diff options
Diffstat (limited to 'drivers/gpu/drm/i915/display/intel_vblank.c')
| -rw-r--r-- | drivers/gpu/drm/i915/display/intel_vblank.c | 401 |
1 files changed, 269 insertions, 132 deletions
diff --git a/drivers/gpu/drm/i915/display/intel_vblank.c b/drivers/gpu/drm/i915/display/intel_vblank.c index fe256bf7b485..a95fb3349eba 100644 --- a/drivers/gpu/drm/i915/display/intel_vblank.c +++ b/drivers/gpu/drm/i915/display/intel_vblank.c @@ -3,8 +3,12 @@ * Copyright © 2022-2023 Intel Corporation */ +#include <drm/drm_vblank.h> + #include "i915_drv.h" #include "i915_reg.h" +#include "intel_color.h" +#include "intel_crtc.h" #include "intel_de.h" #include "intel_display_types.h" #include "intel_vblank.h" @@ -65,8 +69,8 @@ */ u32 i915_get_vblank_counter(struct drm_crtc *crtc) { - struct drm_i915_private *dev_priv = to_i915(crtc->dev); - struct drm_vblank_crtc *vblank = &dev_priv->drm.vblank[drm_crtc_index(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; @@ -88,9 +92,7 @@ u32 i915_get_vblank_counter(struct drm_crtc *crtc) htotal = mode->crtc_htotal; hsync_start = mode->crtc_hsync_start; - vbl_start = mode->crtc_vblank_start; - if (mode->flags & DRM_MODE_FLAG_INTERLACE) - vbl_start = DIV_ROUND_UP(vbl_start, 2); + vbl_start = intel_mode_vblank_start(mode); /* Convert to pixel count */ vbl_start *= htotal; @@ -103,7 +105,8 @@ u32 i915_get_vblank_counter(struct drm_crtc *crtc) * we get a low value that's stable across two reads of the high * register. */ - frame = intel_de_read64_2x32(dev_priv, PIPEFRAMEPIXEL(pipe), PIPEFRAME(pipe)); + frame = intel_de_read64_2x32(display, PIPEFRAMEPIXEL(display, pipe), + PIPEFRAME(display, pipe)); pixel = frame & PIPE_PIXEL_MASK; frame = (frame >> PIPE_FRAME_LOW_SHIFT) & 0xffffff; @@ -118,21 +121,20 @@ u32 i915_get_vblank_counter(struct drm_crtc *crtc) u32 g4x_get_vblank_counter(struct drm_crtc *crtc) { - struct drm_i915_private *dev_priv = to_i915(crtc->dev); - struct drm_vblank_crtc *vblank = &dev_priv->drm.vblank[drm_crtc_index(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(dev_priv, PIPE_FRMCOUNT_G4X(pipe)); + return intel_de_read(display, PIPE_FRMCOUNT_G4X(display, pipe)); } static u32 intel_crtc_scanlines_since_frame_timestamp(struct intel_crtc *crtc) { - struct drm_i915_private *dev_priv = to_i915(crtc->base.dev); - struct drm_vblank_crtc *vblank = - &crtc->base.dev->vblank[drm_crtc_index(&crtc->base)]; + 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; @@ -150,16 +152,16 @@ static u32 intel_crtc_scanlines_since_frame_timestamp(struct intel_crtc *crtc) * pipe frame time stamp. The time stamp value * is sampled at every start of vertical blank. */ - scan_prev_time = intel_de_read_fw(dev_priv, + 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(dev_priv, IVB_TIMESTAMP_CTR); + scan_curr_time = intel_de_read_fw(display, IVB_TIMESTAMP_CTR); - scan_post_time = intel_de_read_fw(dev_priv, + scan_post_time = intel_de_read_fw(display, PIPE_FRMTMSTMP(crtc->pipe)); } while (scan_post_time != scan_prev_time); @@ -177,8 +179,7 @@ static u32 intel_crtc_scanlines_since_frame_timestamp(struct intel_crtc *crtc) */ static u32 __intel_get_crtc_scanline_from_timestamp(struct intel_crtc *crtc) { - struct drm_vblank_crtc *vblank = - &crtc->base.dev->vblank[drm_crtc_index(&crtc->base)]; + 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; @@ -191,33 +192,65 @@ static u32 __intel_get_crtc_scanline_from_timestamp(struct intel_crtc *crtc) 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) == 2) + return -1; + else if (HAS_DDI(display) && intel_crtc_has_type(crtc_state, INTEL_OUTPUT_HDMI)) + return 2; + 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 drm_device *dev = crtc->base.dev; - struct drm_i915_private *dev_priv = to_i915(dev); - const struct drm_display_mode *mode; - struct drm_vblank_crtc *vblank; + 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; - vblank = &crtc->base.dev->vblank[drm_crtc_index(&crtc->base)]; - mode = &vblank->hwmode; - if (crtc->mode_flags & I915_MODE_FLAG_GET_SCANLINE_FROM_TIMESTAMP) return __intel_get_crtc_scanline_from_timestamp(crtc); - vtotal = mode->crtc_vtotal; - if (mode->flags & DRM_MODE_FLAG_INTERLACE) - vtotal /= 2; + vtotal = intel_mode_vtotal(mode); - position = intel_de_read_fw(dev_priv, PIPEDSL(pipe)) & PIPEDSL_LINE_MASK; + position = intel_de_read_fw(display, PIPEDSL(display, pipe)) & PIPEDSL_LINE_MASK; /* * On HSW, the DSL reg (0x70000) appears to return 0 if we @@ -231,12 +264,13 @@ static int __intel_get_crtc_scanline(struct intel_crtc *crtc) * problem. We may need to extend this to include other platforms, * but so far testing only shows the problem on HSW. */ - if (HAS_DDI(dev_priv) && !position) { + if (HAS_DDI(display) && !position) { int i, temp; for (i = 0; i < 100; i++) { udelay(1); - temp = intel_de_read_fw(dev_priv, PIPEDSL(pipe)) & PIPEDSL_LINE_MASK; + temp = intel_de_read_fw(display, + PIPEDSL(display, pipe)) & PIPEDSL_LINE_MASK; if (temp != position) { position = temp; break; @@ -248,21 +282,7 @@ static int __intel_get_crtc_scanline(struct intel_crtc *crtc) * See update_scanline_offset() for the details on the * scanline_offset adjustment. */ - return (position + crtc->scanline_offset) % vtotal; -} - -int intel_crtc_scanline_to_hw(struct intel_crtc *crtc, int scanline) -{ - const struct drm_vblank_crtc *vblank = - &crtc->base.dev->vblank[drm_crtc_index(&crtc->base)]; - const struct drm_display_mode *mode = &vblank->hwmode; - int vtotal; - - vtotal = mode->crtc_vtotal; - if (mode->flags & DRM_MODE_FLAG_INTERLACE) - vtotal /= 2; - - return (scanline + vtotal - crtc->scanline_offset) % vtotal; + return (position + vtotal + crtc->scanline_offset) % vtotal; } /* @@ -275,21 +295,29 @@ int intel_crtc_scanline_to_hw(struct intel_crtc *crtc, int scanline) * all register accesses to the same cacheline to be serialized, * otherwise they may hang. */ -static void intel_vblank_section_enter(struct drm_i915_private *i915) +#ifdef I915 +static void intel_vblank_section_enter(struct intel_display *display) __acquires(i915->uncore.lock) { -#ifdef I915 + struct drm_i915_private *i915 = to_i915(display->drm); spin_lock(&i915->uncore.lock); -#endif } -static void intel_vblank_section_exit(struct drm_i915_private *i915) +static void intel_vblank_section_exit(struct intel_display *display) __releases(i915->uncore.lock) { -#ifdef I915 + struct drm_i915_private *i915 = to_i915(display->drm); spin_unlock(&i915->uncore.lock); -#endif } +#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, @@ -297,19 +325,18 @@ static bool i915_get_crtc_scanoutpos(struct drm_crtc *_crtc, ktime_t *stime, ktime_t *etime, const struct drm_display_mode *mode) { - struct drm_device *dev = _crtc->dev; - struct drm_i915_private *dev_priv = to_i915(dev); + 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(dev_priv) >= 5 || - IS_G4X(dev_priv) || DISPLAY_VER(dev_priv) == 2 || + 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(&dev_priv->drm, !mode->crtc_clock)) { - drm_dbg(&dev_priv->drm, + 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; @@ -317,15 +344,9 @@ static bool i915_get_crtc_scanoutpos(struct drm_crtc *_crtc, htotal = mode->crtc_htotal; hsync_start = mode->crtc_hsync_start; - vtotal = mode->crtc_vtotal; - vbl_start = mode->crtc_vblank_start; - vbl_end = mode->crtc_vblank_end; - - if (mode->flags & DRM_MODE_FLAG_INTERLACE) { - vbl_start = DIV_ROUND_UP(vbl_start, 2); - vbl_end /= 2; - vtotal /= 2; - } + 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 @@ -333,7 +354,7 @@ static bool i915_get_crtc_scanoutpos(struct drm_crtc *_crtc, * preemption disabled, so the following code must not block. */ local_irq_save(irqflags); - intel_vblank_section_enter(dev_priv); + intel_vblank_section_enter(display); /* preempt_disable_rt() should go right here in PREEMPT_RT patchset. */ @@ -365,7 +386,7 @@ static bool i915_get_crtc_scanoutpos(struct drm_crtc *_crtc, * We can split this into vertical and horizontal * scanout position. */ - position = (intel_de_read_fw(dev_priv, PIPEFRAMEPIXEL(pipe)) & PIPE_PIXEL_MASK) >> PIPE_PIXEL_SHIFT; + position = (intel_de_read_fw(display, PIPEFRAMEPIXEL(display, pipe)) & PIPE_PIXEL_MASK) >> PIPE_PIXEL_SHIFT; /* convert to pixel counts */ vbl_start *= htotal; @@ -401,7 +422,7 @@ static bool i915_get_crtc_scanoutpos(struct drm_crtc *_crtc, /* preempt_enable_rt() should go right here in PREEMPT_RT patchset. */ - intel_vblank_section_exit(dev_priv); + intel_vblank_section_exit(display); local_irq_restore(irqflags); /* @@ -436,42 +457,42 @@ bool intel_crtc_get_vblank_timestamp(struct drm_crtc *crtc, int *max_error, int intel_get_crtc_scanline(struct intel_crtc *crtc) { - struct drm_i915_private *dev_priv = to_i915(crtc->base.dev); + struct intel_display *display = to_intel_display(crtc); unsigned long irqflags; int position; local_irq_save(irqflags); - intel_vblank_section_enter(dev_priv); + intel_vblank_section_enter(display); position = __intel_get_crtc_scanline(crtc); - intel_vblank_section_exit(dev_priv); + intel_vblank_section_exit(display); local_irq_restore(irqflags); return position; } -static bool pipe_scanline_is_moving(struct drm_i915_private *dev_priv, +static bool pipe_scanline_is_moving(struct intel_display *display, enum pipe pipe) { - i915_reg_t reg = PIPEDSL(pipe); + i915_reg_t reg = PIPEDSL(display, pipe); u32 line1, line2; - line1 = intel_de_read(dev_priv, reg) & PIPEDSL_LINE_MASK; + line1 = intel_de_read(display, reg) & PIPEDSL_LINE_MASK; msleep(5); - line2 = intel_de_read(dev_priv, reg) & PIPEDSL_LINE_MASK; + 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 drm_i915_private *dev_priv = to_i915(crtc->base.dev); + struct intel_display *display = to_intel_display(crtc); enum pipe pipe = crtc->pipe; /* Wait for the display line to settle/start moving */ - if (wait_for(pipe_scanline_is_moving(dev_priv, pipe) == state, 100)) - drm_err(&dev_priv->drm, + if (wait_for(pipe_scanline_is_moving(display, pipe) == state, 100)) + drm_err(display->drm, "pipe %c scanline %s wait timed out\n", pipe_name(pipe), str_on_off(state)); } @@ -486,58 +507,11 @@ void intel_wait_for_pipe_scanline_moving(struct intel_crtc *crtc) wait_for_pipe_scanline_moving(crtc, true); } -static int intel_crtc_scanline_offset(const struct intel_crtc_state *crtc_state) -{ - struct drm_i915_private *i915 = to_i915(crtc_state->uapi.crtc->dev); - const struct drm_display_mode *adjusted_mode = &crtc_state->hw.adjusted_mode; - - /* - * 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 (or rather add vtotal-1 - * to keep the value positive), instead of adding 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(i915) == 2) { - int vtotal; - - vtotal = adjusted_mode->crtc_vtotal; - if (adjusted_mode->flags & DRM_MODE_FLAG_INTERLACE) - vtotal /= 2; - - return vtotal - 1; - } else if (HAS_DDI(i915) && intel_crtc_has_type(crtc_state, INTEL_OUTPUT_HDMI)) { - return 2; - } else { - return 1; - } -} - 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); - struct drm_i915_private *i915 = to_i915(crtc->base.dev); u8 mode_flags = crtc_state->mode_flags; struct drm_display_mode adjusted_mode; int vmax_vblank_start = 0; @@ -546,7 +520,8 @@ void intel_crtc_update_active_timings(const struct intel_crtc_state *crtc_state, drm_mode_init(&adjusted_mode, &crtc_state->hw.adjusted_mode); if (vrr_enable) { - drm_WARN_ON(&i915->drm, (mode_flags & I915_MODE_FLAG_VRR) == 0); + drm_WARN_ON(display->drm, + (mode_flags & I915_MODE_FLAG_VRR) == 0); adjusted_mode.crtc_vtotal = crtc_state->vrr.vmax; adjusted_mode.crtc_vblank_end = crtc_state->vrr.vmax; @@ -568,8 +543,8 @@ void intel_crtc_update_active_timings(const struct intel_crtc_state *crtc_state, * __intel_get_crtc_scanline()) with vblank_time_lock? * Need to audit everything to make sure it's safe. */ - spin_lock_irqsave(&i915->drm.vblank_time_lock, irqflags); - intel_vblank_section_enter(i915); + spin_lock_irqsave(&display->drm->vblank_time_lock, irqflags); + intel_vblank_section_enter(display); drm_calc_timestamping_constants(&crtc->base, &adjusted_mode); @@ -578,6 +553,168 @@ void intel_crtc_update_active_timings(const struct intel_crtc_state *crtc_state, crtc->mode_flags = mode_flags; crtc->scanline_offset = intel_crtc_scanline_offset(crtc_state); - intel_vblank_section_exit(i915); - spin_unlock_irqrestore(&i915->drm.vblank_time_lock, irqflags); + 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; +} + +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; + + evade->crtc = crtc; + + evade->need_vlv_dsi_wa = (display->platform.valleyview || + display->platform.cherryview) && + intel_crtc_has_type(new_crtc_state, INTEL_OUTPUT_DSI); + + /* + * During fastsets/etc. the transcoder is still + * running with the old timings at this point. + * + * TODO: maybe just use the active timings here? + */ + if (intel_crtc_needs_modeset(new_crtc_state)) + crtc_state = new_crtc_state; + else + crtc_state = old_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); + } else { + evade->vblank_start = intel_mode_vblank_start(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 -= intel_mode_vblank_start(adjusted_mode) - + intel_mode_vdisplay(adjusted_mode); +} + +/* 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_err(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; } |