/* * Copyright 2005-2006 Luc Verhaegen. * Copyright © 2021 Red Hat, Inc. * * Permission is hereby granted, free of charge, to any person obtaining a * copy of this software and associated documentation files (the "Software"), * to deal in the Software without restriction, including without limitation * the rights to use, copy, modify, merge, publish, distribute, sublicense, * and/or sell copies of the Software, and to permit persons to whom the * Software is furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * 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 COPYRIGHT HOLDER(S) OR AUTHOR(S) 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. * */ /* Standalone VESA CVT standard timing modelines generator. */ #include #include #include #include /* * Generate a CVT standard mode from hdisplay, vdisplay and vrefresh. * * These calculations are stolen from the CVT calculation spreadsheet written * by Graham Loveridge. He seems to be claiming no copyright and there seems to * be no license attached to this. He apparently just wants to see his name * mentioned. * * This file can be found at http://www.vesa.org/Public/CVT/CVTd6r1.xls * * Comments and structure corresponds to the comments and structure of the xls. * This should ease importing of future changes to the standard (not very * likely though). * * About margins; i'm sure that they are to be the bit between HDisplay and * HBlankStart, HBlankEnd and HTotal, VDisplay and VBlankStart, VBlankEnd and * VTotal, where the overscan colour is shown. FB seems to call _all_ blanking * outside sync "margin" for some reason. Since we prefer seeing proper * blanking instead of the overscan colour, and since the Crtc* values will * probably get altered after us, we will disable margins altogether. With * these calculations, Margins will plainly expand H/VDisplay, and we don't * want that. -- libv * */ struct libxcvt_mode_info * libxcvt_gen_mode_info(int hdisplay, int vdisplay, float vrefresh, bool reduced, bool interlaced) { bool margins = false; float vfield_rate, hperiod; int hdisplay_rnd, hmargin; int vdisplay_rnd, vmargin, vsync; float interlace; /* Please rename this */ struct libxcvt_mode_info *mode_info; mode_info = calloc(1, sizeof *mode_info); if (!mode_info) return NULL; mode_info->hdisplay = hdisplay; mode_info->vdisplay = vdisplay; mode_info->vrefresh = vrefresh; /* 1) top/bottom margin size (% of height) - default: 1.8 */ #define CVT_MARGIN_PERCENTAGE 1.8 /* 2) character cell horizontal granularity (pixels) - default 8 */ #define CVT_H_GRANULARITY 8 /* 4) Minimum vertical porch (lines) - default 3 */ #define CVT_MIN_V_PORCH 3 /* 4) Minimum number of vertical back porch lines - default 6 */ #define CVT_MIN_V_BPORCH 6 /* Pixel Clock step (kHz) */ #define CVT_CLOCK_STEP 250 /* CVT default is 60.0Hz */ if (!mode_info->vrefresh) mode_info->vrefresh = 60.0; /* 1. Required field rate */ if (interlaced) vfield_rate = mode_info->vrefresh * 2; else vfield_rate = mode_info->vrefresh; /* 2. Horizontal pixels */ hdisplay_rnd = mode_info->hdisplay - (mode_info->hdisplay % CVT_H_GRANULARITY); /* 3. Determine left and right borders */ if (margins) { /* right margin is actually exactly the same as left */ hmargin = (((float) hdisplay_rnd) * CVT_MARGIN_PERCENTAGE / 100.0); hmargin -= hmargin % CVT_H_GRANULARITY; } else { hmargin = 0; } /* 4. Find total active pixels */ mode_info->hdisplay = hdisplay_rnd + 2 * hmargin; /* 5. Find number of lines per field */ if (interlaced) vdisplay_rnd = mode_info->vdisplay / 2; else vdisplay_rnd = mode_info->vdisplay; /* 6. Find top and bottom margins */ /* nope. */ if (margins) /* top and bottom margins are equal again. */ vmargin = (((float) vdisplay_rnd) * CVT_MARGIN_PERCENTAGE / 100.0); else vmargin = 0; mode_info->vdisplay = mode_info->vdisplay + 2 * vmargin; /* 7. interlace */ if (interlaced) interlace = 0.5; else interlace = 0.0; /* Determine vsync Width from aspect ratio */ if (!(mode_info->vdisplay % 3) && ((mode_info->vdisplay * 4 / 3) == mode_info->hdisplay)) vsync = 4; else if (!(mode_info->vdisplay % 9) && ((mode_info->vdisplay * 16 / 9) == mode_info->hdisplay)) vsync = 5; else if (!(mode_info->vdisplay % 10) && ((mode_info->vdisplay * 16 / 10) == mode_info->hdisplay)) vsync = 6; else if (!(mode_info->vdisplay % 4) && ((mode_info->vdisplay * 5 / 4) == mode_info->hdisplay)) vsync = 7; else if (!(mode_info->vdisplay % 9) && ((mode_info->vdisplay * 15 / 9) == mode_info->hdisplay)) vsync = 7; else /* Custom */ vsync = 10; if (!reduced) { /* simplified GTF calculation */ /* 4) Minimum time of vertical sync + back porch interval (µs) * default 550.0 */ #define CVT_MIN_VSYNC_BP 550.0 /* 3) Nominal HSync width (% of line period) - default 8 */ #define CVT_HSYNC_PERCENTAGE 8 float hblank_percentage; int vsync_and_back_porch, vback_porch; int hblank; /* 8. Estimated Horizontal period */ hperiod = ((float) (1000000.0 / vfield_rate - CVT_MIN_VSYNC_BP)) / (vdisplay_rnd + 2 * vmargin + CVT_MIN_V_PORCH + interlace); /* 9. Find number of lines in sync + backporch */ if (((int) (CVT_MIN_VSYNC_BP / hperiod) + 1) < (vsync + CVT_MIN_V_PORCH)) vsync_and_back_porch = vsync + CVT_MIN_V_PORCH; else vsync_and_back_porch = (int) (CVT_MIN_VSYNC_BP / hperiod) + 1; /* 10. Find number of lines in back porch */ vback_porch = vsync_and_back_porch - vsync; (void) vback_porch; /* 11. Find total number of lines in vertical field */ mode_info->vtotal = vdisplay_rnd + 2 * vmargin + vsync_and_back_porch + interlace + CVT_MIN_V_PORCH; /* 5) Definition of Horizontal blanking time limitation */ /* Gradient (%/kHz) - default 600 */ #define CVT_M_FACTOR 600 /* Offset (%) - default 40 */ #define CVT_C_FACTOR 40 /* Blanking time scaling factor - default 128 */ #define CVT_K_FACTOR 128 /* Scaling factor weighting - default 20 */ #define CVT_J_FACTOR 20 #define CVT_M_PRIME CVT_M_FACTOR * CVT_K_FACTOR / 256 #define CVT_C_PRIME (CVT_C_FACTOR - CVT_J_FACTOR) * CVT_K_FACTOR / 256 + \ CVT_J_FACTOR /* 12. Find ideal blanking duty cycle from formula */ hblank_percentage = CVT_C_PRIME - CVT_M_PRIME * hperiod / 1000.0; /* 13. Blanking time */ if (hblank_percentage < 20) hblank_percentage = 20; hblank = mode_info->hdisplay * hblank_percentage / (100.0 - hblank_percentage); hblank -= hblank % (2 * CVT_H_GRANULARITY); /* 14. Find total number of pixels in a line. */ mode_info->htotal = mode_info->hdisplay + hblank; /* Fill in HSync values */ mode_info->hsync_end = mode_info->hdisplay + hblank / 2; mode_info->hsync_start = mode_info->hsync_end - (mode_info->htotal * CVT_HSYNC_PERCENTAGE) / 100; mode_info->hsync_start += CVT_H_GRANULARITY - mode_info->hsync_start % CVT_H_GRANULARITY; /* Fill in vsync values */ mode_info->vsync_start = mode_info->vdisplay + CVT_MIN_V_PORCH; mode_info->vsync_end = mode_info->vsync_start + vsync; } else { /* reduced blanking */ /* Minimum vertical blanking interval time (µs) - default 460 */ #define CVT_RB_MIN_VBLANK 460.0 /* Fixed number of clocks for horizontal sync */ #define CVT_RB_H_SYNC 32.0 /* Fixed number of clocks for horizontal blanking */ #define CVT_RB_H_BLANK 160.0 /* Fixed number of lines for vertical front porch - default 3 */ #define CVT_RB_VFPORCH 3 int vblank_interval_lines; /* 8. Estimate Horizontal period. */ hperiod = ((float) (1000000.0 / vfield_rate - CVT_RB_MIN_VBLANK)) / (vdisplay_rnd + 2 * vmargin); /* 9. Find number of lines in vertical blanking */ vblank_interval_lines = ((float) CVT_RB_MIN_VBLANK) / hperiod + 1; /* 10. Check if vertical blanking is sufficient */ if (vblank_interval_lines < (CVT_RB_VFPORCH + vsync + CVT_MIN_V_BPORCH)) vblank_interval_lines = CVT_RB_VFPORCH + vsync + CVT_MIN_V_BPORCH; /* 11. Find total number of lines in vertical field */ mode_info->vtotal = vdisplay_rnd + 2 * vmargin + interlace + vblank_interval_lines; /* 12. Find total number of pixels in a line */ mode_info->htotal = mode_info->hdisplay + CVT_RB_H_BLANK; /* Fill in HSync values */ mode_info->hsync_end = mode_info->hdisplay + CVT_RB_H_BLANK / 2; mode_info->hsync_start = mode_info->hsync_end - CVT_RB_H_SYNC; /* Fill in vsync values */ mode_info->vsync_start = mode_info->vdisplay + CVT_RB_VFPORCH; mode_info->vsync_end = mode_info->vsync_start + vsync; } /* 15/13. Find pixel clock frequency (kHz for xf86) */ mode_info->dot_clock = mode_info->htotal * 1000.0 / hperiod; mode_info->dot_clock -= mode_info->dot_clock % CVT_CLOCK_STEP; /* 16/14. Find actual Horizontal Frequency (kHz) */ mode_info->hsync = ((float) mode_info->dot_clock) / ((float) mode_info->htotal); /* 17/15. Find actual Field rate */ mode_info->vrefresh = (1000.0 * ((float) mode_info->dot_clock)) / ((float) (mode_info->htotal * mode_info->vtotal)); /* 18/16. Find actual vertical frame frequency */ /* ignore - just set the mode flag for interlaced */ if (interlaced) mode_info->vtotal *= 2; if (reduced) mode_info->mode_flags |= LIBXCVT_MODE_FLAG_HSYNC_POSITIVE | LIBXCVT_MODE_FLAG_VSYNC_NEGATIVE; else mode_info->mode_flags |= LIBXCVT_MODE_FLAG_HSYNC_NEGATIVE | LIBXCVT_MODE_FLAG_VSYNC_POSITIVE; if (interlaced) mode_info->mode_flags |= LIBXCVT_MODE_FLAG_INTERLACE; /* FWXGA hack adapted from hw/xfree86/modes/xf86EdidModes.c, because you can't say 1366 */ if (mode_info->hdisplay == 1360 && mode_info->vdisplay == 768) { mode_info->hdisplay = 1366; mode_info->hsync_start--; mode_info->hsync_end--; } return mode_info; }