diff options
| -rw-r--r-- | drivers/gpu/drm/drm_vblank.c | 45 | ||||
| -rw-r--r-- | include/drm/drm_device.h | 6 | ||||
| -rw-r--r-- | include/drm/drm_vblank.h | 22 |
3 files changed, 70 insertions, 3 deletions
diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c index 98e091175921..cde71ee95a8f 100644 --- a/drivers/gpu/drm/drm_vblank.c +++ b/drivers/gpu/drm/drm_vblank.c @@ -105,13 +105,20 @@ static void store_vblank(struct drm_device *dev, unsigned int pipe, write_sequnlock(&vblank->seqlock); } +static u32 drm_max_vblank_count(struct drm_device *dev, unsigned int pipe) +{ + struct drm_vblank_crtc *vblank = &dev->vblank[pipe]; + + return vblank->max_vblank_count ?: dev->max_vblank_count; +} + /* * "No hw counter" fallback implementation of .get_vblank_counter() hook, * if there is no useable hardware frame counter available. */ static u32 drm_vblank_no_hw_counter(struct drm_device *dev, unsigned int pipe) { - WARN_ON_ONCE(dev->max_vblank_count != 0); + WARN_ON_ONCE(drm_max_vblank_count(dev, pipe) != 0); return 0; } @@ -198,6 +205,7 @@ static void drm_update_vblank_count(struct drm_device *dev, unsigned int pipe, ktime_t t_vblank; int count = DRM_TIMESTAMP_MAXRETRIES; int framedur_ns = vblank->framedur_ns; + u32 max_vblank_count = drm_max_vblank_count(dev, pipe); /* * Interrupts were disabled prior to this call, so deal with counter @@ -216,9 +224,9 @@ static void drm_update_vblank_count(struct drm_device *dev, unsigned int pipe, rc = drm_get_last_vbltimestamp(dev, pipe, &t_vblank, in_vblank_irq); } while (cur_vblank != __get_vblank_counter(dev, pipe) && --count > 0); - if (dev->max_vblank_count != 0) { + if (max_vblank_count) { /* trust the hw counter when it's around */ - diff = (cur_vblank - vblank->last) & dev->max_vblank_count; + diff = (cur_vblank - vblank->last) & max_vblank_count; } else if (rc && framedur_ns) { u64 diff_ns = ktime_to_ns(ktime_sub(t_vblank, vblank->time)); @@ -1205,6 +1213,37 @@ void drm_crtc_vblank_reset(struct drm_crtc *crtc) EXPORT_SYMBOL(drm_crtc_vblank_reset); /** + * drm_crtc_set_max_vblank_count - configure the hw max vblank counter value + * @crtc: CRTC in question + * @max_vblank_count: max hardware vblank counter value + * + * Update the maximum hardware vblank counter value for @crtc + * at runtime. Useful for hardware where the operation of the + * hardware vblank counter depends on the currently active + * display configuration. + * + * For example, if the hardware vblank counter does not work + * when a specific connector is active the maximum can be set + * to zero. And when that specific connector isn't active the + * maximum can again be set to the appropriate non-zero value. + * + * If used, must be called before drm_vblank_on(). + */ +void drm_crtc_set_max_vblank_count(struct drm_crtc *crtc, + u32 max_vblank_count) +{ + struct drm_device *dev = crtc->dev; + unsigned int pipe = drm_crtc_index(crtc); + struct drm_vblank_crtc *vblank = &dev->vblank[pipe]; + + WARN_ON(dev->max_vblank_count); + WARN_ON(!READ_ONCE(vblank->inmodeset)); + + vblank->max_vblank_count = max_vblank_count; +} +EXPORT_SYMBOL(drm_crtc_set_max_vblank_count); + +/** * drm_crtc_vblank_on - enable vblank events on a CRTC * @crtc: CRTC in question * diff --git a/include/drm/drm_device.h b/include/drm/drm_device.h index a6f8e5abb66f..d5e092dccf3e 100644 --- a/include/drm/drm_device.h +++ b/include/drm/drm_device.h @@ -240,6 +240,12 @@ struct drm_device { * races and imprecision over longer time periods, hence exposing a * hardware vblank counter is always recommended. * + * This is the statically configured device wide maximum. The driver + * can instead choose to use a runtime configurable per-crtc value + * &drm_vblank_crtc.max_vblank_count, in which case @max_vblank_count + * must be left at zero. See drm_crtc_set_max_vblank_count() on how + * to use the per-crtc value. + * * If non-zero, &drm_crtc_funcs.get_vblank_counter must be set. */ u32 max_vblank_count; diff --git a/include/drm/drm_vblank.h b/include/drm/drm_vblank.h index 6ad9630d4f48..e528bb2f659d 100644 --- a/include/drm/drm_vblank.h +++ b/include/drm/drm_vblank.h @@ -129,6 +129,26 @@ struct drm_vblank_crtc { */ u32 last; /** + * @max_vblank_count: + * + * Maximum value of the vblank registers for this crtc. This value +1 + * will result in a wrap-around of the vblank register. It is used + * by the vblank core to handle wrap-arounds. + * + * If set to zero the vblank core will try to guess the elapsed vblanks + * between times when the vblank interrupt is disabled through + * high-precision timestamps. That approach is suffering from small + * races and imprecision over longer time periods, hence exposing a + * hardware vblank counter is always recommended. + * + * This is the runtime configurable per-crtc maximum set through + * drm_crtc_set_max_vblank_count(). If this is used the driver + * must leave the device wide &drm_device.max_vblank_count at zero. + * + * If non-zero, &drm_crtc_funcs.get_vblank_counter must be set. + */ + u32 max_vblank_count; + /** * @inmodeset: Tracks whether the vblank is disabled due to a modeset. * For legacy driver bit 2 additionally tracks whether an additional * temporary vblank reference has been acquired to paper over the @@ -206,4 +226,6 @@ bool drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev, void drm_calc_timestamping_constants(struct drm_crtc *crtc, const struct drm_display_mode *mode); wait_queue_head_t *drm_crtc_vblank_waitqueue(struct drm_crtc *crtc); +void drm_crtc_set_max_vblank_count(struct drm_crtc *crtc, + u32 max_vblank_count); #endif |