diff options
Diffstat (limited to 'drivers/gpu/drm/i915/display/intel_vblank.c')
| -rw-r--r-- | drivers/gpu/drm/i915/display/intel_vblank.c | 781 |
1 files changed, 781 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/display/intel_vblank.c b/drivers/gpu/drm/i915/display/intel_vblank.c new file mode 100644 index 000000000000..671f357c6563 --- /dev/null +++ b/drivers/gpu/drm/i915/display/intel_vblank.c @@ -0,0 +1,781 @@ +// SPDX-License-Identifier: MIT +/* + * Copyright © 2022-2023 Intel Corporation + */ + +#include <linux/iopoll.h> + +#include <drm/drm_print.h> +#include <drm/drm_vblank.h> + +#include "i915_drv.h" +#include "intel_color.h" +#include "intel_crtc.h" +#include "intel_de.h" +#include "intel_display_jiffies.h" +#include "intel_display_regs.h" +#include "intel_display_types.h" +#include "intel_display_utils.h" +#include "intel_vblank.h" +#include "intel_vrr.h" + +/* + * This timing diagram depicts the video signal in and + * around the vertical blanking period. + * + * Assumptions about the fictitious mode used in this example: + * vblank_start >= 3 + * vsync_start = vblank_start + 1 + * vsync_end = vblank_start + 2 + * vtotal = vblank_start + 3 + * + * start of vblank: + * latch double buffered registers + * increment frame counter (ctg+) + * generate start of vblank interrupt (gen4+) + * | + * | frame start: + * | generate frame start interrupt (aka. vblank interrupt) (gmch) + * | may be shifted forward 1-3 extra lines via TRANSCONF + * | | + * | | start of vsync: + * | | generate vsync interrupt + * | | | + * ___xxxx___ ___xxxx___ ___xxxx___ ___xxxx___ ___xxxx___ ___xxxx + * . \hs/ . \hs/ \hs/ \hs/ . \hs/ + * ----va---> <-----------------vb--------------------> <--------va------------- + * | | <----vs-----> | + * -vbs-----> <---vbs+1---> <---vbs+2---> <-----0-----> <-----1-----> <-----2--- (scanline counter gen2) + * -vbs-2---> <---vbs-1---> <---vbs-----> <---vbs+1---> <---vbs+2---> <-----0--- (scanline counter gen3+) + * -vbs-2---> <---vbs-2---> <---vbs-1---> <---vbs-----> <---vbs+1---> <---vbs+2- (scanline counter hsw+ hdmi) + * | | | + * last visible pixel first visible pixel + * | increment frame counter (gen3/4) + * pixel counter = vblank_start * htotal pixel counter = 0 (gen3/4) + * + * x = horizontal active + * _ = horizontal blanking + * hs = horizontal sync + * va = vertical active + * vb = vertical blanking + * vs = vertical sync + * vbs = vblank_start (number) + * + * Summary: + * - most events happen at the start of horizontal sync + * - frame start happens at the start of horizontal blank, 1-4 lines + * (depending on TRANSCONF settings) after the start of vblank + * - gen3/4 pixel and frame counter are synchronized with the start + * of horizontal active on the first line of vertical active + */ + +/* + * Called from drm generic code, passed a 'crtc', which we use as a pipe index. + */ +u32 i915_get_vblank_counter(struct drm_crtc *crtc) +{ + struct intel_display *display = to_intel_display(crtc->dev); + struct drm_vblank_crtc *vblank = drm_crtc_vblank_crtc(crtc); + const struct drm_display_mode *mode = &vblank->hwmode; + enum pipe pipe = to_intel_crtc(crtc)->pipe; + u32 pixel, vbl_start, hsync_start, htotal; + u64 frame; + + /* + * On i965gm TV output the frame counter only works up to + * the point when we enable the TV encoder. After that the + * frame counter ceases to work and reads zero. We need a + * vblank wait before enabling the TV encoder and so we + * have to enable vblank interrupts while the frame counter + * is still in a working state. However the core vblank code + * does not like us returning non-zero frame counter values + * when we've told it that we don't have a working frame + * counter. Thus we must stop non-zero values leaking out. + */ + if (!vblank->max_vblank_count) + return 0; + + htotal = mode->crtc_htotal; + hsync_start = mode->crtc_hsync_start; + vbl_start = intel_mode_vblank_start(mode); + + /* Convert to pixel count */ + vbl_start *= htotal; + + /* Start of vblank event occurs at start of hsync */ + vbl_start -= htotal - hsync_start; + + /* + * High & low register fields aren't synchronized, so make sure + * we get a low value that's stable across two reads of the high + * register. + */ + frame = intel_de_read64_2x32(display, PIPEFRAMEPIXEL(display, pipe), + PIPEFRAME(display, pipe)); + + pixel = frame & PIPE_PIXEL_MASK; + frame = (frame >> PIPE_FRAME_LOW_SHIFT) & 0xffffff; + + /* + * The frame counter increments at beginning of active. + * Cook up a vblank counter by also checking the pixel + * counter against vblank start. + */ + return (frame + (pixel >= vbl_start)) & 0xffffff; +} + +u32 g4x_get_vblank_counter(struct drm_crtc *crtc) +{ + struct intel_display *display = to_intel_display(crtc->dev); + struct drm_vblank_crtc *vblank = drm_crtc_vblank_crtc(crtc); + enum pipe pipe = to_intel_crtc(crtc)->pipe; + + if (!vblank->max_vblank_count) + return 0; + + return intel_de_read(display, PIPE_FRMCOUNT_G4X(display, pipe)); +} + +static u32 intel_crtc_scanlines_since_frame_timestamp(struct intel_crtc *crtc) +{ + struct intel_display *display = to_intel_display(crtc); + struct drm_vblank_crtc *vblank = drm_crtc_vblank_crtc(&crtc->base); + const struct drm_display_mode *mode = &vblank->hwmode; + u32 htotal = mode->crtc_htotal; + u32 clock = mode->crtc_clock; + u32 scan_prev_time, scan_curr_time, scan_post_time; + + /* + * To avoid the race condition where we might cross into the + * next vblank just between the PIPE_FRMTMSTMP and TIMESTAMP_CTR + * reads. We make sure we read PIPE_FRMTMSTMP and TIMESTAMP_CTR + * during the same frame. + */ + do { + /* + * This field provides read back of the display + * pipe frame time stamp. The time stamp value + * is sampled at every start of vertical blank. + */ + scan_prev_time = intel_de_read_fw(display, + PIPE_FRMTMSTMP(crtc->pipe)); + + /* + * The TIMESTAMP_CTR register has the current + * time stamp value. + */ + scan_curr_time = intel_de_read_fw(display, IVB_TIMESTAMP_CTR); + + scan_post_time = intel_de_read_fw(display, + PIPE_FRMTMSTMP(crtc->pipe)); + } while (scan_post_time != scan_prev_time); + + return div_u64(mul_u32_u32(scan_curr_time - scan_prev_time, + clock), 1000 * htotal); +} + +/* + * On certain encoders on certain platforms, pipe + * scanline register will not work to get the scanline, + * since the timings are driven from the PORT or issues + * with scanline register updates. + * This function will use Framestamp and current + * timestamp registers to calculate the scanline. + */ +static u32 __intel_get_crtc_scanline_from_timestamp(struct intel_crtc *crtc) +{ + struct drm_vblank_crtc *vblank = drm_crtc_vblank_crtc(&crtc->base); + const struct drm_display_mode *mode = &vblank->hwmode; + u32 vblank_start = mode->crtc_vblank_start; + u32 vtotal = mode->crtc_vtotal; + u32 scanline; + + scanline = intel_crtc_scanlines_since_frame_timestamp(crtc); + scanline = min(scanline, vtotal - 1); + scanline = (scanline + vblank_start) % vtotal; + + return scanline; +} + +int intel_crtc_scanline_offset(const struct intel_crtc_state *crtc_state) +{ + struct intel_display *display = to_intel_display(crtc_state); + + /* + * The scanline counter increments at the leading edge of hsync. + * + * On most platforms it starts counting from vtotal-1 on the + * first active line. That means the scanline counter value is + * always one less than what we would expect. Ie. just after + * start of vblank, which also occurs at start of hsync (on the + * last active line), the scanline counter will read vblank_start-1. + * + * On gen2 the scanline counter starts counting from 1 instead + * of vtotal-1, so we have to subtract one. + * + * On HSW+ the behaviour of the scanline counter depends on the output + * type. For DP ports it behaves like most other platforms, but on HDMI + * there's an extra 1 line difference. So we need to add two instead of + * one to the value. + * + * On VLV/CHV DSI the scanline counter would appear to increment + * approx. 1/3 of a scanline before start of vblank. Unfortunately + * that means we can't tell whether we're in vblank or not while + * we're on that particular line. We must still set scanline_offset + * to 1 so that the vblank timestamps come out correct when we query + * the scanline counter from within the vblank interrupt handler. + * However if queried just before the start of vblank we'll get an + * answer that's slightly in the future. + */ + if (DISPLAY_VER(display) >= 20 || display->platform.battlemage) + return 1; + else if (DISPLAY_VER(display) >= 9 || + display->platform.broadwell || display->platform.haswell) + return intel_crtc_has_type(crtc_state, INTEL_OUTPUT_HDMI) ? 2 : 1; + else if (DISPLAY_VER(display) >= 3) + return 1; + else + return -1; +} + +/* + * intel_de_read_fw(), only for fast reads of display block, no need for + * forcewake etc. + */ +static int __intel_get_crtc_scanline(struct intel_crtc *crtc) +{ + struct intel_display *display = to_intel_display(crtc); + struct drm_vblank_crtc *vblank = drm_crtc_vblank_crtc(&crtc->base); + const struct drm_display_mode *mode = &vblank->hwmode; + enum pipe pipe = crtc->pipe; + int position, vtotal; + + if (!crtc->active) + return 0; + + if (crtc->mode_flags & I915_MODE_FLAG_GET_SCANLINE_FROM_TIMESTAMP) + return __intel_get_crtc_scanline_from_timestamp(crtc); + + vtotal = intel_mode_vtotal(mode); + + position = intel_de_read_fw(display, PIPEDSL(display, pipe)) & PIPEDSL_LINE_MASK; + + /* + * On HSW, the DSL reg (0x70000) appears to return 0 if we + * read it just before the start of vblank. So try it again + * so we don't accidentally end up spanning a vblank frame + * increment, causing the pipe_update_end() code to squak at us. + * + * The nature of this problem means we can't simply check the ISR + * bit and return the vblank start value; nor can we use the scanline + * debug register in the transcoder as it appears to have the same + * problem. We may need to extend this to include other platforms, + * but so far testing only shows the problem on HSW. + */ + if (HAS_DDI(display) && !position) { + int i, temp; + + for (i = 0; i < 100; i++) { + udelay(1); + temp = intel_de_read_fw(display, + PIPEDSL(display, pipe)) & PIPEDSL_LINE_MASK; + if (temp != position) { + position = temp; + break; + } + } + } + + /* + * See update_scanline_offset() for the details on the + * scanline_offset adjustment. + */ + return (position + vtotal + crtc->scanline_offset) % vtotal; +} + +/* + * The uncore version of the spin lock functions is used to decide + * whether we need to lock the uncore lock or not. This is only + * needed in i915, not in Xe. + * + * This lock in i915 is needed because some old platforms (at least + * IVB and possibly HSW as well), which are not supported in Xe, need + * all register accesses to the same cacheline to be serialized, + * otherwise they may hang. + */ +#ifdef I915 +static void intel_vblank_section_enter(struct intel_display *display) + __acquires(i915->uncore.lock) +{ + struct drm_i915_private *i915 = to_i915(display->drm); + spin_lock(&i915->uncore.lock); +} + +static void intel_vblank_section_exit(struct intel_display *display) + __releases(i915->uncore.lock) +{ + struct drm_i915_private *i915 = to_i915(display->drm); + spin_unlock(&i915->uncore.lock); +} +#else +static void intel_vblank_section_enter(struct intel_display *display) +{ +} + +static void intel_vblank_section_exit(struct intel_display *display) +{ +} +#endif + +static bool i915_get_crtc_scanoutpos(struct drm_crtc *_crtc, + bool in_vblank_irq, + int *vpos, int *hpos, + ktime_t *stime, ktime_t *etime, + const struct drm_display_mode *mode) +{ + struct intel_display *display = to_intel_display(_crtc->dev); + struct intel_crtc *crtc = to_intel_crtc(_crtc); + enum pipe pipe = crtc->pipe; + int position; + int vbl_start, vbl_end, hsync_start, htotal, vtotal; + unsigned long irqflags; + bool use_scanline_counter = DISPLAY_VER(display) >= 5 || + display->platform.g4x || DISPLAY_VER(display) == 2 || + crtc->mode_flags & I915_MODE_FLAG_USE_SCANLINE_COUNTER; + + if (drm_WARN_ON(display->drm, !mode->crtc_clock)) { + drm_dbg(display->drm, + "trying to get scanoutpos for disabled pipe %c\n", + pipe_name(pipe)); + return false; + } + + htotal = mode->crtc_htotal; + hsync_start = mode->crtc_hsync_start; + vtotal = intel_mode_vtotal(mode); + vbl_start = intel_mode_vblank_start(mode); + vbl_end = intel_mode_vblank_end(mode); + + /* + * Enter vblank critical section, as we will do multiple + * timing critical raw register reads, potentially with + * preemption disabled, so the following code must not block. + */ + local_irq_save(irqflags); + intel_vblank_section_enter(display); + + /* preempt_disable_rt() should go right here in PREEMPT_RT patchset. */ + + /* Get optional system timestamp before query. */ + if (stime) + *stime = ktime_get(); + + if (crtc->mode_flags & I915_MODE_FLAG_VRR) { + int scanlines = intel_crtc_scanlines_since_frame_timestamp(crtc); + + position = __intel_get_crtc_scanline(crtc); + + /* + * Already exiting vblank? If so, shift our position + * so it looks like we're already approaching the full + * vblank end. This should make the generated timestamp + * more or less match when the active portion will start. + */ + if (position >= vbl_start && scanlines < position) + position = min(crtc->vmax_vblank_start + scanlines, vtotal - 1); + } else if (use_scanline_counter) { + /* No obvious pixelcount register. Only query vertical + * scanout position from Display scan line register. + */ + position = __intel_get_crtc_scanline(crtc); + } else { + /* + * Have access to pixelcount since start of frame. + * We can split this into vertical and horizontal + * scanout position. + */ + position = (intel_de_read_fw(display, PIPEFRAMEPIXEL(display, pipe)) & PIPE_PIXEL_MASK) >> PIPE_PIXEL_SHIFT; + + /* convert to pixel counts */ + vbl_start *= htotal; + vbl_end *= htotal; + vtotal *= htotal; + + /* + * In interlaced modes, the pixel counter counts all pixels, + * so one field will have htotal more pixels. In order to avoid + * the reported position from jumping backwards when the pixel + * counter is beyond the length of the shorter field, just + * clamp the position the length of the shorter field. This + * matches how the scanline counter based position works since + * the scanline counter doesn't count the two half lines. + */ + position = min(position, vtotal - 1); + + /* + * Start of vblank interrupt is triggered at start of hsync, + * just prior to the first active line of vblank. However we + * consider lines to start at the leading edge of horizontal + * active. So, should we get here before we've crossed into + * the horizontal active of the first line in vblank, we would + * not set the DRM_SCANOUTPOS_INVBL flag. In order to fix that, + * always add htotal-hsync_start to the current pixel position. + */ + position = (position + htotal - hsync_start) % vtotal; + } + + /* Get optional system timestamp after query. */ + if (etime) + *etime = ktime_get(); + + /* preempt_enable_rt() should go right here in PREEMPT_RT patchset. */ + + intel_vblank_section_exit(display); + local_irq_restore(irqflags); + + /* + * While in vblank, position will be negative + * counting up towards 0 at vbl_end. And outside + * vblank, position will be positive counting + * up since vbl_end. + */ + if (position >= vbl_start) + position -= vbl_end; + else + position += vtotal - vbl_end; + + if (use_scanline_counter) { + *vpos = position; + *hpos = 0; + } else { + *vpos = position / htotal; + *hpos = position - (*vpos * htotal); + } + + return true; +} + +bool intel_crtc_get_vblank_timestamp(struct drm_crtc *crtc, int *max_error, + ktime_t *vblank_time, bool in_vblank_irq) +{ + return drm_crtc_vblank_helper_get_vblank_timestamp_internal( + crtc, max_error, vblank_time, in_vblank_irq, + i915_get_crtc_scanoutpos); +} + +int intel_get_crtc_scanline(struct intel_crtc *crtc) +{ + struct intel_display *display = to_intel_display(crtc); + unsigned long irqflags; + int position; + + local_irq_save(irqflags); + intel_vblank_section_enter(display); + + position = __intel_get_crtc_scanline(crtc); + + intel_vblank_section_exit(display); + local_irq_restore(irqflags); + + return position; +} + +static bool pipe_scanline_is_moving(struct intel_display *display, + enum pipe pipe) +{ + i915_reg_t reg = PIPEDSL(display, pipe); + u32 line1, line2; + + line1 = intel_de_read(display, reg) & PIPEDSL_LINE_MASK; + msleep(5); + line2 = intel_de_read(display, reg) & PIPEDSL_LINE_MASK; + + return line1 != line2; +} + +static void wait_for_pipe_scanline_moving(struct intel_crtc *crtc, bool state) +{ + struct intel_display *display = to_intel_display(crtc); + enum pipe pipe = crtc->pipe; + bool is_moving; + int ret; + + /* Wait for the display line to settle/start moving */ + ret = poll_timeout_us(is_moving = pipe_scanline_is_moving(display, pipe), + is_moving == state, + 500, 100 * 1000, false); + if (ret) + drm_err(display->drm, + "pipe %c scanline %s wait timed out\n", + pipe_name(pipe), str_on_off(state)); +} + +void intel_wait_for_pipe_scanline_stopped(struct intel_crtc *crtc) +{ + wait_for_pipe_scanline_moving(crtc, false); +} + +void intel_wait_for_pipe_scanline_moving(struct intel_crtc *crtc) +{ + wait_for_pipe_scanline_moving(crtc, true); +} + +static void intel_crtc_active_timings(struct drm_display_mode *mode, + int *vmax_vblank_start, + const struct intel_crtc_state *crtc_state, + bool vrr_enable) +{ + drm_mode_init(mode, &crtc_state->hw.adjusted_mode); + *vmax_vblank_start = 0; + + if (!vrr_enable) + return; + + mode->crtc_vtotal = intel_vrr_vmax_vtotal(crtc_state); + mode->crtc_vblank_end = intel_vrr_vmax_vtotal(crtc_state); + mode->crtc_vblank_start = intel_vrr_vmin_vblank_start(crtc_state); + *vmax_vblank_start = intel_vrr_vmax_vblank_start(crtc_state); +} + +void intel_crtc_update_active_timings(const struct intel_crtc_state *crtc_state, + bool vrr_enable) +{ + struct intel_display *display = to_intel_display(crtc_state); + struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc); + u8 mode_flags = crtc_state->mode_flags; + struct drm_display_mode adjusted_mode; + int vmax_vblank_start = 0; + unsigned long irqflags; + + intel_crtc_active_timings(&adjusted_mode, &vmax_vblank_start, + crtc_state, vrr_enable); + + if (vrr_enable) + drm_WARN_ON(display->drm, (mode_flags & I915_MODE_FLAG_VRR) == 0); + else + mode_flags &= ~I915_MODE_FLAG_VRR; + + /* + * Belts and suspenders locking to guarantee everyone sees 100% + * consistent state during fastset seamless refresh rate changes. + * + * vblank_time_lock takes care of all drm_vblank.c stuff, and + * uncore.lock takes care of __intel_get_crtc_scanline() which + * may get called elsewhere as well. + * + * TODO maybe just protect everything (including + * __intel_get_crtc_scanline()) with vblank_time_lock? + * Need to audit everything to make sure it's safe. + */ + spin_lock_irqsave(&display->drm->vblank_time_lock, irqflags); + intel_vblank_section_enter(display); + + drm_calc_timestamping_constants(&crtc->base, &adjusted_mode); + + crtc->vmax_vblank_start = vmax_vblank_start; + + crtc->mode_flags = mode_flags; + + crtc->scanline_offset = intel_crtc_scanline_offset(crtc_state); + intel_vblank_section_exit(display); + spin_unlock_irqrestore(&display->drm->vblank_time_lock, irqflags); +} + +int intel_mode_vdisplay(const struct drm_display_mode *mode) +{ + int vdisplay = mode->crtc_vdisplay; + + if (mode->flags & DRM_MODE_FLAG_INTERLACE) + vdisplay = DIV_ROUND_UP(vdisplay, 2); + + return vdisplay; +} + +int intel_mode_vblank_start(const struct drm_display_mode *mode) +{ + int vblank_start = mode->crtc_vblank_start; + + if (mode->flags & DRM_MODE_FLAG_INTERLACE) + vblank_start = DIV_ROUND_UP(vblank_start, 2); + + return vblank_start; +} + +int intel_mode_vblank_end(const struct drm_display_mode *mode) +{ + int vblank_end = mode->crtc_vblank_end; + + if (mode->flags & DRM_MODE_FLAG_INTERLACE) + vblank_end /= 2; + + return vblank_end; +} + +int intel_mode_vtotal(const struct drm_display_mode *mode) +{ + int vtotal = mode->crtc_vtotal; + + if (mode->flags & DRM_MODE_FLAG_INTERLACE) + vtotal /= 2; + + return vtotal; +} + +int intel_mode_vblank_delay(const struct drm_display_mode *mode) +{ + return intel_mode_vblank_start(mode) - intel_mode_vdisplay(mode); +} + +static const struct intel_crtc_state * +pre_commit_crtc_state(const struct intel_crtc_state *old_crtc_state, + const struct intel_crtc_state *new_crtc_state) +{ + /* + * During fastsets/etc. the transcoder is still + * running with the old timings at this point. + */ + if (intel_crtc_needs_modeset(new_crtc_state)) + return new_crtc_state; + else + return old_crtc_state; +} + +const struct intel_crtc_state * +intel_pre_commit_crtc_state(struct intel_atomic_state *state, + struct intel_crtc *crtc) +{ + const struct intel_crtc_state *old_crtc_state = + intel_atomic_get_old_crtc_state(state, crtc); + const struct intel_crtc_state *new_crtc_state = + intel_atomic_get_new_crtc_state(state, crtc); + + return pre_commit_crtc_state(old_crtc_state, new_crtc_state); +} + +void intel_vblank_evade_init(const struct intel_crtc_state *old_crtc_state, + const struct intel_crtc_state *new_crtc_state, + struct intel_vblank_evade_ctx *evade) +{ + struct intel_display *display = to_intel_display(new_crtc_state); + struct intel_crtc *crtc = to_intel_crtc(new_crtc_state->uapi.crtc); + const struct intel_crtc_state *crtc_state; + const struct drm_display_mode *adjusted_mode; + int vblank_delay; + + evade->crtc = crtc; + + evade->need_vlv_dsi_wa = (display->platform.valleyview || + display->platform.cherryview) && + intel_crtc_has_type(new_crtc_state, INTEL_OUTPUT_DSI); + + /* TODO: maybe just use the active timings here? */ + crtc_state = pre_commit_crtc_state(old_crtc_state, new_crtc_state); + + adjusted_mode = &crtc_state->hw.adjusted_mode; + + if (crtc->mode_flags & I915_MODE_FLAG_VRR) { + /* timing changes should happen with VRR disabled */ + drm_WARN_ON(crtc->base.dev, intel_crtc_needs_modeset(new_crtc_state) || + new_crtc_state->update_m_n || new_crtc_state->update_lrr); + + if (intel_vrr_is_push_sent(crtc_state)) + evade->vblank_start = intel_vrr_vmin_vblank_start(crtc_state); + else + evade->vblank_start = intel_vrr_vmax_vblank_start(crtc_state); + + vblank_delay = crtc_state->set_context_latency; + } else { + evade->vblank_start = intel_mode_vblank_start(adjusted_mode); + + vblank_delay = intel_mode_vblank_delay(adjusted_mode); + } + + /* FIXME needs to be calibrated sensibly */ + evade->min = evade->vblank_start - intel_usecs_to_scanlines(adjusted_mode, + VBLANK_EVASION_TIME_US); + evade->max = evade->vblank_start - 1; + + /* + * M/N and TRANS_VTOTAL are double buffered on the transcoder's + * undelayed vblank, so with seamless M/N and LRR we must evade + * both vblanks. + * + * DSB execution waits for the transcoder's undelayed vblank, + * hence we must kick off the commit before that. + */ + if (intel_color_uses_dsb(new_crtc_state) || + new_crtc_state->update_m_n || new_crtc_state->update_lrr) + evade->min -= vblank_delay; +} + +/* must be called with vblank interrupt already enabled! */ +int intel_vblank_evade(struct intel_vblank_evade_ctx *evade) +{ + struct intel_crtc *crtc = evade->crtc; + struct intel_display *display = to_intel_display(crtc); + long timeout = msecs_to_jiffies_timeout(1); + wait_queue_head_t *wq = drm_crtc_vblank_waitqueue(&crtc->base); + DEFINE_WAIT(wait); + int scanline; + + if (evade->min <= 0 || evade->max <= 0) + return 0; + + for (;;) { + /* + * prepare_to_wait() has a memory barrier, which guarantees + * other CPUs can see the task state update by the time we + * read the scanline. + */ + prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE); + + scanline = intel_get_crtc_scanline(crtc); + if (scanline < evade->min || scanline > evade->max) + break; + + if (!timeout) { + drm_dbg_kms(display->drm, + "Potential atomic update failure on pipe %c\n", + pipe_name(crtc->pipe)); + break; + } + + local_irq_enable(); + + timeout = schedule_timeout(timeout); + + local_irq_disable(); + } + + finish_wait(wq, &wait); + + /* + * On VLV/CHV DSI the scanline counter would appear to + * increment approx. 1/3 of a scanline before start of vblank. + * The registers still get latched at start of vblank however. + * This means we must not write any registers on the first + * line of vblank (since not the whole line is actually in + * vblank). And unfortunately we can't use the interrupt to + * wait here since it will fire too soon. We could use the + * frame start interrupt instead since it will fire after the + * critical scanline, but that would require more changes + * in the interrupt code. So for now we'll just do the nasty + * thing and poll for the bad scanline to pass us by. + * + * FIXME figure out if BXT+ DSI suffers from this as well + */ + while (evade->need_vlv_dsi_wa && scanline == evade->vblank_start) + scanline = intel_get_crtc_scanline(crtc); + + return scanline; +} + +int intel_crtc_vblank_length(const struct intel_crtc_state *crtc_state) +{ + const struct drm_display_mode *adjusted_mode = &crtc_state->hw.adjusted_mode; + + if (crtc_state->vrr.enable) + return crtc_state->vrr.guardband; + else + return adjusted_mode->crtc_vtotal - adjusted_mode->crtc_vblank_start; +} |