1 // SPDX-License-Identifier: MIT
3 * Copyright © 2022-2023 Intel Corporation
9 #include "intel_display_types.h"
10 #include "intel_vblank.h"
11 #include "intel_vrr.h"
14 * This timing diagram depicts the video signal in and
15 * around the vertical blanking period.
17 * Assumptions about the fictitious mode used in this example:
19 * vsync_start = vblank_start + 1
20 * vsync_end = vblank_start + 2
21 * vtotal = vblank_start + 3
24 * latch double buffered registers
25 * increment frame counter (ctg+)
26 * generate start of vblank interrupt (gen4+)
29 * | generate frame start interrupt (aka. vblank interrupt) (gmch)
30 * | may be shifted forward 1-3 extra lines via TRANSCONF
33 * | | generate vsync interrupt
35 * ___xxxx___ ___xxxx___ ___xxxx___ ___xxxx___ ___xxxx___ ___xxxx
36 * . \hs/ . \hs/ \hs/ \hs/ . \hs/
37 * ----va---> <-----------------vb--------------------> <--------va-------------
39 * -vbs-----> <---vbs+1---> <---vbs+2---> <-----0-----> <-----1-----> <-----2--- (scanline counter gen2)
40 * -vbs-2---> <---vbs-1---> <---vbs-----> <---vbs+1---> <---vbs+2---> <-----0--- (scanline counter gen3+)
41 * -vbs-2---> <---vbs-2---> <---vbs-1---> <---vbs-----> <---vbs+1---> <---vbs+2- (scanline counter hsw+ hdmi)
43 * last visible pixel first visible pixel
44 * | increment frame counter (gen3/4)
45 * pixel counter = vblank_start * htotal pixel counter = 0 (gen3/4)
47 * x = horizontal active
48 * _ = horizontal blanking
49 * hs = horizontal sync
50 * va = vertical active
51 * vb = vertical blanking
53 * vbs = vblank_start (number)
56 * - most events happen at the start of horizontal sync
57 * - frame start happens at the start of horizontal blank, 1-4 lines
58 * (depending on TRANSCONF settings) after the start of vblank
59 * - gen3/4 pixel and frame counter are synchronized with the start
60 * of horizontal active on the first line of vertical active
64 * Called from drm generic code, passed a 'crtc', which we use as a pipe index.
66 u32 i915_get_vblank_counter(struct drm_crtc *crtc)
68 struct drm_i915_private *dev_priv = to_i915(crtc->dev);
69 struct drm_vblank_crtc *vblank = &dev_priv->drm.vblank[drm_crtc_index(crtc)];
70 const struct drm_display_mode *mode = &vblank->hwmode;
71 enum pipe pipe = to_intel_crtc(crtc)->pipe;
72 u32 pixel, vbl_start, hsync_start, htotal;
76 * On i965gm TV output the frame counter only works up to
77 * the point when we enable the TV encoder. After that the
78 * frame counter ceases to work and reads zero. We need a
79 * vblank wait before enabling the TV encoder and so we
80 * have to enable vblank interrupts while the frame counter
81 * is still in a working state. However the core vblank code
82 * does not like us returning non-zero frame counter values
83 * when we've told it that we don't have a working frame
84 * counter. Thus we must stop non-zero values leaking out.
86 if (!vblank->max_vblank_count)
89 htotal = mode->crtc_htotal;
90 hsync_start = mode->crtc_hsync_start;
91 vbl_start = mode->crtc_vblank_start;
92 if (mode->flags & DRM_MODE_FLAG_INTERLACE)
93 vbl_start = DIV_ROUND_UP(vbl_start, 2);
95 /* Convert to pixel count */
98 /* Start of vblank event occurs at start of hsync */
99 vbl_start -= htotal - hsync_start;
102 * High & low register fields aren't synchronized, so make sure
103 * we get a low value that's stable across two reads of the high
106 frame = intel_de_read64_2x32(dev_priv, PIPEFRAMEPIXEL(pipe), PIPEFRAME(pipe));
108 pixel = frame & PIPE_PIXEL_MASK;
109 frame = (frame >> PIPE_FRAME_LOW_SHIFT) & 0xffffff;
112 * The frame counter increments at beginning of active.
113 * Cook up a vblank counter by also checking the pixel
114 * counter against vblank start.
116 return (frame + (pixel >= vbl_start)) & 0xffffff;
119 u32 g4x_get_vblank_counter(struct drm_crtc *crtc)
121 struct drm_i915_private *dev_priv = to_i915(crtc->dev);
122 struct drm_vblank_crtc *vblank = &dev_priv->drm.vblank[drm_crtc_index(crtc)];
123 enum pipe pipe = to_intel_crtc(crtc)->pipe;
125 if (!vblank->max_vblank_count)
128 return intel_de_read(dev_priv, PIPE_FRMCOUNT_G4X(pipe));
131 static u32 intel_crtc_scanlines_since_frame_timestamp(struct intel_crtc *crtc)
133 struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
134 struct drm_vblank_crtc *vblank =
135 &crtc->base.dev->vblank[drm_crtc_index(&crtc->base)];
136 const struct drm_display_mode *mode = &vblank->hwmode;
137 u32 htotal = mode->crtc_htotal;
138 u32 clock = mode->crtc_clock;
139 u32 scan_prev_time, scan_curr_time, scan_post_time;
142 * To avoid the race condition where we might cross into the
143 * next vblank just between the PIPE_FRMTMSTMP and TIMESTAMP_CTR
144 * reads. We make sure we read PIPE_FRMTMSTMP and TIMESTAMP_CTR
145 * during the same frame.
149 * This field provides read back of the display
150 * pipe frame time stamp. The time stamp value
151 * is sampled at every start of vertical blank.
153 scan_prev_time = intel_de_read_fw(dev_priv,
154 PIPE_FRMTMSTMP(crtc->pipe));
157 * The TIMESTAMP_CTR register has the current
160 scan_curr_time = intel_de_read_fw(dev_priv, IVB_TIMESTAMP_CTR);
162 scan_post_time = intel_de_read_fw(dev_priv,
163 PIPE_FRMTMSTMP(crtc->pipe));
164 } while (scan_post_time != scan_prev_time);
166 return div_u64(mul_u32_u32(scan_curr_time - scan_prev_time,
167 clock), 1000 * htotal);
171 * On certain encoders on certain platforms, pipe
172 * scanline register will not work to get the scanline,
173 * since the timings are driven from the PORT or issues
174 * with scanline register updates.
175 * This function will use Framestamp and current
176 * timestamp registers to calculate the scanline.
178 static u32 __intel_get_crtc_scanline_from_timestamp(struct intel_crtc *crtc)
180 struct drm_vblank_crtc *vblank =
181 &crtc->base.dev->vblank[drm_crtc_index(&crtc->base)];
182 const struct drm_display_mode *mode = &vblank->hwmode;
183 u32 vblank_start = mode->crtc_vblank_start;
184 u32 vtotal = mode->crtc_vtotal;
187 scanline = intel_crtc_scanlines_since_frame_timestamp(crtc);
188 scanline = min(scanline, vtotal - 1);
189 scanline = (scanline + vblank_start) % vtotal;
195 * intel_de_read_fw(), only for fast reads of display block, no need for
198 static int __intel_get_crtc_scanline(struct intel_crtc *crtc)
200 struct drm_device *dev = crtc->base.dev;
201 struct drm_i915_private *dev_priv = to_i915(dev);
202 const struct drm_display_mode *mode;
203 struct drm_vblank_crtc *vblank;
204 enum pipe pipe = crtc->pipe;
205 int position, vtotal;
210 vblank = &crtc->base.dev->vblank[drm_crtc_index(&crtc->base)];
211 mode = &vblank->hwmode;
213 if (crtc->mode_flags & I915_MODE_FLAG_GET_SCANLINE_FROM_TIMESTAMP)
214 return __intel_get_crtc_scanline_from_timestamp(crtc);
216 vtotal = mode->crtc_vtotal;
217 if (mode->flags & DRM_MODE_FLAG_INTERLACE)
220 position = intel_de_read_fw(dev_priv, PIPEDSL(pipe)) & PIPEDSL_LINE_MASK;
223 * On HSW, the DSL reg (0x70000) appears to return 0 if we
224 * read it just before the start of vblank. So try it again
225 * so we don't accidentally end up spanning a vblank frame
226 * increment, causing the pipe_update_end() code to squak at us.
228 * The nature of this problem means we can't simply check the ISR
229 * bit and return the vblank start value; nor can we use the scanline
230 * debug register in the transcoder as it appears to have the same
231 * problem. We may need to extend this to include other platforms,
232 * but so far testing only shows the problem on HSW.
234 if (HAS_DDI(dev_priv) && !position) {
237 for (i = 0; i < 100; i++) {
239 temp = intel_de_read_fw(dev_priv, PIPEDSL(pipe)) & PIPEDSL_LINE_MASK;
240 if (temp != position) {
248 * See update_scanline_offset() for the details on the
249 * scanline_offset adjustment.
251 return (position + crtc->scanline_offset) % vtotal;
254 static bool i915_get_crtc_scanoutpos(struct drm_crtc *_crtc,
256 int *vpos, int *hpos,
257 ktime_t *stime, ktime_t *etime,
258 const struct drm_display_mode *mode)
260 struct drm_device *dev = _crtc->dev;
261 struct drm_i915_private *dev_priv = to_i915(dev);
262 struct intel_crtc *crtc = to_intel_crtc(_crtc);
263 enum pipe pipe = crtc->pipe;
265 int vbl_start, vbl_end, hsync_start, htotal, vtotal;
266 unsigned long irqflags;
267 bool use_scanline_counter = DISPLAY_VER(dev_priv) >= 5 ||
268 IS_G4X(dev_priv) || DISPLAY_VER(dev_priv) == 2 ||
269 crtc->mode_flags & I915_MODE_FLAG_USE_SCANLINE_COUNTER;
271 if (drm_WARN_ON(&dev_priv->drm, !mode->crtc_clock)) {
272 drm_dbg(&dev_priv->drm,
273 "trying to get scanoutpos for disabled pipe %c\n",
278 htotal = mode->crtc_htotal;
279 hsync_start = mode->crtc_hsync_start;
280 vtotal = mode->crtc_vtotal;
281 vbl_start = mode->crtc_vblank_start;
282 vbl_end = mode->crtc_vblank_end;
284 if (mode->flags & DRM_MODE_FLAG_INTERLACE) {
285 vbl_start = DIV_ROUND_UP(vbl_start, 2);
291 * Lock uncore.lock, as we will do multiple timing critical raw
292 * register reads, potentially with preemption disabled, so the
293 * following code must not block on uncore.lock.
295 spin_lock_irqsave(&dev_priv->uncore.lock, irqflags);
297 if (IS_ENABLED(CONFIG_PREEMPT_RT))
300 /* Get optional system timestamp before query. */
302 *stime = ktime_get();
304 if (crtc->mode_flags & I915_MODE_FLAG_VRR) {
305 int scanlines = intel_crtc_scanlines_since_frame_timestamp(crtc);
307 position = __intel_get_crtc_scanline(crtc);
310 * Already exiting vblank? If so, shift our position
311 * so it looks like we're already apporaching the full
312 * vblank end. This should make the generated timestamp
313 * more or less match when the active portion will start.
315 if (position >= vbl_start && scanlines < position)
316 position = min(crtc->vmax_vblank_start + scanlines, vtotal - 1);
317 } else if (use_scanline_counter) {
318 /* No obvious pixelcount register. Only query vertical
319 * scanout position from Display scan line register.
321 position = __intel_get_crtc_scanline(crtc);
324 * Have access to pixelcount since start of frame.
325 * We can split this into vertical and horizontal
328 position = (intel_de_read_fw(dev_priv, PIPEFRAMEPIXEL(pipe)) & PIPE_PIXEL_MASK) >> PIPE_PIXEL_SHIFT;
330 /* convert to pixel counts */
336 * In interlaced modes, the pixel counter counts all pixels,
337 * so one field will have htotal more pixels. In order to avoid
338 * the reported position from jumping backwards when the pixel
339 * counter is beyond the length of the shorter field, just
340 * clamp the position the length of the shorter field. This
341 * matches how the scanline counter based position works since
342 * the scanline counter doesn't count the two half lines.
344 position = min(position, vtotal - 1);
347 * Start of vblank interrupt is triggered at start of hsync,
348 * just prior to the first active line of vblank. However we
349 * consider lines to start at the leading edge of horizontal
350 * active. So, should we get here before we've crossed into
351 * the horizontal active of the first line in vblank, we would
352 * not set the DRM_SCANOUTPOS_INVBL flag. In order to fix that,
353 * always add htotal-hsync_start to the current pixel position.
355 position = (position + htotal - hsync_start) % vtotal;
358 /* Get optional system timestamp after query. */
360 *etime = ktime_get();
362 if (IS_ENABLED(CONFIG_PREEMPT_RT))
365 spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags);
368 * While in vblank, position will be negative
369 * counting up towards 0 at vbl_end. And outside
370 * vblank, position will be positive counting
373 if (position >= vbl_start)
376 position += vtotal - vbl_end;
378 if (use_scanline_counter) {
382 *vpos = position / htotal;
383 *hpos = position - (*vpos * htotal);
389 bool intel_crtc_get_vblank_timestamp(struct drm_crtc *crtc, int *max_error,
390 ktime_t *vblank_time, bool in_vblank_irq)
392 return drm_crtc_vblank_helper_get_vblank_timestamp_internal(
393 crtc, max_error, vblank_time, in_vblank_irq,
394 i915_get_crtc_scanoutpos);
397 int intel_get_crtc_scanline(struct intel_crtc *crtc)
399 struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
400 unsigned long irqflags;
403 spin_lock_irqsave(&dev_priv->uncore.lock, irqflags);
404 position = __intel_get_crtc_scanline(crtc);
405 spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags);
410 static bool pipe_scanline_is_moving(struct drm_i915_private *dev_priv,
413 i915_reg_t reg = PIPEDSL(pipe);
416 line1 = intel_de_read(dev_priv, reg) & PIPEDSL_LINE_MASK;
418 line2 = intel_de_read(dev_priv, reg) & PIPEDSL_LINE_MASK;
420 return line1 != line2;
423 static void wait_for_pipe_scanline_moving(struct intel_crtc *crtc, bool state)
425 struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
426 enum pipe pipe = crtc->pipe;
428 /* Wait for the display line to settle/start moving */
429 if (wait_for(pipe_scanline_is_moving(dev_priv, pipe) == state, 100))
430 drm_err(&dev_priv->drm,
431 "pipe %c scanline %s wait timed out\n",
432 pipe_name(pipe), str_on_off(state));
435 void intel_wait_for_pipe_scanline_stopped(struct intel_crtc *crtc)
437 wait_for_pipe_scanline_moving(crtc, false);
440 void intel_wait_for_pipe_scanline_moving(struct intel_crtc *crtc)
442 wait_for_pipe_scanline_moving(crtc, true);
445 static int intel_crtc_scanline_offset(const struct intel_crtc_state *crtc_state)
447 struct drm_i915_private *i915 = to_i915(crtc_state->uapi.crtc->dev);
448 const struct drm_display_mode *adjusted_mode = &crtc_state->hw.adjusted_mode;
451 * The scanline counter increments at the leading edge of hsync.
453 * On most platforms it starts counting from vtotal-1 on the
454 * first active line. That means the scanline counter value is
455 * always one less than what we would expect. Ie. just after
456 * start of vblank, which also occurs at start of hsync (on the
457 * last active line), the scanline counter will read vblank_start-1.
459 * On gen2 the scanline counter starts counting from 1 instead
460 * of vtotal-1, so we have to subtract one (or rather add vtotal-1
461 * to keep the value positive), instead of adding one.
463 * On HSW+ the behaviour of the scanline counter depends on the output
464 * type. For DP ports it behaves like most other platforms, but on HDMI
465 * there's an extra 1 line difference. So we need to add two instead of
468 * On VLV/CHV DSI the scanline counter would appear to increment
469 * approx. 1/3 of a scanline before start of vblank. Unfortunately
470 * that means we can't tell whether we're in vblank or not while
471 * we're on that particular line. We must still set scanline_offset
472 * to 1 so that the vblank timestamps come out correct when we query
473 * the scanline counter from within the vblank interrupt handler.
474 * However if queried just before the start of vblank we'll get an
475 * answer that's slightly in the future.
477 if (DISPLAY_VER(i915) == 2) {
480 vtotal = adjusted_mode->crtc_vtotal;
481 if (adjusted_mode->flags & DRM_MODE_FLAG_INTERLACE)
485 } else if (HAS_DDI(i915) && intel_crtc_has_type(crtc_state, INTEL_OUTPUT_HDMI)) {
492 void intel_crtc_update_active_timings(const struct intel_crtc_state *crtc_state,
495 struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
496 struct drm_i915_private *i915 = to_i915(crtc->base.dev);
497 u8 mode_flags = crtc_state->mode_flags;
498 struct drm_display_mode adjusted_mode;
499 int vmax_vblank_start = 0;
500 unsigned long irqflags;
502 drm_mode_init(&adjusted_mode, &crtc_state->hw.adjusted_mode);
505 drm_WARN_ON(&i915->drm, (mode_flags & I915_MODE_FLAG_VRR) == 0);
507 adjusted_mode.crtc_vtotal = crtc_state->vrr.vmax;
508 adjusted_mode.crtc_vblank_end = crtc_state->vrr.vmax;
509 adjusted_mode.crtc_vblank_start = intel_vrr_vmin_vblank_start(crtc_state);
510 vmax_vblank_start = intel_vrr_vmax_vblank_start(crtc_state);
512 mode_flags &= ~I915_MODE_FLAG_VRR;
516 * Belts and suspenders locking to guarantee everyone sees 100%
517 * consistent state during fastset seamless refresh rate changes.
519 * vblank_time_lock takes care of all drm_vblank.c stuff, and
520 * uncore.lock takes care of __intel_get_crtc_scanline() which
521 * may get called elsewhere as well.
523 * TODO maybe just protect everything (including
524 * __intel_get_crtc_scanline()) with vblank_time_lock?
525 * Need to audit everything to make sure it's safe.
527 spin_lock_irqsave(&i915->drm.vblank_time_lock, irqflags);
528 spin_lock(&i915->uncore.lock);
530 drm_calc_timestamping_constants(&crtc->base, &adjusted_mode);
532 crtc->vmax_vblank_start = vmax_vblank_start;
534 crtc->mode_flags = mode_flags;
536 crtc->scanline_offset = intel_crtc_scanline_offset(crtc_state);
538 spin_unlock(&i915->uncore.lock);
539 spin_unlock_irqrestore(&i915->drm.vblank_time_lock, irqflags);