drm/mode: add the GTF algorithm in kernel space
Add the GTF algorithm in kernel space. And this function can be called to generate the required modeline. I copied it from the file of xserver/hw/xfree86/modes/xf86gtf.c. What I have done is to translate it by using integer calculation. This is to avoid the float-point calculation in kernel space. At the same tie I also refer to the function of fb_get_mode in drivers/video/fbmon.c Signed-off-by: Zhao Yakui <yakui.zhao@intel.com> Signed-off-by: Dave Airlie <airlied@linux.ie>
This commit is contained in:
Zhao Yakui
Dave Airlie
parent
d782c3f95c
commit
26bbdadad3
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@ -9,6 +9,7 @@
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* Copyright © 2007-2008 Intel Corporation
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* Jesse Barnes <jesse.barnes@intel.com>
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* Copyright 2005-2006 Luc Verhaegen
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* Copyright (c) 2001, Andy Ritger aritger@nvidia.com
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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@ -280,6 +281,202 @@ struct drm_display_mode *drm_cvt_mode(struct drm_device *dev, int hdisplay,
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}
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EXPORT_SYMBOL(drm_cvt_mode);
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/**
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* drm_gtf_mode - create the modeline based on GTF algorithm
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*
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* @dev :drm device
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* @hdisplay :hdisplay size
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* @vdisplay :vdisplay size
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* @vrefresh :vrefresh rate.
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* @interlaced :whether the interlace is supported
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* @margins :whether the margin is supported
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*
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* LOCKING.
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* none.
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*
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* return the modeline based on GTF algorithm
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*
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* This function is to create the modeline based on the GTF algorithm.
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* Generalized Timing Formula is derived from:
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* GTF Spreadsheet by Andy Morrish (1/5/97)
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* available at http://www.vesa.org
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*
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* And it is copied from the file of xserver/hw/xfree86/modes/xf86gtf.c.
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* What I have done is to translate it by using integer calculation.
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* I also refer to the function of fb_get_mode in the file of
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* drivers/video/fbmon.c
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*/
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struct drm_display_mode *drm_gtf_mode(struct drm_device *dev, int hdisplay,
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int vdisplay, int vrefresh,
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bool interlaced, int margins)
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{
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/* 1) top/bottom margin size (% of height) - default: 1.8, */
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#define GTF_MARGIN_PERCENTAGE 18
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/* 2) character cell horizontal granularity (pixels) - default 8 */
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#define GTF_CELL_GRAN 8
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/* 3) Minimum vertical porch (lines) - default 3 */
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#define GTF_MIN_V_PORCH 1
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/* width of vsync in lines */
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#define V_SYNC_RQD 3
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/* width of hsync as % of total line */
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#define H_SYNC_PERCENT 8
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/* min time of vsync + back porch (microsec) */
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#define MIN_VSYNC_PLUS_BP 550
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/* blanking formula gradient */
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#define GTF_M 600
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/* blanking formula offset */
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#define GTF_C 40
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/* blanking formula scaling factor */
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#define GTF_K 128
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/* blanking formula scaling factor */
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#define GTF_J 20
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/* C' and M' are part of the Blanking Duty Cycle computation */
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#define GTF_C_PRIME (((GTF_C - GTF_J) * GTF_K / 256) + GTF_J)
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#define GTF_M_PRIME (GTF_K * GTF_M / 256)
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struct drm_display_mode *drm_mode;
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unsigned int hdisplay_rnd, vdisplay_rnd, vfieldrate_rqd;
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int top_margin, bottom_margin;
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int interlace;
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unsigned int hfreq_est;
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int vsync_plus_bp, vback_porch;
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unsigned int vtotal_lines, vfieldrate_est, hperiod;
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unsigned int vfield_rate, vframe_rate;
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int left_margin, right_margin;
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unsigned int total_active_pixels, ideal_duty_cycle;
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unsigned int hblank, total_pixels, pixel_freq;
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int hsync, hfront_porch, vodd_front_porch_lines;
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unsigned int tmp1, tmp2;
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drm_mode = drm_mode_create(dev);
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if (!drm_mode)
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return NULL;
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/* 1. In order to give correct results, the number of horizontal
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* pixels requested is first processed to ensure that it is divisible
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* by the character size, by rounding it to the nearest character
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* cell boundary:
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*/
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hdisplay_rnd = (hdisplay + GTF_CELL_GRAN / 2) / GTF_CELL_GRAN;
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hdisplay_rnd = hdisplay_rnd * GTF_CELL_GRAN;
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/* 2. If interlace is requested, the number of vertical lines assumed
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* by the calculation must be halved, as the computation calculates
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* the number of vertical lines per field.
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*/
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if (interlaced)
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vdisplay_rnd = vdisplay / 2;
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else
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vdisplay_rnd = vdisplay;
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/* 3. Find the frame rate required: */
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if (interlaced)
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vfieldrate_rqd = vrefresh * 2;
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else
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vfieldrate_rqd = vrefresh;
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/* 4. Find number of lines in Top margin: */
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top_margin = 0;
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if (margins)
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top_margin = (vdisplay_rnd * GTF_MARGIN_PERCENTAGE + 500) /
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1000;
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/* 5. Find number of lines in bottom margin: */
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bottom_margin = top_margin;
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/* 6. If interlace is required, then set variable interlace: */
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if (interlaced)
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interlace = 1;
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else
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interlace = 0;
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/* 7. Estimate the Horizontal frequency */
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{
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tmp1 = (1000000 - MIN_VSYNC_PLUS_BP * vfieldrate_rqd) / 500;
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tmp2 = (vdisplay_rnd + 2 * top_margin + GTF_MIN_V_PORCH) *
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2 + interlace;
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hfreq_est = (tmp2 * 1000 * vfieldrate_rqd) / tmp1;
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}
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/* 8. Find the number of lines in V sync + back porch */
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/* [V SYNC+BP] = RINT(([MIN VSYNC+BP] * hfreq_est / 1000000)) */
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vsync_plus_bp = MIN_VSYNC_PLUS_BP * hfreq_est / 1000;
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vsync_plus_bp = (vsync_plus_bp + 500) / 1000;
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/* 9. Find the number of lines in V back porch alone: */
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vback_porch = vsync_plus_bp - V_SYNC_RQD;
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/* 10. Find the total number of lines in Vertical field period: */
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vtotal_lines = vdisplay_rnd + top_margin + bottom_margin +
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vsync_plus_bp + GTF_MIN_V_PORCH;
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/* 11. Estimate the Vertical field frequency: */
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vfieldrate_est = hfreq_est / vtotal_lines;
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/* 12. Find the actual horizontal period: */
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hperiod = 1000000 / (vfieldrate_rqd * vtotal_lines);
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/* 13. Find the actual Vertical field frequency: */
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vfield_rate = hfreq_est / vtotal_lines;
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/* 14. Find the Vertical frame frequency: */
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if (interlaced)
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vframe_rate = vfield_rate / 2;
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else
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vframe_rate = vfield_rate;
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/* 15. Find number of pixels in left margin: */
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if (margins)
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left_margin = (hdisplay_rnd * GTF_MARGIN_PERCENTAGE + 500) /
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1000;
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else
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left_margin = 0;
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/* 16.Find number of pixels in right margin: */
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right_margin = left_margin;
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/* 17.Find total number of active pixels in image and left and right */
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total_active_pixels = hdisplay_rnd + left_margin + right_margin;
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/* 18.Find the ideal blanking duty cycle from blanking duty cycle */
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ideal_duty_cycle = GTF_C_PRIME * 1000 -
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(GTF_M_PRIME * 1000000 / hfreq_est);
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/* 19.Find the number of pixels in the blanking time to the nearest
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* double character cell: */
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hblank = total_active_pixels * ideal_duty_cycle /
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(100000 - ideal_duty_cycle);
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hblank = (hblank + GTF_CELL_GRAN) / (2 * GTF_CELL_GRAN);
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hblank = hblank * 2 * GTF_CELL_GRAN;
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/* 20.Find total number of pixels: */
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total_pixels = total_active_pixels + hblank;
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/* 21.Find pixel clock frequency: */
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pixel_freq = total_pixels * hfreq_est / 1000;
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/* Stage 1 computations are now complete; I should really pass
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* the results to another function and do the Stage 2 computations,
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* but I only need a few more values so I'll just append the
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* computations here for now */
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/* 17. Find the number of pixels in the horizontal sync period: */
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hsync = H_SYNC_PERCENT * total_pixels / 100;
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hsync = (hsync + GTF_CELL_GRAN / 2) / GTF_CELL_GRAN;
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hsync = hsync * GTF_CELL_GRAN;
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/* 18. Find the number of pixels in horizontal front porch period */
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hfront_porch = hblank / 2 - hsync;
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/* 36. Find the number of lines in the odd front porch period: */
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vodd_front_porch_lines = GTF_MIN_V_PORCH ;
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/* finally, pack the results in the mode struct */
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drm_mode->hdisplay = hdisplay_rnd;
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drm_mode->hsync_start = hdisplay_rnd + hfront_porch;
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drm_mode->hsync_end = drm_mode->hsync_start + hsync;
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drm_mode->htotal = total_pixels;
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drm_mode->vdisplay = vdisplay_rnd;
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drm_mode->vsync_start = vdisplay_rnd + vodd_front_porch_lines;
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drm_mode->vsync_end = drm_mode->vsync_start + V_SYNC_RQD;
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drm_mode->vtotal = vtotal_lines;
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drm_mode->clock = pixel_freq;
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drm_mode_set_name(drm_mode);
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drm_mode->flags = DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_PVSYNC;
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if (interlaced) {
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drm_mode->vtotal *= 2;
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drm_mode->flags |= DRM_MODE_FLAG_INTERLACE;
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}
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return drm_mode;
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}
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EXPORT_SYMBOL(drm_gtf_mode);
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/**
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* drm_mode_set_name - set the name on a mode
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* @mode: name will be set in this mode
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@ -739,4 +739,7 @@ extern bool drm_detect_hdmi_monitor(struct edid *edid);
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extern struct drm_display_mode *drm_cvt_mode(struct drm_device *dev,
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int hdisplay, int vdisplay, int vrefresh,
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bool reduced, bool interlaced);
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extern struct drm_display_mode *drm_gtf_mode(struct drm_device *dev,
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int hdisplay, int vdisplay, int vrefresh,
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bool interlaced, int margins);
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#endif /* __DRM_CRTC_H__ */
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