diff options
Diffstat (limited to 'drivers/gpu/drm/drm_vblank.c')
| -rw-r--r-- | drivers/gpu/drm/drm_vblank.c | 180 |
1 files changed, 173 insertions, 7 deletions
diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c index 46f59883183d..5c14140cd0c2 100644 --- a/drivers/gpu/drm/drm_vblank.c +++ b/drivers/gpu/drm/drm_vblank.c @@ -136,8 +136,17 @@ * vblanks after a timer has expired, which can be configured through the * ``vblankoffdelay`` module parameter. * - * Drivers for hardware without support for vertical-blanking interrupts - * must not call drm_vblank_init(). For such drivers, atomic helpers will + * Drivers for hardware without support for vertical-blanking interrupts can + * use DRM vblank timers to send vblank events at the rate of the current + * display mode's refresh. While not synchronized to the hardware's + * vertical-blanking regions, the timer helps DRM clients and compositors to + * adapt their update cycle to the display output. Drivers should set up + * vblanking as usual, but call drm_crtc_vblank_start_timer() and + * drm_crtc_vblank_cancel_timer() as part of their atomic mode setting. + * See also DRM vblank helpers for more information. + * + * Drivers without support for vertical-blanking interrupts nor timers must + * not call drm_vblank_init(). For these drivers, atomic helpers will * automatically generate fake vblank events as part of the display update. * This functionality also can be controlled by the driver by enabling and * disabling struct drm_crtc_state.no_vblank. @@ -508,6 +517,9 @@ static void drm_vblank_init_release(struct drm_device *dev, void *ptr) drm_WARN_ON(dev, READ_ONCE(vblank->enabled) && drm_core_check_feature(dev, DRIVER_MODESET)); + if (vblank->vblank_timer.crtc) + hrtimer_cancel(&vblank->vblank_timer.timer); + drm_vblank_destroy_worker(vblank); timer_delete_sync(&vblank->disable_timer); } @@ -794,10 +806,8 @@ drm_crtc_vblank_helper_get_vblank_timestamp_internal( ts_vblank_time = ktime_to_timespec64(*vblank_time); drm_dbg_vbl(dev, - "crtc %u : v p(%d,%d)@ %lld.%06ld -> %lld.%06ld [e %d us, %d rep]\n", - pipe, hpos, vpos, - (u64)ts_etime.tv_sec, ts_etime.tv_nsec / 1000, - (u64)ts_vblank_time.tv_sec, ts_vblank_time.tv_nsec / 1000, + "crtc %u : v p(%d,%d)@ %ptSp -> %ptSp [e %d us, %d rep]\n", + pipe, hpos, vpos, &ts_etime, &ts_vblank_time, duration_ns / 1000, i); return true; @@ -1303,7 +1313,7 @@ void drm_wait_one_vblank(struct drm_device *dev, unsigned int pipe) ret = wait_event_timeout(vblank->queue, last != drm_vblank_count(dev, pipe), - msecs_to_jiffies(100)); + msecs_to_jiffies(1000)); drm_WARN(dev, ret == 0, "vblank wait timed out on crtc %i\n", pipe); @@ -2162,3 +2172,159 @@ err_free: return ret; } +/* + * VBLANK timer + */ + +static enum hrtimer_restart drm_vblank_timer_function(struct hrtimer *timer) +{ + struct drm_vblank_crtc_timer *vtimer = + container_of(timer, struct drm_vblank_crtc_timer, timer); + struct drm_crtc *crtc = vtimer->crtc; + const struct drm_crtc_helper_funcs *crtc_funcs = crtc->helper_private; + struct drm_device *dev = crtc->dev; + unsigned long flags; + ktime_t interval; + u64 ret_overrun; + bool succ; + + spin_lock_irqsave(&vtimer->interval_lock, flags); + interval = vtimer->interval; + spin_unlock_irqrestore(&vtimer->interval_lock, flags); + + if (!interval) + return HRTIMER_NORESTART; + + ret_overrun = hrtimer_forward_now(&vtimer->timer, interval); + if (ret_overrun != 1) + drm_dbg_vbl(dev, "vblank timer overrun\n"); + + if (crtc_funcs->handle_vblank_timeout) + succ = crtc_funcs->handle_vblank_timeout(crtc); + else + succ = drm_crtc_handle_vblank(crtc); + if (!succ) + return HRTIMER_NORESTART; + + return HRTIMER_RESTART; +} + +/** + * drm_crtc_vblank_start_timer - Starts the vblank timer on the given CRTC + * @crtc: the CRTC + * + * Drivers should call this function from their CRTC's enable_vblank + * function to start a vblank timer. The timer will fire after the duration + * of a full frame. drm_crtc_vblank_cancel_timer() disables a running timer. + * + * Returns: + * 0 on success, or a negative errno code otherwise. + */ +int drm_crtc_vblank_start_timer(struct drm_crtc *crtc) +{ + struct drm_vblank_crtc *vblank = drm_crtc_vblank_crtc(crtc); + struct drm_vblank_crtc_timer *vtimer = &vblank->vblank_timer; + unsigned long flags; + + if (!vtimer->crtc) { + /* + * Set up the data structures on the first invocation. + */ + vtimer->crtc = crtc; + spin_lock_init(&vtimer->interval_lock); + hrtimer_setup(&vtimer->timer, drm_vblank_timer_function, + CLOCK_MONOTONIC, HRTIMER_MODE_REL); + } else { + /* + * Timer should not be active. If it is, wait for the + * previous cancel operations to finish. + */ + while (hrtimer_active(&vtimer->timer)) + hrtimer_try_to_cancel(&vtimer->timer); + } + + drm_calc_timestamping_constants(crtc, &crtc->mode); + + spin_lock_irqsave(&vtimer->interval_lock, flags); + vtimer->interval = ns_to_ktime(vblank->framedur_ns); + spin_unlock_irqrestore(&vtimer->interval_lock, flags); + + hrtimer_start(&vtimer->timer, vtimer->interval, HRTIMER_MODE_REL); + + return 0; +} +EXPORT_SYMBOL(drm_crtc_vblank_start_timer); + +/** + * drm_crtc_vblank_cancel_timer - Cancels the given CRTC's vblank timer + * @crtc: the CRTC + * + * Drivers should call this function from their CRTC's disable_vblank + * function to stop a vblank timer. + */ +void drm_crtc_vblank_cancel_timer(struct drm_crtc *crtc) +{ + struct drm_vblank_crtc *vblank = drm_crtc_vblank_crtc(crtc); + struct drm_vblank_crtc_timer *vtimer = &vblank->vblank_timer; + unsigned long flags; + + /* + * Calling hrtimer_cancel() can result in a deadlock with DRM's + * vblank_time_lime_lock and hrtimers' softirq_expiry_lock. So + * clear interval and indicate cancellation. The timer function + * will cancel itself on the next invocation. + */ + + spin_lock_irqsave(&vtimer->interval_lock, flags); + vtimer->interval = 0; + spin_unlock_irqrestore(&vtimer->interval_lock, flags); + + hrtimer_try_to_cancel(&vtimer->timer); +} +EXPORT_SYMBOL(drm_crtc_vblank_cancel_timer); + +/** + * drm_crtc_vblank_get_vblank_timeout - Returns the vblank timeout + * @crtc: The CRTC + * @vblank_time: Returns the next vblank timestamp + * + * The helper drm_crtc_vblank_get_vblank_timeout() returns the next vblank + * timestamp of the CRTC's vblank timer according to the timer's expiry + * time. + */ +void drm_crtc_vblank_get_vblank_timeout(struct drm_crtc *crtc, ktime_t *vblank_time) +{ + struct drm_vblank_crtc *vblank = drm_crtc_vblank_crtc(crtc); + struct drm_vblank_crtc_timer *vtimer = &vblank->vblank_timer; + u64 cur_count; + ktime_t cur_time; + + if (!READ_ONCE(vblank->enabled)) { + *vblank_time = ktime_get(); + return; + } + + /* + * A concurrent vblank timeout could update the expires field before + * we compare it with the vblank time. Hence we'd compare the old + * expiry time to the new vblank time; deducing the timer had already + * expired. Reread until we get consistent values from both fields. + */ + do { + cur_count = drm_crtc_vblank_count_and_time(crtc, &cur_time); + *vblank_time = READ_ONCE(vtimer->timer.node.expires); + } while (cur_count != drm_crtc_vblank_count_and_time(crtc, &cur_time)); + + if (drm_WARN_ON(crtc->dev, !ktime_compare(*vblank_time, cur_time))) + return; /* Already expired */ + + /* + * To prevent races we roll the hrtimer forward before we do any + * interrupt processing - this is how real hw works (the interrupt + * is only generated after all the vblank registers are updated) + * and what the vblank core expects. Therefore we need to always + * correct the timestamp by one frame. + */ + *vblank_time = ktime_sub(*vblank_time, vtimer->interval); +} +EXPORT_SYMBOL(drm_crtc_vblank_get_vblank_timeout); |