diff options
Diffstat (limited to 'drivers/gpu/drm/drm_irq.c')
| -rw-r--r-- | drivers/gpu/drm/drm_irq.c | 215 |
1 files changed, 62 insertions, 153 deletions
diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c index 0fac801c18fe..8ca3d2bf2bda 100644 --- a/drivers/gpu/drm/drm_irq.c +++ b/drivers/gpu/drm/drm_irq.c @@ -42,10 +42,6 @@ #include <linux/vgaarb.h> #include <linux/export.h> -/* Access macro for slots in vblank timestamp ringbuffer. */ -#define vblanktimestamp(dev, pipe, count) \ - ((dev)->vblank[pipe].time[(count) % DRM_VBLANKTIME_RBSIZE]) - /* Retry timestamp calculation up to 3 times to satisfy * drm_timestamp_precision before giving up. */ @@ -82,36 +78,18 @@ static void store_vblank(struct drm_device *dev, unsigned int pipe, struct timeval *t_vblank, u32 last) { struct drm_vblank_crtc *vblank = &dev->vblank[pipe]; - u32 tslot; assert_spin_locked(&dev->vblank_time_lock); vblank->last = last; - /* All writers hold the spinlock, but readers are serialized by - * the latching of vblank->count below. - */ - tslot = vblank->count + vblank_count_inc; - vblanktimestamp(dev, pipe, tslot) = *t_vblank; - - /* - * vblank timestamp updates are protected on the write side with - * vblank_time_lock, but on the read side done locklessly using a - * sequence-lock on the vblank counter. Ensure correct ordering using - * memory barrriers. We need the barrier both before and also after the - * counter update to synchronize with the next timestamp write. - * The read-side barriers for this are in drm_vblank_count_and_time. - */ - smp_wmb(); + write_seqlock(&vblank->seqlock); + vblank->time = *t_vblank; vblank->count += vblank_count_inc; - smp_wmb(); + write_sequnlock(&vblank->seqlock); } -/** - * drm_reset_vblank_timestamp - reset the last timestamp to the last vblank - * @dev: DRM device - * @pipe: index of CRTC for which to reset the timestamp - * +/* * Reset the stored timestamp for the current vblank count to correspond * to the last vblank occurred. * @@ -155,11 +133,7 @@ static void drm_reset_vblank_timestamp(struct drm_device *dev, unsigned int pipe spin_unlock(&dev->vblank_time_lock); } -/** - * drm_update_vblank_count - update the master vblank counter - * @dev: DRM device - * @pipe: counter to update - * +/* * Call back into the driver to update the appropriate vblank counter * (specified by @pipe). Deal with wraparound, if it occurred, and * update the last read value so we can deal with wraparound on the next @@ -205,7 +179,7 @@ static void drm_update_vblank_count(struct drm_device *dev, unsigned int pipe, const struct timeval *t_old; u64 diff_ns; - t_old = &vblanktimestamp(dev, pipe, vblank->count); + t_old = &vblank->time; diff_ns = timeval_to_ns(&t_vblank) - timeval_to_ns(t_old); /* @@ -239,49 +213,6 @@ static void drm_update_vblank_count(struct drm_device *dev, unsigned int pipe, diff = 1; } - /* - * FIMXE: Need to replace this hack with proper seqlocks. - * - * Restrict the bump of the software vblank counter to a safe maximum - * value of +1 whenever there is the possibility that concurrent readers - * of vblank timestamps could be active at the moment, as the current - * implementation of the timestamp caching and updating is not safe - * against concurrent readers for calls to store_vblank() with a bump - * of anything but +1. A bump != 1 would very likely return corrupted - * timestamps to userspace, because the same slot in the cache could - * be concurrently written by store_vblank() and read by one of those - * readers without the read-retry logic detecting the collision. - * - * Concurrent readers can exist when we are called from the - * drm_vblank_off() or drm_vblank_on() functions and other non-vblank- - * irq callers. However, all those calls to us are happening with the - * vbl_lock locked to prevent drm_vblank_get(), so the vblank refcount - * can't increase while we are executing. Therefore a zero refcount at - * this point is safe for arbitrary counter bumps if we are called - * outside vblank irq, a non-zero count is not 100% safe. Unfortunately - * we must also accept a refcount of 1, as whenever we are called from - * drm_vblank_get() -> drm_vblank_enable() the refcount will be 1 and - * we must let that one pass through in order to not lose vblank counts - * during vblank irq off - which would completely defeat the whole - * point of this routine. - * - * Whenever we are called from vblank irq, we have to assume concurrent - * readers exist or can show up any time during our execution, even if - * the refcount is currently zero, as vblank irqs are usually only - * enabled due to the presence of readers, and because when we are called - * from vblank irq we can't hold the vbl_lock to protect us from sudden - * bumps in vblank refcount. Therefore also restrict bumps to +1 when - * called from vblank irq. - */ - if ((diff > 1) && (atomic_read(&vblank->refcount) > 1 || - (flags & DRM_CALLED_FROM_VBLIRQ))) { - DRM_DEBUG_VBL("clamping vblank bump to 1 on crtc %u: diffr=%u " - "refcount %u, vblirq %u\n", pipe, diff, - atomic_read(&vblank->refcount), - (flags & DRM_CALLED_FROM_VBLIRQ) != 0); - diff = 1; - } - DRM_DEBUG_VBL("updating vblank count on crtc %u:" " current=%u, diff=%u, hw=%u hw_last=%u\n", pipe, vblank->count, diff, cur_vblank, vblank->last); @@ -303,6 +234,37 @@ static void drm_update_vblank_count(struct drm_device *dev, unsigned int pipe, store_vblank(dev, pipe, diff, &t_vblank, cur_vblank); } +/** + * drm_accurate_vblank_count - retrieve the master vblank counter + * @crtc: which counter to retrieve + * + * This function is similar to @drm_crtc_vblank_count but this + * function interpolates to handle a race with vblank irq's. + * + * This is mostly useful for hardware that can obtain the scanout + * position, but doesn't have a frame counter. + */ +u32 drm_accurate_vblank_count(struct drm_crtc *crtc) +{ + struct drm_device *dev = crtc->dev; + unsigned int pipe = drm_crtc_index(crtc); + u32 vblank; + unsigned long flags; + + WARN(!dev->driver->get_vblank_timestamp, + "This function requires support for accurate vblank timestamps."); + + spin_lock_irqsave(&dev->vblank_time_lock, flags); + + drm_update_vblank_count(dev, pipe, 0); + vblank = drm_vblank_count(dev, pipe); + + spin_unlock_irqrestore(&dev->vblank_time_lock, flags); + + return vblank; +} +EXPORT_SYMBOL(drm_accurate_vblank_count); + /* * Disable vblank irq's on crtc, make sure that last vblank count * of hardware and corresponding consistent software vblank counter @@ -417,6 +379,7 @@ int drm_vblank_init(struct drm_device *dev, unsigned int num_crtcs) init_waitqueue_head(&vblank->queue); setup_timer(&vblank->disable_timer, vblank_disable_fn, (unsigned long)vblank); + seqlock_init(&vblank->seqlock); } DRM_INFO("Supports vblank timestamp caching Rev 2 (21.10.2013).\n"); @@ -986,25 +949,19 @@ u32 drm_vblank_count_and_time(struct drm_device *dev, unsigned int pipe, struct timeval *vblanktime) { struct drm_vblank_crtc *vblank = &dev->vblank[pipe]; - int count = DRM_TIMESTAMP_MAXRETRIES; - u32 cur_vblank; + u32 vblank_count; + unsigned int seq; if (WARN_ON(pipe >= dev->num_crtcs)) return 0; - /* - * Vblank timestamps are read lockless. To ensure consistency the vblank - * counter is rechecked and ordering is ensured using memory barriers. - * This works like a seqlock. The write-side barriers are in store_vblank. - */ do { - cur_vblank = vblank->count; - smp_rmb(); - *vblanktime = vblanktimestamp(dev, pipe, cur_vblank); - smp_rmb(); - } while (cur_vblank != vblank->count && --count > 0); + seq = read_seqbegin(&vblank->seqlock); + vblank_count = vblank->count; + *vblanktime = vblank->time; + } while (read_seqretry(&vblank->seqlock, seq)); - return cur_vblank; + return vblank_count; } EXPORT_SYMBOL(drm_vblank_count_and_time); @@ -1037,39 +994,11 @@ static void send_vblank_event(struct drm_device *dev, e->event.tv_sec = now->tv_sec; e->event.tv_usec = now->tv_usec; - drm_send_event_locked(dev, &e->base); - trace_drm_vblank_event_delivered(e->base.pid, e->pipe, e->event.sequence); -} -/** - * drm_arm_vblank_event - arm vblank event after pageflip - * @dev: DRM device - * @pipe: CRTC index - * @e: the event to prepare to send - * - * A lot of drivers need to generate vblank events for the very next vblank - * interrupt. For example when the page flip interrupt happens when the page - * flip gets armed, but not when it actually executes within the next vblank - * period. This helper function implements exactly the required vblank arming - * behaviour. - * - * Caller must hold event lock. Caller must also hold a vblank reference for - * the event @e, which will be dropped when the next vblank arrives. - * - * This is the legacy version of drm_crtc_arm_vblank_event(). - */ -void drm_arm_vblank_event(struct drm_device *dev, unsigned int pipe, - struct drm_pending_vblank_event *e) -{ - assert_spin_locked(&dev->event_lock); - - e->pipe = pipe; - e->event.sequence = drm_vblank_count(dev, pipe); - list_add_tail(&e->base.link, &dev->vblank_event_list); + drm_send_event_locked(dev, &e->base); } -EXPORT_SYMBOL(drm_arm_vblank_event); /** * drm_crtc_arm_vblank_event - arm vblank event after pageflip @@ -1084,32 +1013,35 @@ EXPORT_SYMBOL(drm_arm_vblank_event); * * Caller must hold event lock. Caller must also hold a vblank reference for * the event @e, which will be dropped when the next vblank arrives. - * - * This is the native KMS version of drm_arm_vblank_event(). */ void drm_crtc_arm_vblank_event(struct drm_crtc *crtc, struct drm_pending_vblank_event *e) { - drm_arm_vblank_event(crtc->dev, drm_crtc_index(crtc), e); + struct drm_device *dev = crtc->dev; + unsigned int pipe = drm_crtc_index(crtc); + + assert_spin_locked(&dev->event_lock); + + e->pipe = pipe; + e->event.sequence = drm_vblank_count(dev, pipe); + list_add_tail(&e->base.link, &dev->vblank_event_list); } EXPORT_SYMBOL(drm_crtc_arm_vblank_event); /** - * drm_send_vblank_event - helper to send vblank event after pageflip - * @dev: DRM device - * @pipe: CRTC index + * drm_crtc_send_vblank_event - helper to send vblank event after pageflip + * @crtc: the source CRTC of the vblank event * @e: the event to send * * Updates sequence # and timestamp on event, and sends it to userspace. * Caller must hold event lock. - * - * This is the legacy version of drm_crtc_send_vblank_event(). */ -void drm_send_vblank_event(struct drm_device *dev, unsigned int pipe, - struct drm_pending_vblank_event *e) +void drm_crtc_send_vblank_event(struct drm_crtc *crtc, + struct drm_pending_vblank_event *e) { + struct drm_device *dev = crtc->dev; + unsigned int seq, pipe = drm_crtc_index(crtc); struct timeval now; - unsigned int seq; if (dev->num_crtcs > 0) { seq = drm_vblank_count_and_time(dev, pipe, &now); @@ -1121,23 +1053,6 @@ void drm_send_vblank_event(struct drm_device *dev, unsigned int pipe, e->pipe = pipe; send_vblank_event(dev, e, seq, &now); } -EXPORT_SYMBOL(drm_send_vblank_event); - -/** - * drm_crtc_send_vblank_event - helper to send vblank event after pageflip - * @crtc: the source CRTC of the vblank event - * @e: the event to send - * - * Updates sequence # and timestamp on event, and sends it to userspace. - * Caller must hold event lock. - * - * This is the native KMS version of drm_send_vblank_event(). - */ -void drm_crtc_send_vblank_event(struct drm_crtc *crtc, - struct drm_pending_vblank_event *e) -{ - drm_send_vblank_event(crtc->dev, drm_crtc_index(crtc), e); -} EXPORT_SYMBOL(drm_crtc_send_vblank_event); /** @@ -1193,7 +1108,7 @@ static int drm_vblank_enable(struct drm_device *dev, unsigned int pipe) * Returns: * Zero on success or a negative error code on failure. */ -int drm_vblank_get(struct drm_device *dev, unsigned int pipe) +static int drm_vblank_get(struct drm_device *dev, unsigned int pipe) { struct drm_vblank_crtc *vblank = &dev->vblank[pipe]; unsigned long irqflags; @@ -1219,7 +1134,6 @@ int drm_vblank_get(struct drm_device *dev, unsigned int pipe) return ret; } -EXPORT_SYMBOL(drm_vblank_get); /** * drm_crtc_vblank_get - get a reference count on vblank events @@ -1228,8 +1142,6 @@ EXPORT_SYMBOL(drm_vblank_get); * Acquire a reference count on vblank events to avoid having them disabled * while in use. * - * This is the native kms version of drm_vblank_get(). - * * Returns: * Zero on success or a negative error code on failure. */ @@ -1249,7 +1161,7 @@ EXPORT_SYMBOL(drm_crtc_vblank_get); * * This is the legacy version of drm_crtc_vblank_put(). */ -void drm_vblank_put(struct drm_device *dev, unsigned int pipe) +static void drm_vblank_put(struct drm_device *dev, unsigned int pipe) { struct drm_vblank_crtc *vblank = &dev->vblank[pipe]; @@ -1270,7 +1182,6 @@ void drm_vblank_put(struct drm_device *dev, unsigned int pipe) jiffies + ((drm_vblank_offdelay * HZ)/1000)); } } -EXPORT_SYMBOL(drm_vblank_put); /** * drm_crtc_vblank_put - give up ownership of vblank events @@ -1278,8 +1189,6 @@ EXPORT_SYMBOL(drm_vblank_put); * * Release ownership of a given vblank counter, turning off interrupts * if possible. Disable interrupts after drm_vblank_offdelay milliseconds. - * - * This is the native kms version of drm_vblank_put(). */ void drm_crtc_vblank_put(struct drm_crtc *crtc) { |
