handle)
	{
	u32 i, idx;

	memset(t->reserved, 0, sizeof(t->reserved));
	for (i = idx = 0; v4l2_dv_timings_presets[i].bt.width; i++) {
	if (v4l2_valid_dv_timings(v4l2_dv_timings_presets + i, cap,
	fnc, fnc_handle) &&
	idx++ == t->index) {
	t->timings = v4l2_dv_timings_presets[i];
	return 0;
	}
	}
	return -EINVAL;
	}
	EXPORT_SYMBOL_GPL(v4l2_enum_dv_timings_cap);

	bool v4l2_find_dv_timings_cap(struct v4l2_dv_timings *t,
	const struct v4l2_dv_timings_cap *cap,
	unsigned pclock_delta,
	v4l2_check_dv_timings_fnc fnc,
	void *fnc_handle)
	{
	int i;

	if (!v4l2_valid_dv_timings(t, cap, fnc, fnc_handle))
	return false;

	for (i = 0; i < v4l2_dv_timings_presets[i].bt.width; i++) {
	if (v4l2_valid_dv_timings(v4l2_dv_timings_presets + i, cap,
	fnc, fnc_handle) &&
	v4l2_match_dv_timings(t, v4l2_dv_timings_presets + i,
	pclock_delta)) {
	*t = v4l2_dv_timings_presets[i];
	return true;
	}
	}
	return false;
	}
	EXPORT_SYMBOL_GPL(v4l2_find_dv_timings_cap);

	/**
	* v4l2_match_dv_timings - check if two timings match
	* @t1 - compare this v4l2_dv_timings struct...
	* @t2 - with this struct.
	* @pclock_delta - the allowed pixelclock deviation.
	*
	* Compare t1 with t2 with a given margin of error for the pixelclock.
	*/
	bool v4l2_match_dv_timings(const struct v4l2_dv_timings *t1,
	const struct v4l2_dv_timings *t2,
	unsigned pclock_delta)
	{
	if (t1->type != t2->type \|\| t1->type != V4L2_DV_BT_656_1120)
	return false;
	if (t1->bt.width == t2->bt.width &&
	t1->bt.height == t2->bt.height &&
	t1->bt.interlaced == t2->bt.interlaced &&
	t1->bt.polarities == t2->bt.polarities &&
	t1->bt.pixelclock >= t2->bt.pixelclock - pclock_delta &&
	t1->bt.pixelclock <= t2->bt.pixelclock + pclock_delta &&
	t1->bt.hfrontporch == t2->bt.hfrontporch &&
	t1->bt.vfrontporch == t2->bt.vfrontporch &&
	t1->bt.vsync == t2->bt.vsync &&
	t1->bt.vbackporch == t2->bt.vbackporch &&
	(!t1->bt.interlaced \|\|
	(t1->bt.il_vfrontporch == t2->bt.il_vfrontporch &&
	t1->bt.il_vsync == t2->bt.il_vsync &&
	t1->bt.il_vbackporch == t2->bt.il_vbackporch)))
	return true;
	return false;
	}
	EXPORT_SYMBOL_GPL(v4l2_match_dv_timings);

	void v4l2_print_dv_timings(const char dev_prefix, const char prefix,
	const struct v4l2_dv_timings *t, bool detailed)
	{
	const struct v4l2_bt_timings *bt = &t->bt;
	u32 htot, vtot;

	if (t->type != V4L2_DV_BT_656_1120)
	return;

	htot = V4L2_DV_BT_FRAME_WIDTH(bt);
	vtot = V4L2_DV_BT_FRAME_HEIGHT(bt);

	if (prefix == NULL)
	prefix = "";

	pr_info("%s: %s%ux%u%s%u (%ux%u)\n", dev_prefix, prefix,
	bt->width, bt->height, bt->interlaced ? "i" : "p",
	(htot * vtot) > 0 ? ((u32)bt->pixelclock / (htot * vtot)) : 0,
	htot, vtot);

	if (!detailed)
	return;

	pr_info("%s: horizontal: fp = %u, %ssync = %u, bp = %u\n",
	dev_prefix, bt->hfrontporch,
	(bt->polarities & V4L2_DV_HSYNC_POS_POL) ? "+" : "-",
	bt->hsync, bt->hbackporch);
	pr_info("%s: vertical: fp = %u, %ssync = %u, bp = %u\n",
	dev_prefix, bt->vfrontporch,
	(bt->polarities & V4L2_DV_VSYNC_POS_POL) ? "+" : "-",
	bt->vsync, bt->vbackporch);
	pr_info("%s: pixelclock: %llu\n", dev_prefix, bt->pixelclock);
	pr_info("%s: flags (0x%x):%s%s%s%s\n", dev_prefix, bt->flags,
	(bt->flags & V4L2_DV_FL_REDUCED_BLANKING) ?
	" REDUCED_BLANKING" : "",
	(bt->flags & V4L2_DV_FL_CAN_REDUCE_FPS) ?
	" CAN_REDUCE_FPS" : "",
	(bt->flags & V4L2_DV_FL_REDUCED_FPS) ?
	" REDUCED_FPS" : "",
	(bt->flags & V4L2_DV_FL_HALF_LINE) ?
	" HALF_LINE" : "");
	pr_info("%s: standards (0x%x):%s%s%s%s\n", dev_prefix, bt->standards,
	(bt->standards & V4L2_DV_BT_STD_CEA861) ? " CEA" : "",
	(bt->standards & V4L2_DV_BT_STD_DMT) ? " DMT" : "",
	(bt->standards & V4L2_DV_BT_STD_CVT) ? " CVT" : "",
	(bt->standards & V4L2_DV_BT_STD_GTF) ? " GTF" : "");
	}
	EXPORT_SYMBOL_GPL(v4l2_print_dv_timings);

	/*
	* CVT defines
	* Based on Coordinated Video Timings Standard
	* version 1.1 September 10, 2003
	*/

	#define CVT_PXL_CLK_GRAN 250000 /* pixel clock granularity */

	/* Normal blanking */
	#define CVT_MIN_V_BPORCH 7 /* lines */
	#define CVT_MIN_V_PORCH_RND 3 /* lines */
	#define CVT_MIN_VSYNC_BP 550 /* min time of vsync + back porch (us) */

	/* Normal blanking for CVT uses GTF to calculate horizontal blanking */
	#define CVT_CELL_GRAN 8 /* character cell granularity */
	#define CVT_M 600 /* blanking formula gradient */
	#define CVT_C 40 /* blanking formula offset */
	#define CVT_K 128 /* blanking formula scaling factor */
	#define CVT_J 20 /* blanking formula scaling factor */
	#define CVT_C_PRIME (((CVT_C - CVT_J) * CVT_K / 256) + CVT_J)
	#define CVT_M_PRIME (CVT_K * CVT_M / 256)

	/* Reduced Blanking */
	#define CVT_RB_MIN_V_BPORCH 7 /* lines */
	#define CVT_RB_V_FPORCH 3 /* lines */
	#define CVT_RB_MIN_V_BLANK 460 /* us */
	#define CVT_RB_H_SYNC 32 /* pixels */
	#define CVT_RB_H_BPORCH 80 /* pixels */
	#define CVT_RB_H_BLANK 160 /* pixels */

	/** v4l2_detect_cvt - detect if the given timings follow the CVT standard
	* @frame_height - the total height of the frame (including blanking) in lines.
	* @hfreq - the horizontal frequency in Hz.
	* @vsync - the height of the vertical sync in lines.
	* @polarities - the horizontal and vertical polarities (same as struct
	* v4l2_bt_timings polarities).
	* @fmt - the resulting timings.
	*
	* This function will attempt to detect if the given values correspond to a
	* valid CVT format. If so, then it will return true, and fmt will be filled
	* in with the found CVT timings.
	*
	* TODO: VESA defined a new version 2 of their reduced blanking
	* formula. Support for that is currently missing in this CVT
	* detection function.
	*/
	bool v4l2_detect_cvt(unsigned frame_height, unsigned hfreq, unsigned vsync,
	u32 polarities, struct v4l2_dv_timings *fmt)
	{
	int v_fp, v_bp, h_fp, h_bp, hsync;
	int frame_width, image_height, image_width;
	bool reduced_blanking;
	unsigned pix_clk;

	if (vsync < 4 \|\| vsync > 7)
	return false;

	if (polarities == V4L2_DV_VSYNC_POS_POL)
	reduced_blanking = false;
	else if (polarities == V4L2_DV_HSYNC_POS_POL)
	reduced_blanking = true;
	else
	return false;

	/* Vertical */
	if (reduced_blanking) {
	v_fp = CVT_RB_V_FPORCH;
	v_bp = (CVT_RB_MIN_V_BLANK * hfreq + 1999999) / 1000000;
	v_bp -= vsync + v_fp;

	if (v_bp < CVT_RB_MIN_V_BPORCH)
	v_bp = CVT_RB_MIN_V_BPORCH;
	} else {
	v_fp = CVT_MIN_V_PORCH_RND;
	v_bp = (CVT_MIN_VSYNC_BP * hfreq + 1999999) / 1000000 - vsync;

	if (v_bp < CVT_MIN_V_BPORCH)
	v_bp = CVT_MIN_V_BPORCH;
	}
	image_height = (frame_height - v_fp - vsync - v_bp + 1) & ~0x1;

	/* Aspect ratio based on vsync */
	switch (vsync) {
	case 4:
	image_width = (image_height * 4) / 3;
	break;
	case 5:
	image_width = (image_height * 16) / 9;
	break;
	case 6:
	image_width = (image_height * 16) / 10;
	break;
	case 7:
	/* special case */
	if (image_height == 1024)
	image_width = (image_height * 5) / 4;
	else if (image_height == 768)
	image_width = (image_height * 15) / 9;
	else
	return false;
	break;
	default:
	return false;
	}

	image_width = image_width & ~7;

	/* Horizontal */
	if (reduced_blanking) {
	pix_clk = (image_width + CVT_RB_H_BLANK) * hfreq;
	pix_clk = (pix_clk / CVT_PXL_CLK_GRAN) * CVT_PXL_CLK_GRAN;

	h_bp = CVT_RB_H_BPORCH;
	hsync = CVT_RB_H_SYNC;
	h_fp = CVT_RB_H_BLANK - h_bp - hsync;

	frame_width = image_width + CVT_RB_H_BLANK;
	} else {
	unsigned ideal_duty_cycle_per_myriad =
	100 * CVT_C_PRIME - (CVT_M_PRIME * 100000) / hfreq;
	int h_blank;

	if (ideal_duty_cycle_per_myriad < 2000)
	ideal_duty_cycle_per_myriad = 2000;

	h_blank = image_width * ideal_duty_cycle_per_myriad /
	(10000 - ideal_duty_cycle_per_myriad);
	h_blank = (h_blank / (2 * CVT_CELL_GRAN)) * 2 * CVT_CELL_GRAN;

	pix_clk = (image_width + h_blank) * hfreq;
	pix_clk = (pix_clk / CVT_PXL_CLK_GRAN) * CVT_PXL_CLK_GRAN;

	h_bp = h_blank / 2;
	frame_width = image_width + h_blank;

	hsync = (frame_width * 8 + 50) / 100;
	hsync = hsync - hsync % CVT_CELL_GRAN;
	h_fp = h_blank - hsync - h_bp;
	}

	fmt->type = V4L2_DV_BT_656_1120;
	fmt->bt.polarities = polarities;
	fmt->bt.width = image_width;
	fmt->bt.height = image_height;
	fmt->bt.hfrontporch = h_fp;
	fmt->bt.vfrontporch = v_fp;
	fmt->bt.hsync = hsync;
	fmt->bt.vsync = vsync;
	fmt->bt.hbackporch = frame_width - image_width - h_fp - hsync;
	fmt->bt.vbackporch = frame_height - image_height - v_fp - vsync;
	fmt->bt.pixelclock = pix_clk;
	fmt->bt.standards = V4L2_DV_BT_STD_CVT;
	if (reduced_blanking)
	fmt->bt.flags \|= V4L2_DV_FL_REDUCED_BLANKING;
	return true;
	}
	EXPORT_SYMBOL_GPL(v4l2_detect_cvt);

	/*
	* GTF defines
	* Based on Generalized Timing Formula Standard
	* Version 1.1 September 2, 1999
	*/

	#define GTF_PXL_CLK_GRAN 250000 /* pixel clock granularity */

	#define GTF_MIN_VSYNC_BP 550 /* min time of vsync + back porch (us) */
	#define GTF_V_FP 1 /* vertical front porch (lines) */
	#define GTF_CELL_GRAN 8 /* character cell granularity */

	/* Default */
	#define GTF_D_M 600 /* blanking formula gradient */
	#define GTF_D_C 40 /* blanking formula offset */
	#define GTF_D_K 128 /* blanking formula scaling factor */
	#define GTF_D_J 20 /* blanking formula scaling factor */
	#define GTF_D_C_PRIME ((((GTF_D_C - GTF_D_J) * GTF_D_K) / 256) + GTF_D_J)
	#define GTF_D_M_PRIME ((GTF_D_K * GTF_D_M) / 256)

	/* Secondary */
	#define GTF_S_M 3600 /* blanking formula gradient */
	#define GTF_S_C 40 /* blanking formula offset */
	#define GTF_S_K 128 /* blanking formula scaling factor */
	#define GTF_S_J 35 /* blanking formula scaling factor */
	#define GTF_S_C_PRIME ((((GTF_S_C - GTF_S_J) * GTF_S_K) / 256) + GTF_S_J)
	#define GTF_S_M_PRIME ((GTF_S_K * GTF_S_M) / 256)

	/** v4l2_detect_gtf - detect if the given timings follow the GTF standard
	* @frame_height - the total height of the frame (including blanking) in lines.
	* @hfreq - the horizontal frequency in Hz.
	* @vsync - the height of the vertical sync in lines.
	* @polarities - the horizontal and vertical polarities (same as struct
	* v4l2_bt_timings polarities).
	* @aspect - preferred aspect ratio. GTF has no method of determining the
	* aspect ratio in order to derive the image width from the
	* image height, so it has to be passed explicitly. Usually
	* the native screen aspect ratio is used for this. If it
	* is not filled in correctly, then 16:9 will be assumed.
	* @fmt - the resulting timings.
	*
	* This function will attempt to detect if the given values correspond to a
	* valid GTF format. If so, then it will return true, and fmt will be filled
	* in with the found GTF timings.
	*/
	bool v4l2_detect_gtf(unsigned frame_height,
	unsigned hfreq,
	unsigned vsync,
	u32 polarities,
	struct v4l2_fract aspect,
	struct v4l2_dv_timings *fmt)
	{
	int pix_clk;
	int v_fp, v_bp, h_fp, hsync;
	int frame_width, image_height, image_width;
	bool default_gtf;
	int h_blank;

	if (vsync != 3)
	return false;

	if (polarities == V4L2_DV_VSYNC_POS_POL)
	default_gtf = true;
	else if (polarities == V4L2_DV_HSYNC_POS_POL)
	default_gtf = false;
	else
	return false;

	/* Vertical */
	v_fp = GTF_V_FP;
	v_bp = (GTF_MIN_VSYNC_BP * hfreq + 999999) / 1000000 - vsync;
	image_height = (frame_height - v_fp - vsync - v_bp + 1) & ~0x1;

	if (aspect.numerator == 0 \|\| aspect.denominator == 0) {
	aspect.numerator = 16;
	aspect.denominator = 9;
	}
	image_width = ((image_height * aspect.numerator) / aspect.denominator);
	image_width = (image_width + GTF_CELL_GRAN/2) & ~(GTF_CELL_GRAN - 1);

	/* Horizontal */
	if (default_gtf)
	h_blank = ((image_width * GTF_D_C_PRIME * hfreq) -
	(image_width * GTF_D_M_PRIME * 1000) +
	(hfreq * (100 - GTF_D_C_PRIME) + GTF_D_M_PRIME * 1000) / 2) /
	(hfreq * (100 - GTF_D_C_PRIME) + GTF_D_M_PRIME * 1000);
	else
	h_blank = ((image_width * GTF_S_C_PRIME * hfreq) -
	(image_width * GTF_S_M_PRIME * 1000) +
	(hfreq * (100 - GTF_S_C_PRIME) + GTF_S_M_PRIME * 1000) / 2) /
	(hfreq * (100 - GTF_S_C_PRIME) + GTF_S_M_PRIME * 1000);

	h_blank = h_blank - h_blank % (2 * GTF_CELL_GRAN);
	frame_width = image_width + h_blank;

	pix_clk = (image_width + h_blank) * hfreq;
	pix_clk = pix_clk / GTF_PXL_CLK_GRAN * GTF_PXL_CLK_GRAN;

	hsync = (frame_width * 8 + 50) / 100;
	hsync = hsync - hsync % GTF_CELL_GRAN;

	h_fp = h_blank / 2 - hsync;

	fmt->type = V4L2_DV_BT_656_1120;
	fmt->bt.polarities = polarities;
	fmt->bt.width = image_width;
	fmt->bt.height = image_height;
	fmt->bt.hfrontporch = h_fp;
	fmt->bt.vfrontporch = v_fp;
	fmt->bt.hsync = hsync;
	fmt->bt.vsync = vsync;
	fmt->bt.hbackporch = frame_width - image_width - h_fp - hsync;
	fmt->bt.vbackporch = frame_height - image_height - v_fp - vsync;
	fmt->bt.pixelclock = pix_clk;
	fmt->bt.standards = V4L2_DV_BT_STD_GTF;
	if (!default_gtf)
	fmt->bt.flags \|= V4L2_DV_FL_REDUCED_BLANKING;
	return true;
	}
	EXPORT_SYMBOL_GPL(v4l2_detect_gtf);

	/** v4l2_calc_aspect_ratio - calculate the aspect ratio based on bytes
	* 0x15 and 0x16 from the EDID.
	* @hor_landscape - byte 0x15 from the EDID.
	* @vert_portrait - byte 0x16 from the EDID.
	*
	* Determines the aspect ratio from the EDID.
	* See VESA Enhanced EDID standard, release A, rev 2, section 3.6.2:
	* "Horizontal and Vertical Screen Size or Aspect Ratio"
	*/
	struct v4l2_fract v4l2_calc_aspect_ratio(u8 hor_landscape, u8 vert_portrait)
	{
	struct v4l2_fract aspect = { 16, 9 };
	u32 tmp;
	u8 ratio;

	/* Nothing filled in, fallback to 16:9 */
	if (!hor_landscape && !vert_portrait)
	return aspect;
	/* Both filled in, so they are interpreted as the screen size in cm */
	if (hor_landscape && vert_portrait) {
	aspect.numerator = hor_landscape;
	aspect.denominator = vert_portrait;
	return aspect;
	}
	/* Only one is filled in, so interpret them as a ratio:
	(val + 99) / 100 */
	ratio = hor_landscape \| vert_portrait;
	/* Change some rounded values into the exact aspect ratio */
	if (ratio == 79) {
	aspect.numerator = 16;
	aspect.denominator = 9;
	} else if (ratio == 34) {
	aspect.numerator = 4;
	aspect.denominator = 3;
	} else if (ratio == 68) {
	aspect.numerator = 15;
	aspect.denominator = 9;
	} else {
	aspect.numerator = hor_landscape + 99;
	aspect.denominator = 100;
	}
	if (hor_landscape)
	return aspect;
	/* The aspect ratio is for portrait, so swap numerator and denominator */
	tmp = aspect.denominator;
	aspect.denominator = aspect.numerator;
	aspect.numerator = tmp;
	return aspect;
	}
	EXPORT_SYMBOL_GPL(v4l2_calc_aspect_ratio);