/* $NetBSD: vesagtf.c,v 1.1 2006/05/11 01:49:53 gdamore 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 propogation 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 1.1 2006/05/11 01:49:53 gdamore 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; unsigned total_v_lines; uint64_t v_field_est; uint64_t h_period; unsigned v_field_rate; unsigned v_frame_rate; 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 propogation. */ 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 propogation. */ 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 * propogation. */ 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