[PATCH v2 03/21] drm: Add get_vblank_timestamp() to struct drm_crtc_funcs
Thomas Zimmermann
tzimmermann at suse.de
Wed Jan 15 12:16:34 UTC 2020
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 at suse.de>
---
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
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