/* $NetBSD: vesagtf.c,v 1.3 2014/03/21 22:00:00 dholland Exp $ */
/*-
* Copyright (c) 2006 Itronix Inc.
* All rights reserved.
*
* Written by Garrett D'Amore for Itronix Inc.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of Itronix Inc. may not be used to endorse
* or promote products derived from this software without specific
* prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY ITRONIX INC. ``AS IS'' AND ANY EXPRESS
* OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL ITRONIX INC. BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
* GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*
* This was derived from a userland GTF program supplied by NVIDIA.
* NVIDIA's original boilerplate follows.
*
* Note that I have heavily modified the program for use in the EDID
* kernel code for NetBSD, including removing the use of floating
* point operations and making significant adjustments to minimize
* error propagation while operating with integer only math.
*
* This has required the use of 64-bit integers in a few places, but
* the upshot is that for a calculation of 1920x1200x85 (as an
* example), the error deviates by only ~.004% relative to the
* floating point version. This error is *well* within VESA
* tolerances.
*/
/*
* Copyright (c) 2001, Andy Ritger aritger@nvidia.com
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* o Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* o Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
* o Neither the name of NVIDIA nor the names of its contributors
* may be used to endorse or promote products derived from this
* software without specific prior written permission.
*
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT
* NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
* FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
* THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
*
*
* This program is based on the Generalized Timing Formula(GTF TM)
* Standard Version: 1.0, Revision: 1.0
*
* The GTF Document contains the following Copyright information:
*
* Copyright (c) 1994, 1995, 1996 - Video Electronics Standards
* Association. Duplication of this document within VESA member
* companies for review purposes is permitted. All other rights
* reserved.
*
* While every precaution has been taken in the preparation
* of this standard, the Video Electronics Standards Association and
* its contributors assume no responsibility for errors or omissions,
* and make no warranties, expressed or implied, of functionality
* of suitability for any purpose. The sample code contained within
* this standard may be used without restriction.
*
*
*
* The GTF EXCEL(TM) SPREADSHEET, a sample (and the definitive)
* implementation of the GTF Timing Standard, is available at:
*
* ftp://ftp.vesa.org/pub/GTF/GTF_V1R1.xls
*
*
*
* This program takes a desired resolution and vertical refresh rate,
* and computes mode timings according to the GTF Timing Standard.
* These mode timings can then be formatted as an XFree86 modeline
* or a mode description for use by fbset(8).
*
*
*
* NOTES:
*
* The GTF allows for computation of "margins" (the visible border
* surrounding the addressable video); on most non-overscan type
* systems, the margin period is zero. I've implemented the margin
* computations but not enabled it because 1) I don't really have
* any experience with this, and 2) neither XFree86 modelines nor
* fbset fb.modes provide an obvious way for margin timings to be
* included in their mode descriptions (needs more investigation).
*
* The GTF provides for computation of interlaced mode timings;
* I've implemented the computations but not enabled them, yet.
* I should probably enable and test this at some point.
*
*
*
* TODO:
*
* o Add support for interlaced modes.
*
* o Implement the other portions of the GTF: compute mode timings
* given either the desired pixel clock or the desired horizontal
* frequency.
*
* o It would be nice if this were more general purpose to do things
* outside the scope of the GTF: like generate double scan mode
* timings, for example.
*
* o Printing digits to the right of the decimal point when the
* digits are 0 annoys me.
*
* o Error checking.
*
*/
#ifdef _KERNEL
#include
__KERNEL_RCSID(0, "$NetBSD: vesagtf.c,v 1.3 2014/03/21 22:00:00 dholland Exp $");
#include
#include
#include
#include
#include
#else
#include
#include
#include
#include "videomode.h"
#include "vesagtf.h"
void print_xf86_mode(struct videomode *m);
#endif
#define CELL_GRAN 8 /* assumed character cell granularity */
/* C' and M' are part of the Blanking Duty Cycle computation */
/*
* #define C_PRIME (((C - J) * K/256.0) + J)
* #define M_PRIME (K/256.0 * M)
*/
/*
* C' and M' multiplied by 256 to give integer math. Make sure to
* scale results using these back down, appropriately.
*/
#define C_PRIME256(p) (((p->C - p->J) * p->K) + (p->J * 256))
#define M_PRIME256(p) (p->K * p->M)
#define DIVIDE(x,y) (((x) + ((y) / 2)) / (y))
/*
* print_value() - print the result of the named computation; this is
* useful when comparing against the GTF EXCEL spreadsheet.
*/
#ifdef GTFDEBUG
static void
print_value(int n, const char *name, unsigned val)
{
printf("%2d: %-27s: %u\n", n, name, val);
}
#else
#define print_value(n, name, val)
#endif
/*
* vert_refresh() - as defined by the GTF Timing Standard, compute the
* Stage 1 Parameters using the vertical refresh frequency. In other
* words: input a desired resolution and desired refresh rate, and
* output the GTF mode timings.
*
* XXX All the code is in place to compute interlaced modes, but I don't
* feel like testing it right now.
*
* XXX margin computations are implemented but not tested (nor used by
* XFree86 of fbset mode descriptions, from what I can tell).
*/
void
vesagtf_mode_params(unsigned h_pixels, unsigned v_lines, unsigned freq,
struct vesagtf_params *params, int flags, struct videomode *vmp)
{
unsigned v_field_rqd;
unsigned top_margin;
unsigned bottom_margin;
unsigned interlace;
uint64_t h_period_est;
unsigned vsync_plus_bp;
unsigned v_back_porch __unused;
unsigned total_v_lines;
uint64_t v_field_est;
uint64_t h_period;
unsigned v_field_rate;
unsigned v_frame_rate __unused;
unsigned left_margin;
unsigned right_margin;
unsigned total_active_pixels;
uint64_t ideal_duty_cycle;
unsigned h_blank;
unsigned total_pixels;
unsigned pixel_freq;
unsigned h_sync;
unsigned h_front_porch;
unsigned v_odd_front_porch_lines;
#ifdef GTFDEBUG
unsigned h_freq;
#endif
/* 1. In order to give correct results, the number of horizontal
* pixels requested is first processed to ensure that it is divisible
* by the character size, by rounding it to the nearest character
* cell boundary:
*
* [H PIXELS RND] = ((ROUND([H PIXELS]/[CELL GRAN RND],0))*[CELLGRAN RND])
*/
h_pixels = DIVIDE(h_pixels, CELL_GRAN) * CELL_GRAN;
print_value(1, "[H PIXELS RND]", h_pixels);
/* 2. If interlace is requested, the number of vertical lines assumed
* by the calculation must be halved, as the computation calculates
* the number of vertical lines per field. In either case, the
* number of lines is rounded to the nearest integer.
*
* [V LINES RND] = IF([INT RQD?]="y", ROUND([V LINES]/2,0),
* ROUND([V LINES],0))
*/
v_lines = (flags & VESAGTF_FLAG_ILACE) ? DIVIDE(v_lines, 2) : v_lines;
print_value(2, "[V LINES RND]", v_lines);
/* 3. Find the frame rate required:
*
* [V FIELD RATE RQD] = IF([INT RQD?]="y", [I/P FREQ RQD]*2,
* [I/P FREQ RQD])
*/
v_field_rqd = (flags & VESAGTF_FLAG_ILACE) ? (freq * 2) : (freq);
print_value(3, "[V FIELD RATE RQD]", v_field_rqd);
/* 4. Find number of lines in Top margin:
* 5. Find number of lines in Bottom margin:
*
* [TOP MARGIN (LINES)] = IF([MARGINS RQD?]="Y",
* ROUND(([MARGIN%]/100*[V LINES RND]),0),
* 0)
*
* Ditto for bottom margin. Note that instead of %, we use PPT, which
* is parts per thousand. This helps us with integer math.
*/
top_margin = bottom_margin = (flags & VESAGTF_FLAG_MARGINS) ?
DIVIDE(v_lines * params->margin_ppt, 1000) : 0;
print_value(4, "[TOP MARGIN (LINES)]", top_margin);
print_value(5, "[BOT MARGIN (LINES)]", bottom_margin);
/* 6. If interlace is required, then set variable [INTERLACE]=0.5:
*
* [INTERLACE]=(IF([INT RQD?]="y",0.5,0))
*
* To make this integer friendly, we use some special hacks in step
* 7 below. Please read those comments to understand why I am using
* a whole number of 1.0 instead of 0.5 here.
*/
interlace = (flags & VESAGTF_FLAG_ILACE) ? 1 : 0;
print_value(6, "[2*INTERLACE]", interlace);
/* 7. Estimate the Horizontal period
*
* [H PERIOD EST] = ((1/[V FIELD RATE RQD]) - [MIN VSYNC+BP]/1000000) /
* ([V LINES RND] + (2*[TOP MARGIN (LINES)]) +
* [MIN PORCH RND]+[INTERLACE]) * 1000000
*
* To make it integer friendly, we pre-multiply the 1000000 to get to
* usec. This gives us:
*
* [H PERIOD EST] = ((1000000/[V FIELD RATE RQD]) - [MIN VSYNC+BP]) /
* ([V LINES RND] + (2 * [TOP MARGIN (LINES)]) +
* [MIN PORCH RND]+[INTERLACE])
*
* The other problem is that the interlace value is wrong. To get
* the interlace to a whole number, we multiply both the numerator and
* divisor by 2, so we can use a value of either 1 or 0 for the interlace
* factor.
*
* This gives us:
*
* [H PERIOD EST] = ((2*((1000000/[V FIELD RATE RQD]) - [MIN VSYNC+BP])) /
* (2*([V LINES RND] + (2*[TOP MARGIN (LINES)]) +
* [MIN PORCH RND]) + [2*INTERLACE]))
*
* Finally we multiply by another 1000, to get value in picosec.
* Why picosec? To minimize rounding errors. Gotta love integer
* math and error propagation.
*/
h_period_est = DIVIDE(((DIVIDE(2000000000000ULL, v_field_rqd)) -
(2000000 * params->min_vsbp)),
((2 * (v_lines + (2 * top_margin) + params->min_porch)) + interlace));
print_value(7, "[H PERIOD EST (ps)]", h_period_est);
/* 8. Find the number of lines in V sync + back porch:
*
* [V SYNC+BP] = ROUND(([MIN VSYNC+BP]/[H PERIOD EST]),0)
*
* But recall that h_period_est is in psec. So multiply by 1000000.
*/
vsync_plus_bp = DIVIDE(params->min_vsbp * 1000000, h_period_est);
print_value(8, "[V SYNC+BP]", vsync_plus_bp);
/* 9. Find the number of lines in V back porch alone:
*
* [V BACK PORCH] = [V SYNC+BP] - [V SYNC RND]
*
* XXX is "[V SYNC RND]" a typo? should be [V SYNC RQD]?
*/
v_back_porch = vsync_plus_bp - params->vsync_rqd;
print_value(9, "[V BACK PORCH]", v_back_porch);
/* 10. Find the total number of lines in Vertical field period:
*
* [TOTAL V LINES] = [V LINES RND] + [TOP MARGIN (LINES)] +
* [BOT MARGIN (LINES)] + [V SYNC+BP] + [INTERLACE] +
* [MIN PORCH RND]
*/
total_v_lines = v_lines + top_margin + bottom_margin + vsync_plus_bp +
interlace + params->min_porch;
print_value(10, "[TOTAL V LINES]", total_v_lines);
/* 11. Estimate the Vertical field frequency:
*
* [V FIELD RATE EST] = 1 / [H PERIOD EST] / [TOTAL V LINES] * 1000000
*
* Again, we want to pre multiply by 10^9 to convert for nsec, thereby
* making it usable in integer math.
*
* So we get:
*
* [V FIELD RATE EST] = 1000000000 / [H PERIOD EST] / [TOTAL V LINES]
*
* This is all scaled to get the result in uHz. Again, we're trying to
* minimize error propagation.
*/
v_field_est = DIVIDE(DIVIDE(1000000000000000ULL, h_period_est),
total_v_lines);
print_value(11, "[V FIELD RATE EST(uHz)]", v_field_est);
/* 12. Find the actual horizontal period:
*
* [H PERIOD] = [H PERIOD EST] / ([V FIELD RATE RQD] / [V FIELD RATE EST])
*/
h_period = DIVIDE(h_period_est * v_field_est, v_field_rqd * 1000);
print_value(12, "[H PERIOD(ps)]", h_period);
/* 13. Find the actual Vertical field frequency:
*
* [V FIELD RATE] = 1 / [H PERIOD] / [TOTAL V LINES] * 1000000
*
* And again, we convert to nsec ahead of time, giving us:
*
* [V FIELD RATE] = 1000000 / [H PERIOD] / [TOTAL V LINES]
*
* And another rescaling back to mHz. Gotta love it.
*/
v_field_rate = DIVIDE(1000000000000ULL, h_period * total_v_lines);
print_value(13, "[V FIELD RATE]", v_field_rate);
/* 14. Find the Vertical frame frequency:
*
* [V FRAME RATE] = (IF([INT RQD?]="y", [V FIELD RATE]/2, [V FIELD RATE]))
*
* N.B. that the result here is in mHz.
*/
v_frame_rate = (flags & VESAGTF_FLAG_ILACE) ?
v_field_rate / 2 : v_field_rate;
print_value(14, "[V FRAME RATE]", v_frame_rate);
/* 15. Find number of pixels in left margin:
* 16. Find number of pixels in right margin:
*
* [LEFT MARGIN (PIXELS)] = (IF( [MARGINS RQD?]="Y",
* (ROUND( ([H PIXELS RND] * [MARGIN%] / 100 /
* [CELL GRAN RND]),0)) * [CELL GRAN RND],
* 0))
*
* Again, we deal with margin percentages as PPT (parts per thousand).
* And the calculations for left and right are the same.
*/
left_margin = right_margin = (flags & VESAGTF_FLAG_MARGINS) ?
DIVIDE(DIVIDE(h_pixels * params->margin_ppt, 1000),
CELL_GRAN) * CELL_GRAN : 0;
print_value(15, "[LEFT MARGIN (PIXELS)]", left_margin);
print_value(16, "[RIGHT MARGIN (PIXELS)]", right_margin);
/* 17. Find total number of active pixels in image and left and right
* margins:
*
* [TOTAL ACTIVE PIXELS] = [H PIXELS RND] + [LEFT MARGIN (PIXELS)] +
* [RIGHT MARGIN (PIXELS)]
*/
total_active_pixels = h_pixels + left_margin + right_margin;
print_value(17, "[TOTAL ACTIVE PIXELS]", total_active_pixels);
/* 18. Find the ideal blanking duty cycle from the blanking duty cycle
* equation:
*
* [IDEAL DUTY CYCLE] = [C'] - ([M']*[H PERIOD]/1000)
*
* However, we have modified values for [C'] as [256*C'] and
* [M'] as [256*M']. Again the idea here is to get good scaling.
* We use 256 as the factor to make the math fast.
*
* Note that this means that we have to scale it appropriately in
* later calculations.
*
* The ending result is that our ideal_duty_cycle is 256000x larger
* than the duty cycle used by VESA. But again, this reduces error
* propagation.
*/
ideal_duty_cycle =
((C_PRIME256(params) * 1000) -
(M_PRIME256(params) * h_period / 1000000));
print_value(18, "[IDEAL DUTY CYCLE]", ideal_duty_cycle);
/* 19. Find the number of pixels in the blanking time to the nearest
* double character cell:
*
* [H BLANK (PIXELS)] = (ROUND(([TOTAL ACTIVE PIXELS] *
* [IDEAL DUTY CYCLE] /
* (100-[IDEAL DUTY CYCLE]) /
* (2*[CELL GRAN RND])), 0))
* * (2*[CELL GRAN RND])
*
* Of course, we adjust to make this rounding work in integer math.
*/
h_blank = DIVIDE(DIVIDE(total_active_pixels * ideal_duty_cycle,
(256000 * 100ULL) - ideal_duty_cycle),
2 * CELL_GRAN) * (2 * CELL_GRAN);
print_value(19, "[H BLANK (PIXELS)]", h_blank);
/* 20. Find total number of pixels:
*
* [TOTAL PIXELS] = [TOTAL ACTIVE PIXELS] + [H BLANK (PIXELS)]
*/
total_pixels = total_active_pixels + h_blank;
print_value(20, "[TOTAL PIXELS]", total_pixels);
/* 21. Find pixel clock frequency:
*
* [PIXEL FREQ] = [TOTAL PIXELS] / [H PERIOD]
*
* We calculate this in Hz rather than MHz, to get a value that
* is usable with integer math. Recall that the [H PERIOD] is in
* nsec.
*/
pixel_freq = DIVIDE(total_pixels * 1000000, DIVIDE(h_period, 1000));
print_value(21, "[PIXEL FREQ]", pixel_freq);
/* 22. Find horizontal frequency:
*
* [H FREQ] = 1000 / [H PERIOD]
*
* I've ifdef'd this out, because we don't need it for any of
* our calculations.
* We calculate this in Hz rather than kHz, to avoid rounding
* errors. Recall that the [H PERIOD] is in usec.
*/
#ifdef GTFDEBUG
h_freq = 1000000000 / h_period;
print_value(22, "[H FREQ]", h_freq);
#endif
/* Stage 1 computations are now complete; I should really pass
the results to another function and do the Stage 2
computations, but I only need a few more values so I'll just
append the computations here for now */
/* 17. Find the number of pixels in the horizontal sync period:
*
* [H SYNC (PIXELS)] =(ROUND(([H SYNC%] / 100 * [TOTAL PIXELS] /
* [CELL GRAN RND]),0))*[CELL GRAN RND]
*
* Rewriting for integer math:
*
* [H SYNC (PIXELS)]=(ROUND((H SYNC%] * [TOTAL PIXELS] / 100 /
* [CELL GRAN RND),0))*[CELL GRAN RND]
*/
h_sync = DIVIDE(((params->hsync_pct * total_pixels) / 100), CELL_GRAN) *
CELL_GRAN;
print_value(17, "[H SYNC (PIXELS)]", h_sync);
/* 18. Find the number of pixels in the horizontal front porch period:
*
* [H FRONT PORCH (PIXELS)] = ([H BLANK (PIXELS)]/2)-[H SYNC (PIXELS)]
*
* Note that h_blank is always an even number of characters (i.e.
* h_blank % (CELL_GRAN * 2) == 0)
*/
h_front_porch = (h_blank / 2) - h_sync;
print_value(18, "[H FRONT PORCH (PIXELS)]", h_front_porch);
/* 36. Find the number of lines in the odd front porch period:
*
* [V ODD FRONT PORCH(LINES)]=([MIN PORCH RND]+[INTERLACE])
*
* Adjusting for the fact that the interlace is scaled:
*
* [V ODD FRONT PORCH(LINES)]=(([MIN PORCH RND] * 2) + [2*INTERLACE]) / 2
*/
v_odd_front_porch_lines = ((2 * params->min_porch) + interlace) / 2;
print_value(36, "[V ODD FRONT PORCH(LINES)]", v_odd_front_porch_lines);
/* finally, pack the results in the mode struct */
vmp->hsync_start = h_pixels + h_front_porch;
vmp->hsync_end = vmp->hsync_start + h_sync;
vmp->htotal = total_pixels;
vmp->hdisplay = h_pixels;
vmp->vsync_start = v_lines + v_odd_front_porch_lines;
vmp->vsync_end = vmp->vsync_start + params->vsync_rqd;
vmp->vtotal = total_v_lines;
vmp->vdisplay = v_lines;
vmp->dot_clock = pixel_freq;
}
void
vesagtf_mode(unsigned x, unsigned y, unsigned refresh, struct videomode *vmp)
{
struct vesagtf_params params;
params.margin_ppt = VESAGTF_MARGIN_PPT;
params.min_porch = VESAGTF_MIN_PORCH;
params.vsync_rqd = VESAGTF_VSYNC_RQD;
params.hsync_pct = VESAGTF_HSYNC_PCT;
params.min_vsbp = VESAGTF_MIN_VSBP;
params.M = VESAGTF_M;
params.C = VESAGTF_C;
params.K = VESAGTF_K;
params.J = VESAGTF_J;
vesagtf_mode_params(x, y, refresh, ¶ms, 0, vmp);
}
/*
* The tidbit here is so that you can compile this file as a
* standalone user program to generate X11 modelines using VESA GTF.
* This also allows for testing of the code itself, without
* necessitating a full kernel recompile.
*/
/* print_xf86_mode() - print the XFree86 modeline, given mode timings. */
#ifndef _KERNEL
void
print_xf86_mode (struct videomode *vmp)
{
float vf, hf;
hf = 1000.0 * vmp->dot_clock / vmp->htotal;
vf = 1.0 * hf / vmp->vtotal;
printf("\n");
printf(" # %dx%d @ %.2f Hz (GTF) hsync: %.2f kHz; pclk: %.2f MHz\n",
vmp->hdisplay, vmp->vdisplay, vf, hf, vmp->dot_clock / 1000.0);
printf(" Modeline \"%dx%d_%.2f\" %.2f"
" %d %d %d %d"
" %d %d %d %d"
" -HSync +Vsync\n\n",
vmp->hdisplay, vmp->vdisplay, vf, (vmp->dot_clock / 1000.0),
vmp->hdisplay, vmp->hsync_start, vmp->hsync_end, vmp->htotal,
vmp->vdisplay, vmp->vsync_start, vmp->vsync_end, vmp->vtotal);
}
int
main (int argc, char *argv[])
{
struct videomode m;
if (argc != 4) {
printf("usage: %s x y refresh\n", argv[0]);
exit(1);
}
vesagtf_mode(atoi(argv[1]), atoi(argv[2]), atoi(argv[3]), &m);
print_xf86_mode(&m);
return 0;
}
#endif