* Copyright © 2007-2008 Intel Corporation
* Jesse Barnes <jesse.barnes@intel.com>
* Copyright 2005-2006 Luc Verhaegen
+ * Copyright (c) 2001, Andy Ritger aritger@nvidia.com
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
}
EXPORT_SYMBOL(drm_cvt_mode);
+/**
+ * drm_gtf_mode - create the modeline based on GTF algorithm
+ *
+ * @dev :drm device
+ * @hdisplay :hdisplay size
+ * @vdisplay :vdisplay size
+ * @vrefresh :vrefresh rate.
+ * @interlaced :whether the interlace is supported
+ * @margins :whether the margin is supported
+ *
+ * LOCKING.
+ * none.
+ *
+ * return the modeline based on GTF algorithm
+ *
+ * This function is to create the modeline based on the GTF algorithm.
+ * Generalized Timing Formula is derived from:
+ * GTF Spreadsheet by Andy Morrish (1/5/97)
+ * available at http://www.vesa.org
+ *
+ * And it is copied from the file of xserver/hw/xfree86/modes/xf86gtf.c.
+ * What I have done is to translate it by using integer calculation.
+ * I also refer to the function of fb_get_mode in the file of
+ * drivers/video/fbmon.c
+ */
+struct drm_display_mode *drm_gtf_mode(struct drm_device *dev, int hdisplay,
+ int vdisplay, int vrefresh,
+ bool interlaced, int margins)
+{
+ /* 1) top/bottom margin size (% of height) - default: 1.8, */
+#define GTF_MARGIN_PERCENTAGE 18
+ /* 2) character cell horizontal granularity (pixels) - default 8 */
+#define GTF_CELL_GRAN 8
+ /* 3) Minimum vertical porch (lines) - default 3 */
+#define GTF_MIN_V_PORCH 1
+ /* width of vsync in lines */
+#define V_SYNC_RQD 3
+ /* width of hsync as % of total line */
+#define H_SYNC_PERCENT 8
+ /* min time of vsync + back porch (microsec) */
+#define MIN_VSYNC_PLUS_BP 550
+ /* blanking formula gradient */
+#define GTF_M 600
+ /* blanking formula offset */
+#define GTF_C 40
+ /* blanking formula scaling factor */
+#define GTF_K 128
+ /* blanking formula scaling factor */
+#define GTF_J 20
+ /* C' and M' are part of the Blanking Duty Cycle computation */
+#define GTF_C_PRIME (((GTF_C - GTF_J) * GTF_K / 256) + GTF_J)
+#define GTF_M_PRIME (GTF_K * GTF_M / 256)
+ struct drm_display_mode *drm_mode;
+ unsigned int hdisplay_rnd, vdisplay_rnd, vfieldrate_rqd;
+ int top_margin, bottom_margin;
+ int interlace;
+ unsigned int hfreq_est;
+ int vsync_plus_bp, vback_porch;
+ unsigned int vtotal_lines, vfieldrate_est, hperiod;
+ unsigned int vfield_rate, vframe_rate;
+ int left_margin, right_margin;
+ unsigned int total_active_pixels, ideal_duty_cycle;
+ unsigned int hblank, total_pixels, pixel_freq;
+ int hsync, hfront_porch, vodd_front_porch_lines;
+ unsigned int tmp1, tmp2;
+
+ drm_mode = drm_mode_create(dev);
+ if (!drm_mode)
+ return NULL;
+
+ /* 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:
+ */
+ hdisplay_rnd = (hdisplay + GTF_CELL_GRAN / 2) / GTF_CELL_GRAN;
+ hdisplay_rnd = hdisplay_rnd * GTF_CELL_GRAN;
+
+ /* 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.
+ */
+ if (interlaced)
+ vdisplay_rnd = vdisplay / 2;
+ else
+ vdisplay_rnd = vdisplay;
+
+ /* 3. Find the frame rate required: */
+ if (interlaced)
+ vfieldrate_rqd = vrefresh * 2;
+ else
+ vfieldrate_rqd = vrefresh;
+
+ /* 4. Find number of lines in Top margin: */
+ top_margin = 0;
+ if (margins)
+ top_margin = (vdisplay_rnd * GTF_MARGIN_PERCENTAGE + 500) /
+ 1000;
+ /* 5. Find number of lines in bottom margin: */
+ bottom_margin = top_margin;
+
+ /* 6. If interlace is required, then set variable interlace: */
+ if (interlaced)
+ interlace = 1;
+ else
+ interlace = 0;
+
+ /* 7. Estimate the Horizontal frequency */
+ {
+ tmp1 = (1000000 - MIN_VSYNC_PLUS_BP * vfieldrate_rqd) / 500;
+ tmp2 = (vdisplay_rnd + 2 * top_margin + GTF_MIN_V_PORCH) *
+ 2 + interlace;
+ hfreq_est = (tmp2 * 1000 * vfieldrate_rqd) / tmp1;
+ }
+
+ /* 8. Find the number of lines in V sync + back porch */
+ /* [V SYNC+BP] = RINT(([MIN VSYNC+BP] * hfreq_est / 1000000)) */
+ vsync_plus_bp = MIN_VSYNC_PLUS_BP * hfreq_est / 1000;
+ vsync_plus_bp = (vsync_plus_bp + 500) / 1000;
+ /* 9. Find the number of lines in V back porch alone: */
+ vback_porch = vsync_plus_bp - V_SYNC_RQD;
+ /* 10. Find the total number of lines in Vertical field period: */
+ vtotal_lines = vdisplay_rnd + top_margin + bottom_margin +
+ vsync_plus_bp + GTF_MIN_V_PORCH;
+ /* 11. Estimate the Vertical field frequency: */
+ vfieldrate_est = hfreq_est / vtotal_lines;
+ /* 12. Find the actual horizontal period: */
+ hperiod = 1000000 / (vfieldrate_rqd * vtotal_lines);
+
+ /* 13. Find the actual Vertical field frequency: */
+ vfield_rate = hfreq_est / vtotal_lines;
+ /* 14. Find the Vertical frame frequency: */
+ if (interlaced)
+ vframe_rate = vfield_rate / 2;
+ else
+ vframe_rate = vfield_rate;
+ /* 15. Find number of pixels in left margin: */
+ if (margins)
+ left_margin = (hdisplay_rnd * GTF_MARGIN_PERCENTAGE + 500) /
+ 1000;
+ else
+ left_margin = 0;
+
+ /* 16.Find number of pixels in right margin: */
+ right_margin = left_margin;
+ /* 17.Find total number of active pixels in image and left and right */
+ total_active_pixels = hdisplay_rnd + left_margin + right_margin;
+ /* 18.Find the ideal blanking duty cycle from blanking duty cycle */
+ ideal_duty_cycle = GTF_C_PRIME * 1000 -
+ (GTF_M_PRIME * 1000000 / hfreq_est);
+ /* 19.Find the number of pixels in the blanking time to the nearest
+ * double character cell: */
+ hblank = total_active_pixels * ideal_duty_cycle /
+ (100000 - ideal_duty_cycle);
+ hblank = (hblank + GTF_CELL_GRAN) / (2 * GTF_CELL_GRAN);
+ hblank = hblank * 2 * GTF_CELL_GRAN;
+ /* 20.Find total number of pixels: */
+ total_pixels = total_active_pixels + hblank;
+ /* 21.Find pixel clock frequency: */
+ pixel_freq = total_pixels * hfreq_est / 1000;
+ /* 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: */
+ hsync = H_SYNC_PERCENT * total_pixels / 100;
+ hsync = (hsync + GTF_CELL_GRAN / 2) / GTF_CELL_GRAN;
+ hsync = hsync * GTF_CELL_GRAN;
+ /* 18. Find the number of pixels in horizontal front porch period */
+ hfront_porch = hblank / 2 - hsync;
+ /* 36. Find the number of lines in the odd front porch period: */
+ vodd_front_porch_lines = GTF_MIN_V_PORCH ;
+
+ /* finally, pack the results in the mode struct */
+ drm_mode->hdisplay = hdisplay_rnd;
+ drm_mode->hsync_start = hdisplay_rnd + hfront_porch;
+ drm_mode->hsync_end = drm_mode->hsync_start + hsync;
+ drm_mode->htotal = total_pixels;
+ drm_mode->vdisplay = vdisplay_rnd;
+ drm_mode->vsync_start = vdisplay_rnd + vodd_front_porch_lines;
+ drm_mode->vsync_end = drm_mode->vsync_start + V_SYNC_RQD;
+ drm_mode->vtotal = vtotal_lines;
+
+ drm_mode->clock = pixel_freq;
+
+ drm_mode_set_name(drm_mode);
+ drm_mode->flags = DRM_MODE_FLAG_NHSYNC | DRM_MODE_FLAG_PVSYNC;
+
+ if (interlaced) {
+ drm_mode->vtotal *= 2;
+ drm_mode->flags |= DRM_MODE_FLAG_INTERLACE;
+ }
+
+ return drm_mode;
+}
+EXPORT_SYMBOL(drm_gtf_mode);
/**
* drm_mode_set_name - set the name on a mode
* @mode: name will be set in this mode
projects / GitHub / MotorolaMobilityLLC / kernel-slsi.git / commitdiff