[PATCH 03/23] drm/i915: Don't use struct drm_driver.get_scanout_position()

Thomas Zimmermann tzimmermann at suse.de
Fri Jan 10 09:21:07 UTC 2020


The callback struct drm_driver.get_scanout_position() is deprecated in
favor of struct drm_crtc_helper_funcs.get_scanout_position().

i915 doesn't use CRTC helpers. The patch duplicates the caller
drm_calc_vbltimestamp_from_scanoutpos() for i915, such that the callback
function is not needed.

Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
---
 drivers/gpu/drm/i915/i915_drv.c |   3 +-
 drivers/gpu/drm/i915/i915_irq.c | 117 ++++++++++++++++++++++++++++++--
 drivers/gpu/drm/i915/i915_irq.h |   9 +--
 3 files changed, 119 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index f7385abdd74b..4a0a7fb85c53 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -2769,8 +2769,7 @@ static struct drm_driver driver = {
 	.gem_prime_export = i915_gem_prime_export,
 	.gem_prime_import = i915_gem_prime_import,
 
-	.get_vblank_timestamp = drm_calc_vbltimestamp_from_scanoutpos,
-	.get_scanout_position = i915_get_crtc_scanoutpos,
+	.get_vblank_timestamp = i915_calc_vbltimestamp_from_scanoutpos,
 
 	.dumb_create = i915_gem_dumb_create,
 	.dumb_map_offset = i915_gem_dumb_mmap_offset,
diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index afc6aad9bf8c..99d0c3b0feae 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -52,6 +52,11 @@
 #include "i915_trace.h"
 #include "intel_pm.h"
 
+/* Retry timestamp calculation up to 3 times to satisfy
+ * drm_timestamp_precision before giving up.
+ */
+#define I915_TIMESTAMP_MAXRETRIES 3
+
 /**
  * DOC: interrupt handling
  *
@@ -762,10 +767,11 @@ static int __intel_get_crtc_scanline(struct intel_crtc *crtc)
 	return (position + crtc->scanline_offset) % vtotal;
 }
 
-bool i915_get_crtc_scanoutpos(struct drm_device *dev, unsigned int index,
-			      bool in_vblank_irq, int *vpos, int *hpos,
-			      ktime_t *stime, ktime_t *etime,
-			      const struct drm_display_mode *mode)
+static bool i915_get_crtc_scanoutpos(struct drm_device *dev,
+				     unsigned int index, bool in_vblank_irq,
+				     int *vpos, int *hpos,
+				     ktime_t *stime, ktime_t *etime,
+				     const struct drm_display_mode *mode)
 {
 	struct drm_i915_private *dev_priv = to_i915(dev);
 	struct intel_crtc *crtc = to_intel_crtc(drm_crtc_from_index(dev, index));
@@ -879,6 +885,109 @@ bool i915_get_crtc_scanoutpos(struct drm_device *dev, unsigned int index,
 	return true;
 }
 
+bool i915_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev,
+					    unsigned int pipe,
+					    int *max_error,
+					    ktime_t *vblank_time,
+					    bool in_vblank_irq)
+{
+	struct timespec64 ts_etime, ts_vblank_time;
+	ktime_t stime, etime;
+	bool vbl_status;
+	struct drm_crtc *crtc;
+	const struct drm_display_mode *mode;
+	struct drm_vblank_crtc *vblank = &dev->vblank[pipe];
+	int vpos, hpos, i;
+	int delta_ns, duration_ns;
+
+	crtc = drm_crtc_from_index(dev, pipe);
+
+	if (pipe >= dev->num_crtcs || !crtc) {
+		DRM_ERROR("Invalid crtc %u\n", pipe);
+		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 < I915_TIMESTAMP_MAXRETRIES; i++) {
+		/*
+		 * Get vertical and horizontal scanout position vpos, hpos,
+		 * and bounding timestamps stime, etime, pre/post query.
+		 */
+		vbl_status = i915_get_crtc_scanoutpos(dev, pipe, 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 == I915_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;
+}
+
 int intel_get_crtc_scanline(struct intel_crtc *crtc)
 {
 	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
diff --git a/drivers/gpu/drm/i915/i915_irq.h b/drivers/gpu/drm/i915/i915_irq.h
index 812c47a9c2d6..5f7b133ce721 100644
--- a/drivers/gpu/drm/i915/i915_irq.h
+++ b/drivers/gpu/drm/i915/i915_irq.h
@@ -101,10 +101,11 @@ void gen8_irq_power_well_post_enable(struct drm_i915_private *dev_priv,
 void gen8_irq_power_well_pre_disable(struct drm_i915_private *dev_priv,
 				     u8 pipe_mask);
 
-bool i915_get_crtc_scanoutpos(struct drm_device *dev, unsigned int pipe,
-			      bool in_vblank_irq, int *vpos, int *hpos,
-			      ktime_t *stime, ktime_t *etime,
-			      const struct drm_display_mode *mode);
+bool i915_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev,
+					    unsigned int pipe,
+					    int *max_error,
+					    ktime_t *vblank_time,
+					    bool in_vblank_irq);
 
 u32 i915_get_vblank_counter(struct drm_crtc *crtc);
 u32 g4x_get_vblank_counter(struct drm_crtc *crtc);
-- 
2.24.1



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