Hi Am 15.01.20 um 15:49 schrieb Ville Syrjälä: > On Wed, Jan 15, 2020 at 01:16:34PM +0100, Thomas Zimmermann wrote: >> 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)) { > > Could drop the superfluous parens while at it. > > Are all drivers utilizing this guaranteed to have the crtc here? Good point. This is part of the suspend and resume code. I don't think it's possible to run this code without creating a CRTC. But it's also called from drm_legacy_vblank_post_modeset(), which does not have CRTCs. Legacy drivers don't implement get_vblank_timestamp() at all. I think we can skip this entire block for legacy drivers. > >> + 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) > > Here you are expecting that the crtc might be NULL. Because of legacy drivers. > >> + 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; > > Here again assuming the crtc can't be NULL. There should probably be a check to handle legacy devices correctly. > >> + >> + 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); > > This looks like copy paste from the current thing. Why are you > duplicating the entire function instead of refactoring what > we already have? It is copied with a small difference. The original function is drm_calc_vbltimestamp_from_scanoutpos(). It uses either drm_driver.get_scanout_position() or drm_crtc_helper_funcs.get_scanout_position(). The former receives device pointer and pipe index, the latter receives a pointer to a crtc. (see patch 1) This function, drm_crtc_vblank_helper_get_vblank_timestamp_internal(), receives a get_scanout_position() as its argument with the same signature as drm_crtc_helper_funcs.get_scanout_position(). The function is exported, so that i915 can use the algorithm and provide it's own implementation of get_scanout_position(). i915 does not use CRTC helpers, and therefore cannot set get_scanout_position() there. Patch 21, when all drivers have been converted to use the CRTC interface, removes drm_calc_vbltimestamp_from_scanoutpos() entirely. It's only kept around for transitionng the driver over to the new interface. > >> + >> +/** >> + * 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)); > > Ugly alignment. Could maybe add a typedef for the function pointer if it > otherwise gets super horrible with proper alignment. Email formatting might add to the ugliness here. How would this be aligned properly? I'm slightly reluctent to add a typedef for only this single function and it's caller in i915. Typedefs are a form of code obfuscation IMHO. But if that's the way to go, I won't mind of course. Best regards Thomas > >> +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 >> >> _______________________________________________ >> Intel-gfx mailing list >> Intel-gfx@xxxxxxxxxxxxxxxxxxxxx >> https://lists.freedesktop.org/mailman/listinfo/intel-gfx > -- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Felix Imendörffer
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