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 <tzimmerm...@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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