@@ -76,13 +76,15 @@ module_param_named(timestamp_monotonic, drm_timestamp_monotonic, int, 0600);
static void store_vblank(struct drm_device *dev, unsigned int pipe,
u32 vblank_count_inc,
- struct timeval *t_vblank)
+ 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.
*/
@@ -103,6 +105,54 @@ static void store_vblank(struct drm_device *dev, unsigned int pipe,
}
/**
+ * 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.
+ *
+ * Only to be called from drm_vblank_on().
+ *
+ * Note: caller must hold dev->vbl_lock since this reads & writes
+ * device vblank fields.
+ */
+static void drm_reset_vblank_timestamp(struct drm_device *dev, unsigned int pipe)
+{
+ u32 cur_vblank;
+ bool rc;
+ struct timeval t_vblank;
+ int count = DRM_TIMESTAMP_MAXRETRIES;
+
+ spin_lock(&dev->vblank_time_lock);
+
+ /*
+ * sample the current counter to avoid random jumps
+ * when drm_vblank_enable() applies the diff
+ */
+ do {
+ cur_vblank = dev->driver->get_vblank_counter(dev, pipe);
+ rc = drm_get_last_vbltimestamp(dev, pipe, &t_vblank, 0);
+ } while (cur_vblank != dev->driver->get_vblank_counter(dev, pipe) && --count > 0);
+
+ /*
+ * Only reinitialize corresponding vblank timestamp if high-precision query
+ * available and didn't fail. Otherwise reinitialize delayed at next vblank
+ * interrupt and assign 0 for now, to mark the vblanktimestamp as invalid.
+ */
+ if (!rc)
+ t_vblank = (struct timeval) {0, 0};
+
+ /*
+ * +1 to make sure user will never see the same
+ * vblank counter value before and after a modeset
+ */
+ store_vblank(dev, pipe, 1, &t_vblank, cur_vblank);
+
+ spin_unlock(&dev->vblank_time_lock);
+}
+
+/**
* drm_update_vblank_count - update the master vblank counter
* @dev: DRM device
* @pipe: counter to update
@@ -126,6 +176,7 @@ static void drm_update_vblank_count(struct drm_device *dev, unsigned int pipe,
bool rc;
struct timeval t_vblank;
int count = DRM_TIMESTAMP_MAXRETRIES;
+ int framedur_ns = vblank->framedur_ns;
/*
* Interrupts were disabled prior to this call, so deal with counter
@@ -144,20 +195,40 @@ static void drm_update_vblank_count(struct drm_device *dev, unsigned int pipe,
rc = drm_get_last_vbltimestamp(dev, pipe, &t_vblank, flags);
} while (cur_vblank != dev->driver->get_vblank_counter(dev, pipe) && --count > 0);
- /* Deal with counter wrap */
- diff = cur_vblank - vblank->last;
- if (cur_vblank < vblank->last) {
- diff += dev->max_vblank_count + 1;
+ if (dev->max_vblank_count != 0) {
+ /* trust the hw counter when it's around */
+ diff = (cur_vblank - vblank->last) & dev->max_vblank_count;
+ } else if (rc && framedur_ns) {
+ const struct timeval *t_old;
+ u64 diff_ns;
+
+ t_old = &vblanktimestamp(dev, pipe, vblank->count);
+ diff_ns = timeval_to_ns(&t_vblank) - timeval_to_ns(t_old);
- DRM_DEBUG("last_vblank[%u]=0x%x, cur_vblank=0x%x => diff=0x%x\n",
- pipe, vblank->last, cur_vblank, diff);
+ /*
+ * Figure out how many vblanks we've missed based
+ * on the difference in the timestamps and the
+ * frame/field duration.
+ */
+ diff = DIV_ROUND_CLOSEST_ULL(diff_ns, framedur_ns);
+
+ if (diff == 0 && flags & DRM_CALLED_FROM_VBLIRQ)
+ DRM_DEBUG("crtc %u: Redundant vblirq ignored."
+ " diff_ns = %lld, framedur_ns = %d)\n",
+ pipe, (long long) diff_ns, framedur_ns);
+ } else {
+ /* some kind of default for drivers w/o accurate vbl timestamping */
+ diff = (flags & DRM_CALLED_FROM_VBLIRQ) != 0;
}
- DRM_DEBUG("updating vblank count on crtc %u, missed %d\n",
- pipe, diff);
+ DRM_DEBUG("updating vblank count on crtc %u:"
+ " current=%u, diff=%u, hw=%u hw_last=%u\n",
+ pipe, vblank->count, diff, cur_vblank, vblank->last);
- if (diff == 0)
+ if (diff == 0) {
+ WARN_ON_ONCE(cur_vblank != vblank->last);
return;
+ }
/*
* Only reinitialize corresponding vblank timestamp if high-precision query
@@ -167,7 +238,7 @@ static void drm_update_vblank_count(struct drm_device *dev, unsigned int pipe,
if (!rc)
t_vblank = (struct timeval) {0, 0};
- store_vblank(dev, pipe, diff, &t_vblank);
+ store_vblank(dev, pipe, diff, &t_vblank, cur_vblank);
}
/*
@@ -180,11 +251,6 @@ static void vblank_disable_and_save(struct drm_device *dev, unsigned int pipe)
{
struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
unsigned long irqflags;
- u32 vblcount;
- s64 diff_ns;
- bool vblrc;
- struct timeval tvblank;
- int count = DRM_TIMESTAMP_MAXRETRIES;
/* Prevent vblank irq processing while disabling vblank irqs,
* so no updates of timestamps or count can happen after we've
@@ -193,26 +259,6 @@ static void vblank_disable_and_save(struct drm_device *dev, unsigned int pipe)
spin_lock_irqsave(&dev->vblank_time_lock, irqflags);
/*
- * If the vblank interrupt was already disabled update the count
- * and timestamp to maintain the appearance that the counter
- * has been ticking all along until this time. This makes the
- * count account for the entire time between drm_vblank_on() and
- * drm_vblank_off().
- *
- * But only do this if precise vblank timestamps are available.
- * Otherwise we might read a totally bogus timestamp since drivers
- * lacking precise timestamp support rely upon sampling the system clock
- * at vblank interrupt time. Which obviously won't work out well if the
- * vblank interrupt is disabled.
- */
- if (!vblank->enabled &&
- drm_get_last_vbltimestamp(dev, pipe, &tvblank, 0)) {
- drm_update_vblank_count(dev, pipe, 0);
- spin_unlock_irqrestore(&dev->vblank_time_lock, irqflags);
- return;
- }
-
- /*
* Only disable vblank interrupts if they're enabled. This avoids
* calling the ->disable_vblank() operation in atomic context with the
* hardware potentially runtime suspended.
@@ -222,47 +268,13 @@ static void vblank_disable_and_save(struct drm_device *dev, unsigned int pipe)
vblank->enabled = false;
}
- /* No further vblank irq's will be processed after
- * this point. Get current hardware vblank count and
- * vblank timestamp, repeat until they are consistent.
- *
- * FIXME: There is still a race condition here and in
- * drm_update_vblank_count() which can cause off-by-one
- * reinitialization of software vblank counter. If gpu
- * vblank counter doesn't increment exactly at the leading
- * edge of a vblank interval, then we can lose 1 count if
- * we happen to execute between start of vblank and the
- * delayed gpu counter increment.
- */
- do {
- vblank->last = dev->driver->get_vblank_counter(dev, pipe);
- vblrc = drm_get_last_vbltimestamp(dev, pipe, &tvblank, 0);
- } while (vblank->last != dev->driver->get_vblank_counter(dev, pipe) && (--count) && vblrc);
-
- if (!count)
- vblrc = 0;
-
- /* Compute time difference to stored timestamp of last vblank
- * as updated by last invocation of drm_handle_vblank() in vblank irq.
- */
- vblcount = vblank->count;
- diff_ns = timeval_to_ns(&tvblank) -
- timeval_to_ns(&vblanktimestamp(dev, pipe, vblcount));
-
- /* If there is at least 1 msec difference between the last stored
- * timestamp and tvblank, then we are currently executing our
- * disable inside a new vblank interval, the tvblank timestamp
- * corresponds to this new vblank interval and the irq handler
- * for this vblank didn't run yet and won't run due to our disable.
- * Therefore we need to do the job of drm_handle_vblank() and
- * increment the vblank counter by one to account for this vblank.
- *
- * Skip this step if there isn't any high precision timestamp
- * available. In that case we can't account for this and just
- * hope for the best.
+ /*
+ * Always update the count and timestamp to maintain the
+ * appearance that the counter has been ticking all along until
+ * this time. This makes the count account for the entire time
+ * between drm_vblank_on() and drm_vblank_off().
*/
- if (vblrc && (abs64(diff_ns) > 1000000))
- store_vblank(dev, pipe, 1, &tvblank);
+ drm_update_vblank_count(dev, pipe, 0);
spin_unlock_irqrestore(&dev->vblank_time_lock, irqflags);
}
@@ -1325,16 +1337,8 @@ void drm_vblank_on(struct drm_device *dev, unsigned int pipe)
vblank->inmodeset = 0;
}
- /*
- * sample the current counter to avoid random jumps
- * when drm_vblank_enable() applies the diff
- *
- * -1 to make sure user will never see the same
- * vblank counter value before and after a modeset
- */
- vblank->last =
- (dev->driver->get_vblank_counter(dev, pipe) - 1) &
- dev->max_vblank_count;
+ drm_reset_vblank_timestamp(dev, pipe);
+
/*
* re-enable interrupts if there are users left, or the
* user wishes vblank interrupts to be enabled all the time.
@@ -1717,9 +1721,6 @@ static void drm_handle_vblank_events(struct drm_device *dev, unsigned int pipe)
bool drm_handle_vblank(struct drm_device *dev, unsigned int pipe)
{
struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
- u32 vblcount;
- s64 diff_ns;
- struct timeval tvblank;
unsigned long irqflags;
if (WARN_ON_ONCE(!dev->num_crtcs))
@@ -1743,32 +1744,7 @@ bool drm_handle_vblank(struct drm_device *dev, unsigned int pipe)
return false;
}
- /* Fetch corresponding timestamp for this vblank interval from
- * driver and store it in proper slot of timestamp ringbuffer.
- */
-
- /* Get current timestamp and count. */
- vblcount = vblank->count;
- drm_get_last_vbltimestamp(dev, pipe, &tvblank, DRM_CALLED_FROM_VBLIRQ);
-
- /* Compute time difference to timestamp of last vblank */
- diff_ns = timeval_to_ns(&tvblank) -
- timeval_to_ns(&vblanktimestamp(dev, pipe, vblcount));
-
- /* Update vblank timestamp and count if at least
- * DRM_REDUNDANT_VBLIRQ_THRESH_NS nanoseconds
- * difference between last stored timestamp and current
- * timestamp. A smaller difference means basically
- * identical timestamps. Happens if this vblank has
- * been already processed and this is a redundant call,
- * e.g., due to spurious vblank interrupts. We need to
- * ignore those for accounting.
- */
- if (abs64(diff_ns) > DRM_REDUNDANT_VBLIRQ_THRESH_NS)
- store_vblank(dev, pipe, 1, &tvblank);
- else
- DRM_DEBUG("crtc %u: Redundant vblirq ignored. diff_ns = %d\n",
- pipe, (int) diff_ns);
+ drm_update_vblank_count(dev, pipe, DRM_CALLED_FROM_VBLIRQ);
spin_unlock(&dev->vblank_time_lock);