The callback get_vblank_timestamp() is currently located in struct drm_driver, but really belongs into struct drm_crtc_funcs. Add an equivalent there. Driver will be converted in separate patches. The default implementation is drm_calc_vbltimestamp_from_scanoutpos(). The patch adds drm_crtc_vblank_helper_get_vblank_timestamp(), which is an implementation for the CRTC callback. v2: * rename helper to drm_crtc_vblank_helper_get_vblank_timestamp() * replace drm_calc_vbltimestamp_from_scanoutpos() with drm_crtc_vblank_helper_get_vblank_timestamp() in docs Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx> --- drivers/gpu/drm/drm_vblank.c | 236 +++++++++++++++++++++-- include/drm/drm_crtc.h | 46 ++++- include/drm/drm_modeset_helper_vtables.h | 4 +- include/drm/drm_vblank.h | 26 ++- 4 files changed, 292 insertions(+), 20 deletions(-) diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c index abb085c67d82..1b7af316e6a5 100644 --- a/drivers/gpu/drm/drm_vblank.c +++ b/drivers/gpu/drm/drm_vblank.c @@ -333,7 +333,9 @@ u64 drm_crtc_accurate_vblank_count(struct drm_crtc *crtc) u64 vblank; unsigned long flags; - WARN_ONCE(drm_debug_enabled(DRM_UT_VBL) && !dev->driver->get_vblank_timestamp, + WARN_ONCE(drm_debug_enabled(DRM_UT_VBL) && + !crtc->funcs->get_vblank_timestamp && + !dev->driver->get_vblank_timestamp, "This function requires support for accurate vblank timestamps."); spin_lock_irqsave(&dev->vblank_time_lock, flags); @@ -511,9 +513,9 @@ EXPORT_SYMBOL(drm_crtc_vblank_waitqueue); * * Calculate and store various constants which are later needed by vblank and * swap-completion timestamping, e.g, by - * drm_calc_vbltimestamp_from_scanoutpos(). They are derived from CRTC's true - * scanout timing, so they take things like panel scaling or other adjustments - * into account. + * drm_crtc_vblank_helper_get_vblank_timestamp(). They are derived from + * CRTC's true scanout timing, so they take things like panel scaling or + * other adjustments into account. */ void drm_calc_timestamping_constants(struct drm_crtc *crtc, const struct drm_display_mode *mode) @@ -577,8 +579,9 @@ EXPORT_SYMBOL(drm_calc_timestamping_constants); * * Implements calculation of exact vblank timestamps from given drm_display_mode * timings and current video scanout position of a CRTC. This can be directly - * used as the &drm_driver.get_vblank_timestamp implementation of a kms driver - * if &drm_crtc_helper_funcs.get_scanout_position is implemented. + * used as the &drm_crtc_funcs.get_vblank_timestamp implementation of a kms + * driver if &drm_crtc_helper_funcs.get_scanout_position or + * &drm_driver.get_scanout_position is implemented. * * The current implementation only handles standard video modes. For double scan * and interlaced modes the driver is supposed to adjust the hardware mode @@ -742,15 +745,22 @@ static bool drm_get_last_vbltimestamp(struct drm_device *dev, unsigned int pipe, ktime_t *tvblank, bool in_vblank_irq) { + struct drm_crtc *crtc = drm_crtc_from_index(dev, pipe); bool ret = false; /* Define requested maximum error on timestamps (nanoseconds). */ int max_error = (int) drm_timestamp_precision * 1000; /* Query driver if possible and precision timestamping enabled. */ - if (dev->driver->get_vblank_timestamp && (max_error > 0)) + if (crtc->funcs->get_vblank_timestamp && (max_error > 0)) { + struct drm_crtc *crtc = drm_crtc_from_index(dev, pipe); + + ret = crtc->funcs->get_vblank_timestamp(crtc, &max_error, + tvblank, in_vblank_irq); + } else if (dev->driver->get_vblank_timestamp && (max_error > 0)) { ret = dev->driver->get_vblank_timestamp(dev, pipe, &max_error, tvblank, in_vblank_irq); + } /* GPU high precision timestamp query unsupported or failed. * Return current monotonic/gettimeofday timestamp as best estimate. @@ -1059,11 +1069,19 @@ EXPORT_SYMBOL(drm_crtc_vblank_get); static bool __vblank_disable_immediate(struct drm_device *dev, unsigned int pipe) { + struct drm_crtc *crtc; + if (!dev->vblank_disable_immediate) return false; - if (!dev->driver->get_vblank_timestamp) - return false; - return true; + + crtc = drm_crtc_from_index(dev, pipe); + if (crtc && crtc->funcs->get_vblank_timestamp) + return true; + + if (dev->driver->get_vblank_timestamp) + return true; + + return false; } static void drm_vblank_put(struct drm_device *dev, unsigned int pipe) @@ -1742,9 +1760,11 @@ int drm_wait_vblank_ioctl(struct drm_device *dev, void *data, static void drm_handle_vblank_events(struct drm_device *dev, unsigned int pipe) { + struct drm_crtc *crtc = drm_crtc_from_index(dev, pipe); struct drm_pending_vblank_event *e, *t; ktime_t now; u64 seq; + bool high_prec; assert_spin_locked(&dev->event_lock); @@ -1764,8 +1784,10 @@ static void drm_handle_vblank_events(struct drm_device *dev, unsigned int pipe) send_vblank_event(dev, e, seq, now); } - trace_drm_vblank_event(pipe, seq, now, - dev->driver->get_vblank_timestamp != NULL); + high_prec = crtc->funcs->get_vblank_timestamp || + dev->driver->get_vblank_timestamp; + + trace_drm_vblank_event(pipe, seq, now, high_prec); } /** @@ -2020,3 +2042,193 @@ int drm_crtc_queue_sequence_ioctl(struct drm_device *dev, void *data, kfree(e); return ret; } + +/* + * Helpers for struct drm_crtc_funcs + */ + +/** + * drm_crtc_vblank_helper_get_vblank_timestamp_internal - precise vblank + * timestamp helper + * @dev: DRM device + * @pipe: index of CRTC whose vblank timestamp to retrieve + * @max_error: Desired maximum allowable error in timestamps (nanosecs) + * On return contains true maximum error of timestamp + * @vblank_time: Pointer to time which should receive the timestamp + * @in_vblank_irq: + * True when called from drm_crtc_handle_vblank(). Some drivers + * need to apply some workarounds for gpu-specific vblank irq quirks + * if flag is set. + * @get_scanout_position: + * Callback function to retrieve the scanout position. See + * @struct drm_crtc_helper_funcs.get_scanout_position. + * + * Implements calculation of exact vblank timestamps from given drm_display_mode + * timings and current video scanout position of a CRTC. + * + * The current implementation only handles standard video modes. For double scan + * and interlaced modes the driver is supposed to adjust the hardware mode + * (taken from &drm_crtc_state.adjusted mode for atomic modeset drivers) to + * match the scanout position reported. + * + * Note that atomic drivers must call drm_calc_timestamping_constants() before + * enabling a CRTC. The atomic helpers already take care of that in + * drm_atomic_helper_update_legacy_modeset_state(). + * + * Returns: + * + * Returns true on success, and false on failure, i.e. when no accurate + * timestamp could be acquired. + */ +bool +drm_crtc_vblank_helper_get_vblank_timestamp_internal( + struct drm_crtc *crtc, int *max_error, ktime_t *vblank_time, + bool in_vblank_irq, + bool (*get_scanout_position)(struct drm_crtc *crtc, + bool in_vblank_irq, int *vpos, int *hpos, + ktime_t *stime, ktime_t *etime, + const struct drm_display_mode *mode)) +{ + struct drm_device *dev = crtc->dev; + unsigned int pipe = crtc->index; + struct drm_vblank_crtc *vblank = &dev->vblank[pipe]; + struct timespec64 ts_etime, ts_vblank_time; + ktime_t stime, etime; + bool vbl_status; + const struct drm_display_mode *mode; + int vpos, hpos, i; + int delta_ns, duration_ns; + + if (pipe >= dev->num_crtcs) { + DRM_ERROR("Invalid crtc %u\n", pipe); + return false; + } + + /* Scanout position query not supported? Should not happen. */ + if (!get_scanout_position) { + DRM_ERROR("Called from CRTC w/o get_scanout_position()!?\n"); + return false; + } + + if (drm_drv_uses_atomic_modeset(dev)) + mode = &vblank->hwmode; + else + mode = &crtc->hwmode; + + /* If mode timing undefined, just return as no-op: + * Happens during initial modesetting of a crtc. + */ + if (mode->crtc_clock == 0) { + DRM_DEBUG("crtc %u: Noop due to uninitialized mode.\n", pipe); + WARN_ON_ONCE(drm_drv_uses_atomic_modeset(dev)); + return false; + } + + /* Get current scanout position with system timestamp. + * Repeat query up to DRM_TIMESTAMP_MAXRETRIES times + * if single query takes longer than max_error nanoseconds. + * + * This guarantees a tight bound on maximum error if + * code gets preempted or delayed for some reason. + */ + for (i = 0; i < DRM_TIMESTAMP_MAXRETRIES; i++) { + /* + * Get vertical and horizontal scanout position vpos, hpos, + * and bounding timestamps stime, etime, pre/post query. + */ + vbl_status = get_scanout_position(crtc, in_vblank_irq, &vpos, + &hpos, &stime, &etime, mode); + + /* Return as no-op if scanout query unsupported or failed. */ + if (!vbl_status) { + DRM_DEBUG("crtc %u : scanoutpos query failed.\n", + pipe); + return false; + } + + /* Compute uncertainty in timestamp of scanout position query. */ + duration_ns = ktime_to_ns(etime) - ktime_to_ns(stime); + + /* Accept result with < max_error nsecs timing uncertainty. */ + if (duration_ns <= *max_error) + break; + } + + /* Noisy system timing? */ + if (i == DRM_TIMESTAMP_MAXRETRIES) { + DRM_DEBUG("crtc %u: Noisy timestamp %d us > %d us [%d reps].\n", + pipe, duration_ns/1000, *max_error/1000, i); + } + + /* Return upper bound of timestamp precision error. */ + *max_error = duration_ns; + + /* Convert scanout position into elapsed time at raw_time query + * since start of scanout at first display scanline. delta_ns + * can be negative if start of scanout hasn't happened yet. + */ + delta_ns = div_s64(1000000LL * (vpos * mode->crtc_htotal + hpos), + mode->crtc_clock); + + /* Subtract time delta from raw timestamp to get final + * vblank_time timestamp for end of vblank. + */ + *vblank_time = ktime_sub_ns(etime, delta_ns); + + if (!drm_debug_enabled(DRM_UT_VBL)) + return true; + + ts_etime = ktime_to_timespec64(etime); + ts_vblank_time = ktime_to_timespec64(*vblank_time); + + DRM_DEBUG_VBL("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, + duration_ns / 1000, i); + + return true; +} +EXPORT_SYMBOL(drm_crtc_vblank_helper_get_vblank_timestamp_internal); + +/** + * drm_crtc_vblank_helper_get_vblank_timestamp - precise vblank timestamp + * helper + * @crtc: CRTC whose vblank timestamp to retrieve + * @max_error: Desired maximum allowable error in timestamps (nanosecs) + * On return contains true maximum error of timestamp + * @vblank_time: Pointer to time which should receive the timestamp + * @in_vblank_irq: + * True when called from drm_crtc_handle_vblank(). Some drivers + * need to apply some workarounds for gpu-specific vblank irq quirks + * if flag is set. + * + * Implements calculation of exact vblank timestamps from given drm_display_mode + * timings and current video scanout position of a CRTC. This can be directly + * used as the &drm_crtc_funcs.get_vblank_timestamp implementation of a kms + * driver if &drm_crtc_helper_funcs.get_scanout_position is implemented. + * + * The current implementation only handles standard video modes. For double scan + * and interlaced modes the driver is supposed to adjust the hardware mode + * (taken from &drm_crtc_state.adjusted mode for atomic modeset drivers) to + * match the scanout position reported. + * + * Note that atomic drivers must call drm_calc_timestamping_constants() before + * enabling a CRTC. The atomic helpers already take care of that in + * drm_atomic_helper_update_legacy_modeset_state(). + * + * Returns: + * + * Returns true on success, and false on failure, i.e. when no accurate + * timestamp could be acquired. + */ +bool drm_crtc_vblank_helper_get_vblank_timestamp(struct drm_crtc *crtc, + int *max_error, + ktime_t *vblank_time, + bool in_vblank_irq) +{ + return drm_crtc_vblank_helper_get_vblank_timestamp_internal( + crtc, max_error, vblank_time, in_vblank_irq, + crtc->helper_private->get_scanout_position); +} +EXPORT_SYMBOL(drm_crtc_vblank_helper_get_vblank_timestamp); diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h index 5e9b15a0e8c5..db46abbbf4e7 100644 --- a/include/drm/drm_crtc.h +++ b/include/drm/drm_crtc.h @@ -867,6 +867,47 @@ struct drm_crtc_funcs { * new drivers as the replacement of &drm_driver.disable_vblank hook. */ void (*disable_vblank)(struct drm_crtc *crtc); + + /** + * @get_vblank_timestamp: + * + * Called by drm_get_last_vbltimestamp(). Should return a precise + * timestamp when the most recent vblank interval ended or will end. + * + * Specifically, the timestamp in @vblank_time should correspond as + * closely as possible to the time when the first video scanline of + * the video frame after the end of vblank will start scanning out, + * the time immediately after end of the vblank interval. If the + * @crtc is currently inside vblank, this will be a time in the future. + * If the @crtc is currently scanning out a frame, this will be the + * past start time of the current scanout. This is meant to adhere + * to the OpenML OML_sync_control extension specification. + * + * Parameters: + * + * crtc: + * CRTC for which timestamp should be returned. + * max_error: + * Maximum allowable timestamp error in nanoseconds. + * Implementation should strive to provide timestamp + * with an error of at most max_error nanoseconds. + * Returns true upper bound on error for timestamp. + * vblank_time: + * Target location for returned vblank timestamp. + * in_vblank_irq: + * True when called from drm_crtc_handle_vblank(). Some drivers + * need to apply some workarounds for gpu-specific vblank irq quirks + * if flag is set. + * + * Returns: + * + * True on success, false on failure, which means the core should + * fallback to a simple timestamp taken in drm_crtc_handle_vblank(). + */ + bool (*get_vblank_timestamp)(struct drm_crtc *crtc, + int *max_error, + ktime_t *vblank_time, + bool in_vblank_irq); }; /** @@ -974,11 +1015,12 @@ struct drm_crtc { * Programmed mode in hw, after adjustments for encoders, crtc, panel * scaling etc. Should only be used by legacy drivers, for high * precision vblank timestamps in - * drm_calc_vbltimestamp_from_scanoutpos(). + * drm_crtc_vblank_helper_get_vblank_timestamp(). * * Note that atomic drivers should not use this, but instead use * &drm_crtc_state.adjusted_mode. And for high-precision timestamps - * drm_calc_vbltimestamp_from_scanoutpos() used &drm_vblank_crtc.hwmode, + * drm_crtc_vblank_helper_get_vblank_timestamp() used + * &drm_vblank_crtc.hwmode, * which is filled out by calling drm_calc_timestamping_constants(). */ struct drm_display_mode hwmode; diff --git a/include/drm/drm_modeset_helper_vtables.h b/include/drm/drm_modeset_helper_vtables.h index e398512bfd5f..0afaf58da40d 100644 --- a/include/drm/drm_modeset_helper_vtables.h +++ b/include/drm/drm_modeset_helper_vtables.h @@ -459,8 +459,8 @@ struct drm_crtc_helper_funcs { * Returns the current display scanout position from a CRTC and an * optional accurate ktime_get() timestamp of when the position was * measured. Note that this is a helper callback which is only used - * if a driver uses drm_calc_vbltimestamp_from_scanoutpos() for the - * @drm_driver.get_vblank_timestamp callback. + * if a driver uses drm_crtc_vblank_helper_get_vblank_timestamp() + * for the @drm_crtc_funcs.get_vblank_timestamp callback. * * Parameters: * diff --git a/include/drm/drm_vblank.h b/include/drm/drm_vblank.h index c16c44052b3d..248fbd5de177 100644 --- a/include/drm/drm_vblank.h +++ b/include/drm/drm_vblank.h @@ -174,13 +174,13 @@ struct drm_vblank_crtc { unsigned int pipe; /** * @framedur_ns: Frame/Field duration in ns, used by - * drm_calc_vbltimestamp_from_scanoutpos() and computed by + * drm_crtc_vblank_helper_get_vblank_timestamp() and computed by * drm_calc_timestamping_constants(). */ int framedur_ns; /** * @linedur_ns: Line duration in ns, used by - * drm_calc_vbltimestamp_from_scanoutpos() and computed by + * drm_crtc_vblank_helper_get_vblank_timestamp() and computed by * drm_calc_timestamping_constants(). */ int linedur_ns; @@ -190,8 +190,8 @@ struct drm_vblank_crtc { * * Cache of the current hardware display mode. Only valid when @enabled * is set. This is used by helpers like - * drm_calc_vbltimestamp_from_scanoutpos(). We can't just access the - * hardware mode by e.g. looking at &drm_crtc_state.adjusted_mode, + * drm_crtc_vblank_helper_get_vblank_timestamp(). We can't just access + * the hardware mode by e.g. looking at &drm_crtc_state.adjusted_mode, * because that one is really hard to get from interrupt context. */ struct drm_display_mode hwmode; @@ -238,4 +238,22 @@ void drm_calc_timestamping_constants(struct drm_crtc *crtc, 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); + +/* + * Helpers for struct drm_crtc_funcs + */ + +bool +drm_crtc_vblank_helper_get_vblank_timestamp_internal( + struct drm_crtc *crtc, int *max_error, ktime_t *vblank_time, + bool in_vblank_irq, + bool (*get_scanout_position)(struct drm_crtc *crtc, + bool in_vblank_irq, int *vpos, int *hpos, + ktime_t *stime, ktime_t *etime, + const struct drm_display_mode *mode)); +bool drm_crtc_vblank_helper_get_vblank_timestamp(struct drm_crtc *crtc, + int *max_error, + ktime_t *vblank_time, + bool in_vblank_irq); + #endif -- 2.24.1