utils/v4l2-ctl/v4l2-ctl-modes.cpp

// SPDX-License-Identifier: GPL-2.0-only
/*
 * v4l2-ctl-modes.cpp - functions to calculate cvt and gtf mode timings.
 *
 * Copyright 2015 Cisco Systems, Inc. and/or its affiliates. All rights
 * reserved.
 */

#include "v4l2-ctl.h"

static bool valid_params(int width, int height, int refresh_rate)
{
	if (width <= 0) {
		fprintf(stderr, "Invalid value %d for width\n", width);
		return false;
	}

	if (height <= 0) {
		fprintf(stderr, "Invalid value %d for height\n", height);
		return false;
	}

	if (refresh_rate <= 0) {
		fprintf(stderr, "Invalid value %d for refresh rate\n",
				refresh_rate);
		return false;
	}
	return true;
}

#define HV_FACTOR		(1000)
#define CVT_MARGIN_PERCENT	  (18)
#define CVT_HSYNC_PERCENT	   (8)

/*
 * CVT defines Based on
 * Coordinated Video Timings Standard Ver 1.2 Feb 08, 2013
 */

#define CVT_PXL_CLK_GRAN    (250000)  /* pixel clock granularity */
#define CVT_PXL_CLK_GRAN_RB_V2 (1000)	/* granularity for reduced blanking v2*/

/* Normal blanking */
#define CVT_MIN_V_BPORCH     (7)  /* lines */
#define CVT_MIN_V_PORCH_RND  (3)  /* lines */
#define CVT_MIN_VSYNC_BP    (550) /* time v_sync + 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 scale factor */
#define CVT_J	       (20)	  /* blanking formula scale 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 */

/* Reduce blanking Version 2 */
#define CVT_RB_V2_H_BLANK     80       /* pixels */
#define CVT_RB_MIN_V_FPORCH    3       /* lines  */
#define CVT_RB_V2_MIN_V_FPORCH 1       /* lines  */
#define CVT_RB_V_BPORCH        6       /* lines  */

static int v_sync_from_aspect_ratio(int width, int height)
{
	if (((height * 4 / 3) / CVT_CELL_GRAN) * CVT_CELL_GRAN == width)
		return 4;

	if (((height * 16 / 9) / CVT_CELL_GRAN) * CVT_CELL_GRAN == width)
		return 5;

	if (((height * 16 / 10) / CVT_CELL_GRAN) * CVT_CELL_GRAN == width)
		return 6;

	if (((height * 5 / 4) / CVT_CELL_GRAN) * CVT_CELL_GRAN == width)
		return 7;

	if (((height * 15 / 9) / CVT_CELL_GRAN) * CVT_CELL_GRAN == width)
		return 7;

	/* custom aspect ratio */
	fprintf(stderr, "Warning!  Aspect ratio is not CVT Standard\n");
	return 10;
}

/**
 * calc_cvt_modeline - calculate modeline based on CVT algorithm
 *
 * This function is called to generate the timings according to CVT
 * algorithm. Timing calculation is based on VESA(TM) Coordinated
 * Video Timing Generator Rev 1.2 by  Graham Loveridge May 28, 2013
 * which can be downloaded from -
 * http://www.vesa.org/vesa-standards/free-standards/
 *
 * Input Parameters:
 * @image_width
 * @image_height
 * @refresh_rate
 * @reduced_blanking: This value, if greater than 0, indicates that
 * reduced blanking is to be used and value indicates the version.
 * @interlaced: whether to compute an interlaced mode
 * @reduced_fps: set the V4L2_DV_FL_REDUCED_FPS flag indicating that
 * the fps should be reduced by a factor of 1000 / 1001
 * @cvt: stores results of cvt timing calculation
 *
 * Returns:
 * true, if cvt timings are calculated and filled in cvt modeline.
 * false, for any error
 */

bool calc_cvt_modeline(int image_width, int image_height,
		       int refresh_rate, int reduced_blanking,
		       bool interlaced, bool reduced_fps,
		       struct v4l2_bt_timings *cvt)
{
	int h_sync;
	int v_sync;
	int h_fp;
	int h_bp;
	int v_fp;
	int v_bp;

	int h_pixel;
	int v_lines;
	int h_pixel_rnd;
	int v_lines_rnd;
	int active_h_pixel;
	int active_v_lines;
	int total_h_pixel;
	int total_v_lines;

	int h_blank;
	int v_blank;

	int h_period;

	int interlace;
	int v_refresh;
	int pixel_clock;
	int clk_gran;
	bool use_rb;
	bool rb_v2;

	if (!valid_params(image_width, image_height, refresh_rate))
		return false;

	use_rb = reduced_blanking > 0;
	rb_v2 = reduced_blanking == 2;

	clk_gran = rb_v2 ? CVT_PXL_CLK_GRAN_RB_V2 : CVT_PXL_CLK_GRAN;

	h_pixel = image_width;
	v_lines = image_height;

	if (!refresh_rate)
		v_refresh = 60;
	else
		v_refresh = refresh_rate;

	if (v_refresh != 50 && v_refresh != 60 &&
		v_refresh != 75 && v_refresh != 85)
		fprintf(stderr, "Warning!  Refresh rate is not CVT standard\n");

	if (interlaced) {
		interlace = 1;
		v_lines_rnd = v_lines / 2;
		v_refresh = v_refresh * 2;

		if ((v_lines_rnd * 2) != v_lines)
			fprintf(stderr,
			"Warning!  Vertical lines rounded to nearest integer\n");
	} else {
		interlace = 0;
		v_lines_rnd = v_lines;
	}

	h_pixel_rnd = h_pixel - (h_pixel % CVT_CELL_GRAN);

	if (h_pixel_rnd != h_pixel)
		fprintf(stderr,
		"Warning!  Horizontal pixels rounded to nearest character cell\n");

	active_h_pixel = h_pixel_rnd;
	active_v_lines = v_lines_rnd;

	v_sync = rb_v2 ? 8 : v_sync_from_aspect_ratio(h_pixel, v_lines);

	if (!use_rb) {
		int tmp1, tmp2;
		int ideal_blank_duty_cycle;
		int v_sync_bp;

		/* estimate the horizontal period */
		tmp1 = HV_FACTOR * 1000000  -
			   CVT_MIN_VSYNC_BP * HV_FACTOR * v_refresh;
		tmp2 = (active_v_lines + CVT_MIN_V_PORCH_RND) * 2 + interlace;

		h_period = tmp1 * 2 / (tmp2 * v_refresh);

		tmp1 = CVT_MIN_VSYNC_BP * HV_FACTOR / h_period + 1;

		if (tmp1 < (v_sync + CVT_MIN_V_PORCH_RND))
			v_sync_bp = v_sync + CVT_MIN_V_PORCH_RND;
		else
			v_sync_bp = tmp1;

		v_bp = v_sync_bp - v_sync;
		v_fp = CVT_MIN_V_PORCH_RND;

		ideal_blank_duty_cycle = (CVT_C_PRIME * HV_FACTOR) -
					  CVT_M_PRIME * h_period / 1000;

		if (ideal_blank_duty_cycle < 20 * HV_FACTOR)
			ideal_blank_duty_cycle = 20 * HV_FACTOR;

		h_blank = active_h_pixel * static_cast<long long>(ideal_blank_duty_cycle) /
			 (100 * HV_FACTOR - ideal_blank_duty_cycle);
		h_blank -= h_blank % (2 * CVT_CELL_GRAN);

		v_blank = v_sync_bp + CVT_MIN_V_PORCH_RND;

		total_h_pixel = active_h_pixel + h_blank;

		h_sync  = (total_h_pixel * CVT_HSYNC_PERCENT) / 100;
		h_sync -= h_sync % CVT_CELL_GRAN;

		h_bp = h_blank / 2;
		h_fp = h_blank - h_bp - h_sync;

		pixel_clock =  (static_cast<long long>(total_h_pixel) * HV_FACTOR * 1000000)
				/ h_period;
		pixel_clock -= pixel_clock  % clk_gran;
	} else {
		/* Reduced blanking */

		int vbi_lines;
		int tmp1, tmp2;
		int min_vbi_lines;

		/* estimate horizontal period. */
		tmp1 = HV_FACTOR * 1000000 -
			   CVT_RB_MIN_V_BLANK * HV_FACTOR * v_refresh;
		tmp2 = active_v_lines;

		h_period = tmp1 / (tmp2 * v_refresh);

		vbi_lines = CVT_RB_MIN_V_BLANK * HV_FACTOR / h_period + 1;

		if (rb_v2)
			min_vbi_lines = CVT_RB_V2_MIN_V_FPORCH + v_sync + CVT_RB_V_BPORCH;
		else
			min_vbi_lines = CVT_RB_V_FPORCH + v_sync + CVT_MIN_V_BPORCH;

		if (vbi_lines < min_vbi_lines)
			vbi_lines = min_vbi_lines;

		h_blank = rb_v2 ? CVT_RB_V2_H_BLANK : CVT_RB_H_BLANK;
		v_blank = vbi_lines;

		total_h_pixel = active_h_pixel + h_blank;
		total_v_lines = active_v_lines + v_blank;

		h_sync = CVT_RB_H_SYNC;

		h_bp = h_blank / 2;
		h_fp = h_blank - h_bp - h_sync;

		if (rb_v2) {
			v_bp = CVT_RB_V_BPORCH;
			v_fp = v_blank - v_bp - v_sync;
		} else {
			v_fp = CVT_RB_V_FPORCH;
			v_bp = v_blank - v_fp - v_sync;
		}

		pixel_clock = v_refresh * total_h_pixel *
			      (2 * total_v_lines + interlace) / 2;
		pixel_clock -= pixel_clock  % clk_gran;
	}

	cvt->standards 	 = V4L2_DV_BT_STD_CVT;

	cvt->width       = h_pixel;
	cvt->hfrontporch = h_fp;
	cvt->hsync       = h_sync;
	cvt->hbackporch  = h_bp;

	cvt->height      = v_lines;
	cvt->vfrontporch = v_fp;
	cvt->vsync       = v_sync;
	cvt->vbackporch  = v_bp;

	cvt->pixelclock = pixel_clock;
	cvt->interlaced = interlaced == 1 ?
			V4L2_DV_INTERLACED : V4L2_DV_PROGRESSIVE;

	if (cvt->interlaced == V4L2_DV_INTERLACED) {
		cvt->il_vfrontporch = v_fp;
		cvt->il_vsync = v_sync;
		cvt->il_vbackporch = v_bp;
		/* Add 1 to vbackporch of even field and set the half line
		 * flag (V4L2_DV_FL_HALF_LINE)
		 * For interlaced format, the half line flag indicates to the
		 * driver to add a half-line to the vfrontporch of the odd
		 * field and subtract a half-line from the vbackporch of the
		 * even field */
		cvt->flags |= V4L2_DV_FL_HALF_LINE;
		cvt->il_vbackporch += 1;
	}
	if (use_rb) {
		cvt->polarities = V4L2_DV_HSYNC_POS_POL;
		cvt->flags |= V4L2_DV_FL_REDUCED_BLANKING;
	} else {
		cvt->polarities = V4L2_DV_VSYNC_POS_POL;
	}
	if (rb_v2 && reduced_fps && v_refresh % 6 == 0)
		cvt->flags |= V4L2_DV_FL_REDUCED_FPS;

	return true;
}


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

#define GTF_MARGIN_PERCENT	  (18)
#define GTF_HSYNC_PERCENT	   (8)

#define GTF_PXL_CLK_GRAN (250000) /* pixel clock granularity */

#define GTF_V_SYNC_RQD	   (3) /* v sync required (lines) */
#define GTF_MIN_VSYNC_BP (550) /* min time vsync + back porch (us) */
#define GTF_MIN_PORCH	   (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)

/**
 * calc_gtf_modeline - calculate modeline based on GTF algorithm
 *
 * This function is called to generate the timings according to GTF
 * algorithm. Timing calculation is based on VESA(TM) Generalized
 * Timing Formula Standard Version 1.1 September 2, 1999
 * which can be downloaded from -
 * http://www.vesa.org/vesa-standards/free-standards/
 *
 * Input Parameters:
 * @image_width
 * @image_height
 * @refresh_rate
 * @reduced_blanking: This value, if greater than 0, indicates that
 * reduced blanking is to be used.
 * @interlaced: whether to compute an interlaced mode
 * @gtf: stores results of gtf timing calculation
 *
 * Returns:
 * true, if gtf timings are calculated and filled in gtf modeline.
 * false, for any error.
 */

bool calc_gtf_modeline(int image_width, int image_height,
		       int refresh_rate, bool reduced_blanking,
		       bool interlaced, struct v4l2_bt_timings *gtf)
{
	int h_sync;
	int v_sync;
	int h_fp;
	int h_bp;
	int v_fp;
	int v_bp;

	int h_pixel;
	int v_lines;
	int h_pixel_rnd;
	int v_lines_rnd;
	int active_h_pixel;
	int active_v_lines;
	int total_h_pixel;
	int total_v_lines;

	int h_blank;
	int v_blank;

	int h_period;
	int h_period_est;

	int interlace;
	int v_refresh;
	int v_refresh_est;
	int pixel_clock;

	int v_sync_bp;
	int tmp1, tmp2;
	int ideal_blank_duty_cycle;

	if (!gtf) {
		fprintf(stderr, "Null pointer to gtf modeline structure\n");
		return false;
	}

	if (!valid_params(image_width, image_height, refresh_rate))
		return false;

	h_pixel = image_width;
	v_lines = image_height;

	if (!refresh_rate)
		v_refresh = 60;
	else
		v_refresh = refresh_rate;

	if (interlaced) {
		interlace = 1;
		v_lines_rnd = (v_lines + 1) / 2;
		v_refresh = v_refresh * 2;
	} else {
		interlace = 0;
		v_lines_rnd = v_lines;
	}

	h_pixel_rnd = (h_pixel + GTF_CELL_GRAN / 2);
	h_pixel_rnd -= h_pixel_rnd % GTF_CELL_GRAN;

	active_h_pixel = h_pixel_rnd;
	active_v_lines = v_lines_rnd;

	/* estimate the horizontal period */
	tmp1 = HV_FACTOR * 1000000  -
		   GTF_MIN_VSYNC_BP * HV_FACTOR * v_refresh;
	tmp2 = 2 * (active_v_lines + GTF_MIN_PORCH) + interlace;

	h_period_est = 2 * tmp1 / (tmp2 * v_refresh);

	v_sync_bp = GTF_MIN_VSYNC_BP * HV_FACTOR * 100 / h_period_est;
	v_sync_bp = (v_sync_bp + 50) / 100;

	v_sync = GTF_V_SYNC_RQD;
	v_bp = v_sync_bp - v_sync;
	v_fp = GTF_MIN_PORCH;

	v_blank = v_sync + v_bp + v_fp;
	total_v_lines = active_v_lines + v_blank;

	v_refresh_est = (2 * HV_FACTOR * static_cast<long long>(1000000)) /
			(h_period_est * (2 * total_v_lines + interlace) / HV_FACTOR);

	h_period = (static_cast<long long>(h_period_est) * v_refresh_est) /
		   (v_refresh * HV_FACTOR);

	if (!reduced_blanking)
		ideal_blank_duty_cycle = (GTF_D_C_PRIME * HV_FACTOR) -
				      GTF_D_M_PRIME * h_period / 1000;
	else
		ideal_blank_duty_cycle = (GTF_S_C_PRIME * HV_FACTOR) -
				      GTF_S_M_PRIME * h_period / 1000;

	h_blank = active_h_pixel * static_cast<long long>(ideal_blank_duty_cycle) /
			 (100 * HV_FACTOR - ideal_blank_duty_cycle);
	h_blank = ((h_blank + GTF_CELL_GRAN) / (2 * GTF_CELL_GRAN))
			  * (2 * GTF_CELL_GRAN);
	total_h_pixel = active_h_pixel + h_blank;

	h_sync = (total_h_pixel * GTF_HSYNC_PERCENT) / 100;
	h_sync = ((h_sync + GTF_CELL_GRAN / 2) / GTF_CELL_GRAN) * GTF_CELL_GRAN;

	h_fp = h_blank / 2 - h_sync;
	h_bp = h_fp + h_sync;

	pixel_clock = (static_cast<long long>(total_h_pixel) * HV_FACTOR * 1000000)
					/ h_period;
	/* Not sure if clock value needs to be truncated to multiple
	 * of 25000. The formula given in standard does not indicate
	 * truncation
	 * */
	/*pixel_clock -= pixel_clock  % GTF_PXL_CLK_GRAN;*/
	gtf->standards 	 = V4L2_DV_BT_STD_GTF;

	gtf->width       = h_pixel;
	gtf->hfrontporch = h_fp;
	gtf->hsync       = h_sync;
	gtf->hbackporch  = h_bp;

	gtf->height      = v_lines;
	gtf->vfrontporch = v_fp;
	gtf->vsync       = v_sync;
	gtf->vbackporch  = v_bp;

	gtf->pixelclock = pixel_clock;
	gtf->interlaced = interlaced == 1 ?
			V4L2_DV_INTERLACED : V4L2_DV_PROGRESSIVE;

	if (gtf->interlaced == V4L2_DV_INTERLACED) {
		gtf->il_vfrontporch = v_fp;
		gtf->il_vsync = v_sync;
		gtf->il_vbackporch = v_bp;
		/* Add 1 to vbackporch of even field and set the half line
		 * flag (V4L2_DV_FL_HALF_LINE)
		 * For interlaced format, the half line flag indicates to the
		 * driver to add a half-line to the vfrontporch of the odd
		 * field and subtract a half-line from the vbackporch of the
		 * even field */
		gtf->flags |= V4L2_DV_FL_HALF_LINE;
		gtf->il_vbackporch += 1;
	}
	if (reduced_blanking) {
		gtf->polarities = V4L2_DV_HSYNC_POS_POL;
		gtf->flags |= V4L2_DV_FL_REDUCED_BLANKING;
	} else
		gtf->polarities = V4L2_DV_VSYNC_POS_POL;

	return true;
}