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Diffstat (limited to 'backend/drm/cvt.c')
| -rw-r--r-- | backend/drm/cvt.c | 269 |
1 files changed, 269 insertions, 0 deletions
diff --git a/backend/drm/cvt.c b/backend/drm/cvt.c new file mode 100644 index 00000000..40f156b7 --- /dev/null +++ b/backend/drm/cvt.c @@ -0,0 +1,269 @@ +/* + * Copyright 2005-2006 Luc Verhaegen. + * + * 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. + */ + +#include "backend/drm/cvt.h" + +/* top/bottom margin size (% of height) - default: 1.8 */ +#define CVT_MARGIN_PERCENTAGE 1.8 + +/* character cell horizontal granularity (pixels) - default 8 */ +#define CVT_H_GRANULARITY 8 + +/* Minimum vertical porch (lines) - default 3 */ +#define CVT_MIN_V_PORCH 3 + +/* Minimum number of vertical back porch lines - default 6 */ +#define CVT_MIN_V_BPORCH 6 + +/* Pixel clock step (kHz) */ +#define CVT_CLOCK_STEP 250 + +/* Minimum time of vertical sync + back porch interval (µs) + * default 550.0 */ +#define CVT_MIN_VSYNC_BP 550.0 + +/* Nominal hsync width (% of line period) - default 8 */ +#define CVT_HSYNC_PERCENTAGE 8 + +/* 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 + +/* 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 + +/* + * 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). + * + * This function is borrowed from xorg-xserver's xf86CVTmode. + */ +void generate_cvt_mode(drmModeModeInfo *mode, 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 */ + + /* CVT default is 60.0Hz */ + if (!vrefresh) { + vrefresh = 60.0; + } + + /* 1. Required field rate */ + if (interlaced) { + vfield_rate = vrefresh * 2; + } else { + vfield_rate = vrefresh; + } + + /* 2. Horizontal pixels */ + hdisplay_rnd = hdisplay - (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->hdisplay = hdisplay_rnd + 2 * hmargin; + + /* 5. Find number of lines per field */ + if (interlaced) { + vdisplay_rnd = vdisplay / 2; + } else { + vdisplay_rnd = 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->vdisplay = vdisplay + 2 * vmargin; + + /* 7. interlace */ + if (interlaced) { + interlace = 0.5; + } else { + interlace = 0.0; + } + + /* Determine vsync Width from aspect ratio */ + if (!(vdisplay % 3) && ((vdisplay * 4 / 3) == hdisplay)) { + vsync = 4; + } else if (!(vdisplay % 9) && ((vdisplay * 16 / 9) == hdisplay)) { + vsync = 5; + } else if (!(vdisplay % 10) && ((vdisplay * 16 / 10) == hdisplay)) { + vsync = 6; + } else if (!(vdisplay % 4) && ((vdisplay * 5 / 4) == hdisplay)) { + vsync = 7; + } else if (!(vdisplay % 9) && ((vdisplay * 15 / 9) == hdisplay)) { + vsync = 7; + } else { /* Custom */ + vsync = 10; + } + + if (!reduced) { /* simplified GTF calculation */ + float hblank_percentage; + int vsync_and_back_porch, vblank_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 */ + vblank_porch = vsync_and_back_porch - vsync; + (void) vblank_porch; + + /* 11. Find total number of lines in vertical field */ + mode->vtotal = vdisplay_rnd + 2 * vmargin + vsync_and_back_porch + interlace + + CVT_MIN_V_PORCH; + + /* 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->hdisplay * hblank_percentage / (100.0 - hblank_percentage); + hblank -= hblank % (2 * CVT_H_GRANULARITY); + + /* 14. Find total number of pixels in a line. */ + mode->htotal = mode->hdisplay + hblank; + + /* Fill in hsync values */ + mode->hsync_end = mode->hdisplay + hblank / 2; + + mode->hsync_start = mode->hsync_end - + (mode->htotal * CVT_HSYNC_PERCENTAGE) / 100; + mode->hsync_start += CVT_H_GRANULARITY - + mode->hsync_start % CVT_H_GRANULARITY; + + /* Fill in vsync values */ + mode->vsync_start = mode->vdisplay + CVT_MIN_V_PORCH; + mode->vsync_end = mode->vsync_start + vsync; + } else { /* reduced blanking */ + int vbi_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 */ + vbi_lines = ((float) CVT_RB_MIN_VBLANK) / hperiod + 1; + + /* 10. Check if vertical blanking is sufficient */ + if (vbi_lines < (CVT_RB_VFPORCH + vsync + CVT_MIN_V_BPORCH)) { + vbi_lines = CVT_RB_VFPORCH + vsync + CVT_MIN_V_BPORCH; + } + + /* 11. Find total number of lines in vertical field */ + mode->vtotal = vdisplay_rnd + 2 * vmargin + interlace + vbi_lines; + + /* 12. Find total number of pixels in a line */ + mode->htotal = mode->hdisplay + CVT_RB_H_BLANK; + + /* Fill in hsync values */ + mode->hsync_end = mode->hdisplay + CVT_RB_H_BLANK / 2; + mode->hsync_start = mode->hsync_end - CVT_RB_H_SYNC; + + /* Fill in vsync values */ + mode->vsync_start = mode->vdisplay + CVT_RB_VFPORCH; + mode->vsync_end = mode->vsync_start + vsync; + } + + /* 15/13. Find pixel clock frequency (kHz for xf86) */ + mode->clock = mode->htotal * 1000.0 / hperiod; + mode->clock -= mode->clock % CVT_CLOCK_STEP; + + /* 17/15. Find actual Field rate */ + mode->vrefresh = (1000.0 * ((float) mode->clock)) / + ((float) (mode->htotal * mode->vtotal)); + + /* 18/16. Find actual vertical frame frequency */ + /* ignore - just set the mode flag for interlaced */ + if (interlaced) { + mode->vtotal *= 2; + mode->flags |= DRM_MODE_FLAG_INTERLACE; + } + + snprintf(mode->name, sizeof(mode->name), "%dx%d", hdisplay, vdisplay); + + if (reduced) { + mode->flags |= DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_NVSYNC; + } else { + mode->flags |= DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_PVSYNC; + } +} |