Bug Summary

File:dev/videomode/vesagtf.c
Warning:line 370, column 5
Value stored to 'v_back_porch' is never read

Annotated Source Code

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clang -cc1 -cc1 -triple amd64-unknown-openbsd7.0 -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name vesagtf.c -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -mrelocation-model static -mframe-pointer=all -relaxed-aliasing -fno-rounding-math -mconstructor-aliases -ffreestanding -mcmodel=kernel -target-cpu x86-64 -target-feature +retpoline-indirect-calls -target-feature +retpoline-indirect-branches -target-feature -sse2 -target-feature -sse -target-feature -3dnow -target-feature -mmx -target-feature +save-args -disable-red-zone -no-implicit-float -tune-cpu generic -debugger-tuning=gdb -fcoverage-compilation-dir=/usr/src/sys/arch/amd64/compile/GENERIC.MP/obj -nostdsysteminc -nobuiltininc -resource-dir /usr/local/lib/clang/13.0.0 -I /usr/src/sys -I /usr/src/sys/arch/amd64/compile/GENERIC.MP/obj -I /usr/src/sys/arch -I /usr/src/sys/dev/pci/drm/include -I /usr/src/sys/dev/pci/drm/include/uapi -I /usr/src/sys/dev/pci/drm/amd/include/asic_reg -I /usr/src/sys/dev/pci/drm/amd/include -I /usr/src/sys/dev/pci/drm/amd/amdgpu -I /usr/src/sys/dev/pci/drm/amd/display -I /usr/src/sys/dev/pci/drm/amd/display/include -I /usr/src/sys/dev/pci/drm/amd/display/dc -I /usr/src/sys/dev/pci/drm/amd/display/amdgpu_dm -I /usr/src/sys/dev/pci/drm/amd/pm/inc -I /usr/src/sys/dev/pci/drm/amd/pm/swsmu -I /usr/src/sys/dev/pci/drm/amd/pm/swsmu/smu11 -I /usr/src/sys/dev/pci/drm/amd/pm/swsmu/smu12 -I /usr/src/sys/dev/pci/drm/amd/pm/powerplay -I /usr/src/sys/dev/pci/drm/amd/pm/powerplay/hwmgr -I /usr/src/sys/dev/pci/drm/amd/pm/powerplay/smumgr -I /usr/src/sys/dev/pci/drm/amd/display/dc/inc -I /usr/src/sys/dev/pci/drm/amd/display/dc/inc/hw -I /usr/src/sys/dev/pci/drm/amd/display/dc/clk_mgr -I /usr/src/sys/dev/pci/drm/amd/display/modules/inc -I /usr/src/sys/dev/pci/drm/amd/display/modules/hdcp -I /usr/src/sys/dev/pci/drm/amd/display/dmub/inc -I /usr/src/sys/dev/pci/drm/i915 -D DDB -D DIAGNOSTIC -D KTRACE -D ACCOUNTING -D KMEMSTATS -D PTRACE -D POOL_DEBUG -D CRYPTO -D SYSVMSG -D SYSVSEM -D SYSVSHM -D UVM_SWAP_ENCRYPT -D FFS -D FFS2 -D FFS_SOFTUPDATES -D UFS_DIRHASH -D QUOTA -D EXT2FS -D MFS -D NFSCLIENT -D NFSSERVER -D CD9660 -D UDF -D MSDOSFS -D FIFO -D FUSE -D SOCKET_SPLICE -D TCP_ECN -D TCP_SIGNATURE -D INET6 -D IPSEC -D PPP_BSDCOMP -D PPP_DEFLATE -D PIPEX -D MROUTING -D MPLS -D BOOT_CONFIG -D USER_PCICONF -D APERTURE -D MTRR -D NTFS -D HIBERNATE -D PCIVERBOSE -D USBVERBOSE -D WSDISPLAY_COMPAT_USL -D WSDISPLAY_COMPAT_RAWKBD -D WSDISPLAY_DEFAULTSCREENS=6 -D X86EMU -D ONEWIREVERBOSE -D MULTIPROCESSOR -D MAXUSERS=80 -D _KERNEL -D CONFIG_DRM_AMD_DC_DCN3_0 -O2 -Wno-pointer-sign -Wno-address-of-packed-member -Wno-constant-conversion -Wno-unused-but-set-variable -Wno-gnu-folding-constant -fdebug-compilation-dir=/usr/src/sys/arch/amd64/compile/GENERIC.MP/obj -ferror-limit 19 -fwrapv -D_RET_PROTECTOR -ret-protector -fgnuc-version=4.2.1 -vectorize-loops -vectorize-slp -fno-builtin-malloc -fno-builtin-calloc -fno-builtin-realloc -fno-builtin-valloc -fno-builtin-free -fno-builtin-strdup -fno-builtin-strndup -analyzer-output=html -faddrsig -o /usr/obj/sys/arch/amd64/compile/GENERIC.MP/scan-build/2022-01-12-131800-47421-1 -x c /usr/src/sys/dev/videomode/vesagtf.c
1/* $NetBSD: vesagtf.c,v 1.1 2006/05/11 01:49:53 gdamore Exp $ */
2
3/*-
4 * Copyright (c) 2006 Itronix Inc.
5 * All rights reserved.
6 *
7 * Written by Garrett D'Amore for Itronix Inc.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 * 3. The name of Itronix Inc. may not be used to endorse
18 * or promote products derived from this software without specific
19 * prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY ITRONIX INC. ``AS IS'' AND ANY EXPRESS
22 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
23 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL ITRONIX INC. BE LIABLE FOR ANY
25 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
27 * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
28 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
29 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
30 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
31 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32 */
33
34/*
35 * This was derived from a userland GTF program supplied by NVIDIA.
36 * NVIDIA's original boilerplate follows.
37 *
38 * Note that I have heavily modified the program for use in the EDID
39 * kernel code for NetBSD, including removing the use of floating
40 * point operations and making significant adjustments to minimize
41 * error propagation while operating with integer only math.
42 *
43 * This has required the use of 64-bit integers in a few places, but
44 * the upshot is that for a calculation of 1920x1200x85 (as an
45 * example), the error deviates by only ~.004% relative to the
46 * floating point version. This error is *well* within VESA
47 * tolerances.
48 */
49
50/*
51 * Copyright (c) 2001, Andy Ritger aritger@nvidia.com
52 * All rights reserved.
53 *
54 * Redistribution and use in source and binary forms, with or without
55 * modification, are permitted provided that the following conditions
56 * are met:
57 *
58 * o Redistributions of source code must retain the above copyright
59 * notice, this list of conditions and the following disclaimer.
60 * o Redistributions in binary form must reproduce the above copyright
61 * notice, this list of conditions and the following disclaimer
62 * in the documentation and/or other materials provided with the
63 * distribution.
64 * o Neither the name of NVIDIA nor the names of its contributors
65 * may be used to endorse or promote products derived from this
66 * software without specific prior written permission.
67 *
68 *
69 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
70 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT
71 * NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
72 * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
73 * THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
74 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
75 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
76 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
77 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
78 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
79 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
80 * POSSIBILITY OF SUCH DAMAGE.
81 *
82 *
83 *
84 * This program is based on the Generalized Timing Formula(GTF TM)
85 * Standard Version: 1.0, Revision: 1.0
86 *
87 * The GTF Document contains the following Copyright information:
88 *
89 * Copyright (c) 1994, 1995, 1996 - Video Electronics Standards
90 * Association. Duplication of this document within VESA member
91 * companies for review purposes is permitted. All other rights
92 * reserved.
93 *
94 * While every precaution has been taken in the preparation
95 * of this standard, the Video Electronics Standards Association and
96 * its contributors assume no responsibility for errors or omissions,
97 * and make no warranties, expressed or implied, of functionality
98 * of suitability for any purpose. The sample code contained within
99 * this standard may be used without restriction.
100 *
101 *
102 *
103 * The GTF EXCEL(TM) SPREADSHEET, a sample (and the definitive)
104 * implementation of the GTF Timing Standard, is available at:
105 *
106 * ftp://ftp.vesa.org/pub/GTF/GTF_V1R1.xls
107 *
108 *
109 *
110 * This program takes a desired resolution and vertical refresh rate,
111 * and computes mode timings according to the GTF Timing Standard.
112 * These mode timings can then be formatted as an XFree86 modeline
113 * or a mode description for use by fbset(8).
114 *
115 *
116 *
117 * NOTES:
118 *
119 * The GTF allows for computation of "margins" (the visible border
120 * surrounding the addressable video); on most non-overscan type
121 * systems, the margin period is zero. I've implemented the margin
122 * computations but not enabled it because 1) I don't really have
123 * any experience with this, and 2) neither XFree86 modelines nor
124 * fbset fb.modes provide an obvious way for margin timings to be
125 * included in their mode descriptions (needs more investigation).
126 *
127 * The GTF provides for computation of interlaced mode timings;
128 * I've implemented the computations but not enabled them, yet.
129 * I should probably enable and test this at some point.
130 *
131 *
132 *
133 * TODO:
134 *
135 * o Add support for interlaced modes.
136 *
137 * o Implement the other portions of the GTF: compute mode timings
138 * given either the desired pixel clock or the desired horizontal
139 * frequency.
140 *
141 * o It would be nice if this were more general purpose to do things
142 * outside the scope of the GTF: like generate double scan mode
143 * timings, for example.
144 *
145 * o Printing digits to the right of the decimal point when the
146 * digits are 0 annoys me.
147 *
148 * o Error checking.
149 *
150 */
151
152
153#ifdef _KERNEL1
154#include <sys/param.h>
155#include <sys/systm.h>
156#include <dev/videomode/videomode.h>
157#include <dev/videomode/vesagtf.h>
158#else
159#include <sys/types.h>
160#include "videomode.h"
161#include "vesagtf.h"
162#include <stdio.h>
163#include <stdlib.h>
164void print_xf86_mode(struct videomode *m);
165#endif
166
167#define CELL_GRAN8 8 /* assumed character cell granularity */
168
169/* C' and M' are part of the Blanking Duty Cycle computation */
170/*
171 * #define C_PRIME (((C - J) * K/256.0) + J)
172 * #define M_PRIME (K/256.0 * M)
173 */
174
175/*
176 * C' and M' multiplied by 256 to give integer math. Make sure to
177 * scale results using these back down, appropriately.
178 */
179#define C_PRIME256(p)(((p->C - p->J) * p->K) + (p->J * 256)) (((p->C - p->J) * p->K) + (p->J * 256))
180#define M_PRIME256(p)(p->K * p->M) (p->K * p->M)
181
182#define DIVIDE(x,y)(((x) + ((y) / 2)) / (y)) (((x) + ((y) / 2)) / (y))
183
184/*
185 * print_value() - print the result of the named computation; this is
186 * useful when comparing against the GTF EXCEL spreadsheet.
187 */
188
189#ifdef GTFDEBUG
190
191void
192print_value(int n, const char *name, unsigned val)
193{
194 printf("%2d: %-27s: %u\n", n, name, val);
195}
196#else
197#define print_value(n, name, val)
198#endif
199
200
201/*
202 * vert_refresh() - as defined by the GTF Timing Standard, compute the
203 * Stage 1 Parameters using the vertical refresh frequency. In other
204 * words: input a desired resolution and desired refresh rate, and
205 * output the GTF mode timings.
206 *
207 * XXX All the code is in place to compute interlaced modes, but I don't
208 * feel like testing it right now.
209 *
210 * XXX margin computations are implemented but not tested (nor used by
211 * XFree86 of fbset mode descriptions, from what I can tell).
212 */
213
214void
215vesagtf_mode_params(unsigned h_pixels, unsigned v_lines, unsigned freq,
216 struct vesagtf_params *params, int flags, struct videomode *vmp)
217{
218 unsigned v_field_rqd;
219 unsigned top_margin;
220 unsigned bottom_margin;
221 unsigned interlace;
222 uint64_t h_period_est;
223 unsigned vsync_plus_bp;
224 unsigned v_back_porch;
225 unsigned total_v_lines;
226 uint64_t v_field_est;
227 uint64_t h_period;
228 unsigned v_field_rate;
229 unsigned v_frame_rate;
230 unsigned left_margin;
231 unsigned right_margin;
232 unsigned total_active_pixels;
233 uint64_t ideal_duty_cycle;
234 unsigned h_blank;
235 unsigned total_pixels;
236 unsigned pixel_freq;
237
238 unsigned h_sync;
239 unsigned h_front_porch;
240 unsigned v_odd_front_porch_lines;
241
242#ifdef GTFDEBUG
243 unsigned h_freq;
244#endif
245
246 /* 1. In order to give correct results, the number of horizontal
247 * pixels requested is first processed to ensure that it is divisible
248 * by the character size, by rounding it to the nearest character
249 * cell boundary:
250 *
251 * [H PIXELS RND] = ((ROUND([H PIXELS]/[CELL GRAN RND],0))*[CELLGRAN RND])
252 */
253
254 h_pixels = DIVIDE(h_pixels, CELL_GRAN)(((h_pixels) + ((8) / 2)) / (8)) * CELL_GRAN8;
255
256 print_value(1, "[H PIXELS RND]", h_pixels);
257
258
259 /* 2. If interlace is requested, the number of vertical lines assumed
260 * by the calculation must be halved, as the computation calculates
261 * the number of vertical lines per field. In either case, the
262 * number of lines is rounded to the nearest integer.
263 *
264 * [V LINES RND] = IF([INT RQD?]="y", ROUND([V LINES]/2,0),
265 * ROUND([V LINES],0))
266 */
267
268 v_lines = (flags & VESAGTF_FLAG_ILACE0x0001) ? DIVIDE(v_lines, 2)(((v_lines) + ((2) / 2)) / (2)) : v_lines;
269
270 print_value(2, "[V LINES RND]", v_lines);
271
272
273 /* 3. Find the frame rate required:
274 *
275 * [V FIELD RATE RQD] = IF([INT RQD?]="y", [I/P FREQ RQD]*2,
276 * [I/P FREQ RQD])
277 */
278
279 v_field_rqd = (flags & VESAGTF_FLAG_ILACE0x0001) ? (freq * 2) : (freq);
280
281 print_value(3, "[V FIELD RATE RQD]", v_field_rqd);
282
283
284 /* 4. Find number of lines in Top margin:
285 * 5. Find number of lines in Bottom margin:
286 *
287 * [TOP MARGIN (LINES)] = IF([MARGINS RQD?]="Y",
288 * ROUND(([MARGIN%]/100*[V LINES RND]),0),
289 * 0)
290 *
291 * Ditto for bottom margin. Note that instead of %, we use PPT, which
292 * is parts per thousand. This helps us with integer math.
293 */
294
295 top_margin = bottom_margin = (flags & VESAGTF_FLAG_MARGINS0x0002) ?
296 DIVIDE(v_lines * params->margin_ppt, 1000)(((v_lines * params->margin_ppt) + ((1000) / 2)) / (1000)) : 0;
297
298 print_value(4, "[TOP MARGIN (LINES)]", top_margin);
299 print_value(5, "[BOT MARGIN (LINES)]", bottom_margin);
300
301
302 /* 6. If interlace is required, then set variable [INTERLACE]=0.5:
303 *
304 * [INTERLACE]=(IF([INT RQD?]="y",0.5,0))
305 *
306 * To make this integer friendly, we use some special hacks in step
307 * 7 below. Please read those comments to understand why I am using
308 * a whole number of 1.0 instead of 0.5 here.
309 */
310 interlace = (flags & VESAGTF_FLAG_ILACE0x0001) ? 1 : 0;
311
312 print_value(6, "[2*INTERLACE]", interlace);
313
314
315 /* 7. Estimate the Horizontal period
316 *
317 * [H PERIOD EST] = ((1/[V FIELD RATE RQD]) - [MIN VSYNC+BP]/1000000) /
318 * ([V LINES RND] + (2*[TOP MARGIN (LINES)]) +
319 * [MIN PORCH RND]+[INTERLACE]) * 1000000
320 *
321 * To make it integer friendly, we pre-multiply the 1000000 to get to
322 * usec. This gives us:
323 *
324 * [H PERIOD EST] = ((1000000/[V FIELD RATE RQD]) - [MIN VSYNC+BP]) /
325 * ([V LINES RND] + (2 * [TOP MARGIN (LINES)]) +
326 * [MIN PORCH RND]+[INTERLACE])
327 *
328 * The other problem is that the interlace value is wrong. To get
329 * the interlace to a whole number, we multiply both the numerator and
330 * divisor by 2, so we can use a value of either 1 or 0 for the interlace
331 * factor.
332 *
333 * This gives us:
334 *
335 * [H PERIOD EST] = ((2*((1000000/[V FIELD RATE RQD]) - [MIN VSYNC+BP])) /
336 * (2*([V LINES RND] + (2*[TOP MARGIN (LINES)]) +
337 * [MIN PORCH RND]) + [2*INTERLACE]))
338 *
339 * Finally we multiply by another 1000, to get value in picosec.
340 * Why picosec? To minimize rounding errors. Gotta love integer
341 * math and error propagation.
342 */
343
344 h_period_est = DIVIDE(((DIVIDE(2000000000000ULL, v_field_rqd)) -((((((((2000000000000ULL) + ((v_field_rqd) / 2)) / (v_field_rqd
))) - (2000000 * params->min_vsbp))) + ((((2 * (v_lines + (
2 * top_margin) + params->min_porch)) + interlace)) / 2)) /
(((2 * (v_lines + (2 * top_margin) + params->min_porch)) +
interlace)))
345 (2000000 * params->min_vsbp)),((((((((2000000000000ULL) + ((v_field_rqd) / 2)) / (v_field_rqd
))) - (2000000 * params->min_vsbp))) + ((((2 * (v_lines + (
2 * top_margin) + params->min_porch)) + interlace)) / 2)) /
(((2 * (v_lines + (2 * top_margin) + params->min_porch)) +
interlace)))
346 ((2 * (v_lines + (2 * top_margin) + params->min_porch)) + interlace))((((((((2000000000000ULL) + ((v_field_rqd) / 2)) / (v_field_rqd
))) - (2000000 * params->min_vsbp))) + ((((2 * (v_lines + (
2 * top_margin) + params->min_porch)) + interlace)) / 2)) /
(((2 * (v_lines + (2 * top_margin) + params->min_porch)) +
interlace)));
347
348 print_value(7, "[H PERIOD EST (ps)]", h_period_est);
349
350
351 /* 8. Find the number of lines in V sync + back porch:
352 *
353 * [V SYNC+BP] = ROUND(([MIN VSYNC+BP]/[H PERIOD EST]),0)
354 *
355 * But recall that h_period_est is in psec. So multiply by 1000000.
356 */
357
358 vsync_plus_bp = DIVIDE(params->min_vsbp * 1000000, h_period_est)(((params->min_vsbp * 1000000) + ((h_period_est) / 2)) / (
h_period_est));
359
360 print_value(8, "[V SYNC+BP]", vsync_plus_bp);
361
362
363 /* 9. Find the number of lines in V back porch alone:
364 *
365 * [V BACK PORCH] = [V SYNC+BP] - [V SYNC RND]
366 *
367 * XXX is "[V SYNC RND]" a typo? should be [V SYNC RQD]?
368 */
369
370 v_back_porch = vsync_plus_bp - params->vsync_rqd;
Value stored to 'v_back_porch' is never read
371
372 print_value(9, "[V BACK PORCH]", v_back_porch);
373
374
375 /* 10. Find the total number of lines in Vertical field period:
376 *
377 * [TOTAL V LINES] = [V LINES RND] + [TOP MARGIN (LINES)] +
378 * [BOT MARGIN (LINES)] + [V SYNC+BP] + [INTERLACE] +
379 * [MIN PORCH RND]
380 */
381
382 total_v_lines = v_lines + top_margin + bottom_margin + vsync_plus_bp +
383 interlace + params->min_porch;
384
385 print_value(10, "[TOTAL V LINES]", total_v_lines);
386
387
388 /* 11. Estimate the Vertical field frequency:
389 *
390 * [V FIELD RATE EST] = 1 / [H PERIOD EST] / [TOTAL V LINES] * 1000000
391 *
392 * Again, we want to pre multiply by 10^9 to convert for nsec, thereby
393 * making it usable in integer math.
394 *
395 * So we get:
396 *
397 * [V FIELD RATE EST] = 1000000000 / [H PERIOD EST] / [TOTAL V LINES]
398 *
399 * This is all scaled to get the result in uHz. Again, we're trying to
400 * minimize error propagation.
401 */
402 v_field_est = DIVIDE(DIVIDE(1000000000000000ULL, h_period_est),((((((1000000000000000ULL) + ((h_period_est) / 2)) / (h_period_est
))) + ((total_v_lines) / 2)) / (total_v_lines))
403 total_v_lines)((((((1000000000000000ULL) + ((h_period_est) / 2)) / (h_period_est
))) + ((total_v_lines) / 2)) / (total_v_lines));
404
405 print_value(11, "[V FIELD RATE EST(uHz)]", v_field_est);
406
407
408 /* 12. Find the actual horizontal period:
409 *
410 * [H PERIOD] = [H PERIOD EST] / ([V FIELD RATE RQD] / [V FIELD RATE EST])
411 */
412
413 h_period = DIVIDE(h_period_est * v_field_est, v_field_rqd * 1000)(((h_period_est * v_field_est) + ((v_field_rqd * 1000) / 2)) /
(v_field_rqd * 1000));
414
415 print_value(12, "[H PERIOD(ps)]", h_period);
416
417
418 /* 13. Find the actual Vertical field frequency:
419 *
420 * [V FIELD RATE] = 1 / [H PERIOD] / [TOTAL V LINES] * 1000000
421 *
422 * And again, we convert to nsec ahead of time, giving us:
423 *
424 * [V FIELD RATE] = 1000000 / [H PERIOD] / [TOTAL V LINES]
425 *
426 * And another rescaling back to mHz. Gotta love it.
427 */
428
429 v_field_rate = DIVIDE(1000000000000ULL, h_period * total_v_lines)(((1000000000000ULL) + ((h_period * total_v_lines) / 2)) / (h_period
* total_v_lines));
430
431 print_value(13, "[V FIELD RATE]", v_field_rate);
432
433
434 /* 14. Find the Vertical frame frequency:
435 *
436 * [V FRAME RATE] = (IF([INT RQD?]="y", [V FIELD RATE]/2, [V FIELD RATE]))
437 *
438 * N.B. that the result here is in mHz.
439 */
440
441 v_frame_rate = (flags & VESAGTF_FLAG_ILACE0x0001) ?
442 v_field_rate / 2 : v_field_rate;
443
444 print_value(14, "[V FRAME RATE]", v_frame_rate);
445
446
447 /* 15. Find number of pixels in left margin:
448 * 16. Find number of pixels in right margin:
449 *
450 * [LEFT MARGIN (PIXELS)] = (IF( [MARGINS RQD?]="Y",
451 * (ROUND( ([H PIXELS RND] * [MARGIN%] / 100 /
452 * [CELL GRAN RND]),0)) * [CELL GRAN RND],
453 * 0))
454 *
455 * Again, we deal with margin percentages as PPT (parts per thousand).
456 * And the calculations for left and right are the same.
457 */
458
459 left_margin = right_margin = (flags & VESAGTF_FLAG_MARGINS0x0002) ?
460 DIVIDE(DIVIDE(h_pixels * params->margin_ppt, 1000),((((((h_pixels * params->margin_ppt) + ((1000) / 2)) / (1000
))) + ((8) / 2)) / (8))
461 CELL_GRAN)((((((h_pixels * params->margin_ppt) + ((1000) / 2)) / (1000
))) + ((8) / 2)) / (8)) * CELL_GRAN8 : 0;
462
463 print_value(15, "[LEFT MARGIN (PIXELS)]", left_margin);
464 print_value(16, "[RIGHT MARGIN (PIXELS)]", right_margin);
465
466
467 /* 17. Find total number of active pixels in image and left and right
468 * margins:
469 *
470 * [TOTAL ACTIVE PIXELS] = [H PIXELS RND] + [LEFT MARGIN (PIXELS)] +
471 * [RIGHT MARGIN (PIXELS)]
472 */
473
474 total_active_pixels = h_pixels + left_margin + right_margin;
475
476 print_value(17, "[TOTAL ACTIVE PIXELS]", total_active_pixels);
477
478
479 /* 18. Find the ideal blanking duty cycle from the blanking duty cycle
480 * equation:
481 *
482 * [IDEAL DUTY CYCLE] = [C'] - ([M']*[H PERIOD]/1000)
483 *
484 * However, we have modified values for [C'] as [256*C'] and
485 * [M'] as [256*M']. Again the idea here is to get good scaling.
486 * We use 256 as the factor to make the math fast.
487 *
488 * Note that this means that we have to scale it appropriately in
489 * later calculations.
490 *
491 * The ending result is that our ideal_duty_cycle is 256000x larger
492 * than the duty cycle used by VESA. But again, this reduces error
493 * propagation.
494 */
495
496 ideal_duty_cycle =
497 ((C_PRIME256(params)(((params->C - params->J) * params->K) + (params->
J * 256)) * 1000) -
498 (M_PRIME256(params)(params->K * params->M) * h_period / 1000000));
499
500 print_value(18, "[IDEAL DUTY CYCLE]", ideal_duty_cycle);
501
502
503 /* 19. Find the number of pixels in the blanking time to the nearest
504 * double character cell:
505 *
506 * [H BLANK (PIXELS)] = (ROUND(([TOTAL ACTIVE PIXELS] *
507 * [IDEAL DUTY CYCLE] /
508 * (100-[IDEAL DUTY CYCLE]) /
509 * (2*[CELL GRAN RND])), 0))
510 * * (2*[CELL GRAN RND])
511 *
512 * Of course, we adjust to make this rounding work in integer math.
513 */
514
515 h_blank = DIVIDE(DIVIDE(total_active_pixels * ideal_duty_cycle,((((((total_active_pixels * ideal_duty_cycle) + (((256000 * 100ULL
) - ideal_duty_cycle) / 2)) / ((256000 * 100ULL) - ideal_duty_cycle
))) + ((2 * 8) / 2)) / (2 * 8))
516 (256000 * 100ULL) - ideal_duty_cycle),((((((total_active_pixels * ideal_duty_cycle) + (((256000 * 100ULL
) - ideal_duty_cycle) / 2)) / ((256000 * 100ULL) - ideal_duty_cycle
))) + ((2 * 8) / 2)) / (2 * 8))
517 2 * CELL_GRAN)((((((total_active_pixels * ideal_duty_cycle) + (((256000 * 100ULL
) - ideal_duty_cycle) / 2)) / ((256000 * 100ULL) - ideal_duty_cycle
))) + ((2 * 8) / 2)) / (2 * 8)) * (2 * CELL_GRAN8);
518
519 print_value(19, "[H BLANK (PIXELS)]", h_blank);
520
521
522 /* 20. Find total number of pixels:
523 *
524 * [TOTAL PIXELS] = [TOTAL ACTIVE PIXELS] + [H BLANK (PIXELS)]
525 */
526
527 total_pixels = total_active_pixels + h_blank;
528
529 print_value(20, "[TOTAL PIXELS]", total_pixels);
530
531
532 /* 21. Find pixel clock frequency:
533 *
534 * [PIXEL FREQ] = [TOTAL PIXELS] / [H PERIOD]
535 *
536 * We calculate this in Hz rather than MHz, to get a value that
537 * is usable with integer math. Recall that the [H PERIOD] is in
538 * nsec.
539 */
540
541 pixel_freq = DIVIDE(total_pixels * 1000000, DIVIDE(h_period, 1000))(((total_pixels * 1000000) + (((((h_period) + ((1000) / 2)) /
(1000))) / 2)) / ((((h_period) + ((1000) / 2)) / (1000))));
542
543 print_value(21, "[PIXEL FREQ]", pixel_freq);
544
545
546 /* 22. Find horizontal frequency:
547 *
548 * [H FREQ] = 1000 / [H PERIOD]
549 *
550 * I've ifdef'd this out, because we don't need it for any of
551 * our calculations.
552 * We calculate this in Hz rather than kHz, to avoid rounding
553 * errors. Recall that the [H PERIOD] is in usec.
554 */
555
556#ifdef GTFDEBUG
557 h_freq = 1000000000 / h_period;
558
559 print_value(22, "[H FREQ]", h_freq);
560#endif
561
562
563
564 /* Stage 1 computations are now complete; I should really pass
565 the results to another function and do the Stage 2
566 computations, but I only need a few more values so I'll just
567 append the computations here for now */
568
569
570
571 /* 17. Find the number of pixels in the horizontal sync period:
572 *
573 * [H SYNC (PIXELS)] =(ROUND(([H SYNC%] / 100 * [TOTAL PIXELS] /
574 * [CELL GRAN RND]),0))*[CELL GRAN RND]
575 *
576 * Rewriting for integer math:
577 *
578 * [H SYNC (PIXELS)]=(ROUND((H SYNC%] * [TOTAL PIXELS] / 100 /
579 * [CELL GRAN RND),0))*[CELL GRAN RND]
580 */
581
582 h_sync = DIVIDE(((params->hsync_pct * total_pixels) / 100), CELL_GRAN)(((((params->hsync_pct * total_pixels) / 100)) + ((8) / 2)
) / (8)) *
583 CELL_GRAN8;
584
585 print_value(17, "[H SYNC (PIXELS)]", h_sync);
586
587
588 /* 18. Find the number of pixels in the horizontal front porch period:
589 *
590 * [H FRONT PORCH (PIXELS)] = ([H BLANK (PIXELS)]/2)-[H SYNC (PIXELS)]
591 *
592 * Note that h_blank is always an even number of characters (i.e.
593 * h_blank % (CELL_GRAN * 2) == 0)
594 */
595
596 h_front_porch = (h_blank / 2) - h_sync;
597
598 print_value(18, "[H FRONT PORCH (PIXELS)]", h_front_porch);
599
600
601 /* 36. Find the number of lines in the odd front porch period:
602 *
603 * [V ODD FRONT PORCH(LINES)]=([MIN PORCH RND]+[INTERLACE])
604 *
605 * Adjusting for the fact that the interlace is scaled:
606 *
607 * [V ODD FRONT PORCH(LINES)]=(([MIN PORCH RND] * 2) + [2*INTERLACE]) / 2
608 */
609
610 v_odd_front_porch_lines = ((2 * params->min_porch) + interlace) / 2;
611
612 print_value(36, "[V ODD FRONT PORCH(LINES)]", v_odd_front_porch_lines);
613
614
615 /* finally, pack the results in the mode struct */
616
617 vmp->hsync_start = h_pixels + h_front_porch;
618 vmp->hsync_end = vmp->hsync_start + h_sync;
619 vmp->htotal = total_pixels;
620 vmp->hdisplay = h_pixels;
621
622 vmp->vsync_start = v_lines + v_odd_front_porch_lines;
623 vmp->vsync_end = vmp->vsync_start + params->vsync_rqd;
624 vmp->vtotal = total_v_lines;
625 vmp->vdisplay = v_lines;
626
627 vmp->dot_clock = pixel_freq;
628
629}
630
631void
632vesagtf_mode(unsigned x, unsigned y, unsigned refresh, struct videomode *vmp)
633{
634 struct vesagtf_params params;
635
636 params.margin_ppt = VESAGTF_MARGIN_PPT18;
637 params.min_porch = VESAGTF_MIN_PORCH1;
638 params.vsync_rqd = VESAGTF_VSYNC_RQD3;
639 params.hsync_pct = VESAGTF_HSYNC_PCT8;
640 params.min_vsbp = VESAGTF_MIN_VSBP550;
641 params.M = VESAGTF_M600;
642 params.C = VESAGTF_C40;
643 params.K = VESAGTF_K128;
644 params.J = VESAGTF_J20;
645
646 vesagtf_mode_params(x, y, refresh, &params, 0, vmp);
647}
648
649/*
650 * The tidbit here is so that you can compile this file as a
651 * standalone user program to generate X11 modelines using VESA GTF.
652 * This also allows for testing of the code itself, without
653 * necessitating a full kernel recompile.
654 */
655
656/* print_xf86_mode() - print the XFree86 modeline, given mode timings. */
657
658#ifndef _KERNEL1
659void
660print_xf86_mode (struct videomode *vmp)
661{
662 float vf, hf;
663
664 hf = 1000.0 * vmp->dot_clock / vmp->htotal;
665 vf = 1.0 * hf / vmp->vtotal;
666
667 printf("\n");
668 printf(" # %dx%d @ %.2f Hz (GTF) hsync: %.2f kHz; pclk: %.2f MHz\n",
669 vmp->hdisplay, vmp->vdisplay, vf, hf, vmp->dot_clock / 1000.0);
670
671 printf(" Modeline \"%dx%d_%.2f\" %.2f"
672 " %d %d %d %d"
673 " %d %d %d %d"
674 " -HSync +Vsync\n\n",
675 vmp->hdisplay, vmp->vdisplay, vf, (vmp->dot_clock / 1000.0),
676 vmp->hdisplay, vmp->hsync_start, vmp->hsync_end, vmp->htotal,
677 vmp->vdisplay, vmp->vsync_start, vmp->vsync_end, vmp->vtotal);
678}
679
680int
681main (int argc, char *argv[])
682{
683 struct videomode m;
684
685 if (argc != 4) {
686 printf("usage: %s x y refresh\n", argv[0]);
687 exit(1);
688 }
689
690 vesagtf_mode(atoi(argv[1]), atoi(argv[2]), atoi(argv[3]), &m);
691
692 print_xf86_mode(&m);
693
694 return 0;
695
696}
697#endif