diff options
Diffstat (limited to 'drivers/gpu/drm/drm_irq.c')
| -rw-r--r-- | drivers/gpu/drm/drm_irq.c | 206 |
1 files changed, 91 insertions, 115 deletions
diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c index 07b0cb19c3b5..88fbee4cf4b7 100644 --- a/drivers/gpu/drm/drm_irq.c +++ b/drivers/gpu/drm/drm_irq.c @@ -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); |