drm/vblank: drop the mode argument from drm_calc_vbltimestamp_from_scanoutpos

If we restrict this helper to only kms drivers (which is the case) we
can look up the correct mode easily ourselves. But it's a bit tricky:

- All legacy drivers look at crtc->hwmode. But that is updated already
at the beginning of the modeset helper, which means when we disable
a pipe. Hence the final timestamps might be a bit off. But since
this is an existing bug I'm not going to change it, but just try to
be bug-for-bug compatible with the current code. This only applies
to radeon&amdgpu.

- i915 tries to get it perfect by updating crtc->hwmode when the pipe
is off (i.e. vblank->enabled = false).

- All other atomic drivers look at crtc->state->adjusted_mode. Those
that look at state->requested_mode simply don't adjust their mode,
so it's the same. That has two problems: Accessing crtc->state from
interrupt handling code is unsafe, and it's updated before we shut
down the pipe. For nonblocking modesets it's even worse.

For atomic drivers try to implement what i915 does. To do that we add
a new hwmode field to the vblank structure, and update it from
drm_calc_timestamping_constants(). For atomic drivers that's called
from the right spot by the helper library already, so all fine. But
for safety let's enforce that.

For legacy driver this function is only called at the end (oh the
fun), which is broken, so again let's not bother and just stay
bug-for-bug compatible.

The benefit is that we can use drm_calc_vbltimestamp_from_scanoutpos
directly to implement ->get_vblank_timestamp in every driver, deleting
a lot of code.

v2: Completely new approach, trying to mimick the i915 solution.

v3: Fixup kerneldoc.

v4: Drop the WARN_ON to check that the vblank is off, atomic helpers
currently unconditionally call this. Recomputing the same stuff should
be harmless.

v5: Fix typos and move misplaced hunks to the right patches (Neil).

v6: Undo hunk movement (kbuild).

Cc: Mario Kleiner <[e-mail]>
Cc: Eric Anholt <[e-mail]>
Cc: Rob Clark <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Cc: Alex Deucher <[e-mail]>
Cc: Christian König <[e-mail]>
Cc: Ben Skeggs <[e-mail]>
Reviewed-by: Neil Armstrong <[e-mail]>
Acked-by: Ville Syrjälä <[e-mail]>
Signed-off-by: Daniel Vetter <[e-mail]>
Link: http://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/amd/amdgpu/amdgpu.h

···
 u32 amdgpu_get_vblank_counter_kms(struct drm_device *dev, unsigned int pipe);
 int amdgpu_enable_vblank_kms(struct drm_device *dev, unsigned int pipe);
 void amdgpu_disable_vblank_kms(struct drm_device *dev, unsigned int pipe);
-bool amdgpu_get_vblank_timestamp_kms(struct drm_device *dev, unsigned int pipe,
-				     int *max_error,
-				     struct timeval *vblank_time,
-				     bool in_vblank_irq);
 long amdgpu_kms_compat_ioctl(struct file *filp, unsigned int cmd,
 			     unsigned long arg);
 

drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c

···
 #endif
 };
 
+static bool
+amdgpu_get_crtc_scanout_position(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)
+{
+	return amdgpu_get_crtc_scanoutpos(dev, pipe, 0, vpos, hpos,
+					  stime, etime, mode);
+}
+
 static struct drm_driver kms_driver = {
 	.driver_features =
 	    DRIVER_USE_AGP |
···
 	.get_vblank_counter = amdgpu_get_vblank_counter_kms,
 	.enable_vblank = amdgpu_enable_vblank_kms,
 	.disable_vblank = amdgpu_disable_vblank_kms,
-	.get_vblank_timestamp = amdgpu_get_vblank_timestamp_kms,
-	.get_scanout_position = amdgpu_get_crtc_scanoutpos,
+	.get_vblank_timestamp = drm_calc_vbltimestamp_from_scanoutpos,
+	.get_scanout_position = amdgpu_get_crtc_scanout_position,
 #if defined(CONFIG_DEBUG_FS)
 	.debugfs_init = amdgpu_debugfs_init,
 #endif

drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c

···
 	amdgpu_irq_put(adev, &adev->crtc_irq, idx);
 }
 
-/**
- * amdgpu_get_vblank_timestamp_kms - get vblank timestamp
- *
- * @dev: drm dev pointer
- * @crtc: crtc to get the timestamp for
- * @max_error: max error
- * @vblank_time: time value
- * @in_vblank_irq: called from drm_handle_vblank()
- *
- * Gets the timestamp on the requested crtc based on the
- * scanout position.  (all asics).
- * Returns true on success, false on failure.
- */
-bool amdgpu_get_vblank_timestamp_kms(struct drm_device *dev, unsigned int pipe,
-				     int *max_error,
-				     struct timeval *vblank_time,
-				     bool in_vblank_irq)
-{
-	struct drm_crtc *crtc;
-	struct amdgpu_device *adev = dev->dev_private;
-
-	if (pipe >= dev->num_crtcs) {
-		DRM_ERROR("Invalid crtc %u\n", pipe);
-		return false;
-	}
-
-	/* Get associated drm_crtc: */
-	crtc = &adev->mode_info.crtcs[pipe]->base;
-	if (!crtc) {
-		/* This can occur on driver load if some component fails to
-		 * initialize completely and driver is unloaded */
-		DRM_ERROR("Uninitialized crtc %d\n", pipe);
-		return false;
-	}
-
-	/* Helper routine in DRM core does all the work: */
-	return drm_calc_vbltimestamp_from_scanoutpos(dev, pipe, max_error,
-						     vblank_time, in_vblank_irq,
-						     &crtc->hwmode);
-}
-
 const struct drm_ioctl_desc amdgpu_ioctls_kms[] = {
 	DRM_IOCTL_DEF_DRV(AMDGPU_GEM_CREATE, amdgpu_gem_create_ioctl, DRM_AUTH|DRM_RENDER_ALLOW),
 	DRM_IOCTL_DEF_DRV(AMDGPU_CTX, amdgpu_ctx_ioctl, DRM_AUTH|DRM_RENDER_ALLOW),

drivers/gpu/drm/amd/amdgpu/amdgpu_mode.h

···
 				((em) == ATOM_ENCODER_MODE_DP_MST))
 
 /* Driver internal use only flags of amdgpu_get_crtc_scanoutpos() */
+#define DRM_SCANOUTPOS_VALID        (1 << 0)
+#define DRM_SCANOUTPOS_IN_VBLANK    (1 << 1)
+#define DRM_SCANOUTPOS_ACCURATE     (1 << 2)
 #define USE_REAL_VBLANKSTART		(1 << 30)
 #define GET_DISTANCE_TO_VBLANKSTART	(1 << 31)
 

drivers/gpu/drm/drm_irq.c

···
 
 	vblank->linedur_ns  = linedur_ns;
 	vblank->framedur_ns = framedur_ns;
+	vblank->hwmode = *mode;
 
 	DRM_DEBUG("crtc %u: hwmode: htotal %d, vtotal %d, vdisplay %d\n",
 		  crtc->base.id, mode->crtc_htotal,
···
  *     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.
- * @mode: mode which defines the scanout timings
  *
  * Implements calculation of exact vblank timestamps from given drm_display_mode
  * timings and current video scanout position of a CRTC. This can be called from
···
  * returns as no operation if a doublescan or interlaced video mode is
  * active. Higher level code is expected to handle this.
  *
+ * This function can be used to implement the &drm_driver.get_vblank_timestamp
+ * directly, if the driver implements the &drm_driver.get_scanout_position hook.
+ *
+ * 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
···
 					   unsigned int pipe,
 					   int *max_error,
 					   struct timeval *vblank_time,
-					   bool in_vblank_irq,
-					   const struct drm_display_mode *mode)
+					   bool in_vblank_irq)
 {
 	struct timeval tv_etime;
 	ktime_t stime, etime;
-	unsigned int vbl_status;
+	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;
-	unsigned flags = in_vblank_irq ? DRM_CALLED_FROM_VBLIRQ : 0;
 
-	if (pipe >= dev->num_crtcs) {
+	if (!drm_core_check_feature(dev, DRIVER_MODESET))
+		return false;
+
+	crtc = drm_crtc_from_index(dev, pipe);
+
+	if (pipe >= dev->num_crtcs || !crtc) {
 		DRM_ERROR("Invalid crtc %u\n", pipe);
 		return false;
 	}
···
 		DRM_ERROR("Called from driver 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.
···
 		 * Get vertical and horizontal scanout position vpos, hpos,
 		 * and bounding timestamps stime, etime, pre/post query.
 		 */
-		vbl_status = dev->driver->get_scanout_position(dev, pipe, flags,
+		vbl_status = dev->driver->get_scanout_position(dev, pipe,
+							       in_vblank_irq,
 							       &vpos, &hpos,
 							       &stime, &etime,
 							       mode);
 
 		/* Return as no-op if scanout query unsupported or failed. */
-		if (!(vbl_status & DRM_SCANOUTPOS_VALID)) {
-			DRM_DEBUG("crtc %u : scanoutpos query failed [0x%x].\n",
-				  pipe, vbl_status);
+		if (!vbl_status) {
+			DRM_DEBUG("crtc %u : scanoutpos query failed.\n",
+				  pipe);
 			return false;
 		}
 
···
 	etime = ktime_sub_ns(etime, delta_ns);
 	*vblank_time = ktime_to_timeval(etime);
 
-	DRM_DEBUG_VBL("crtc %u : v 0x%x p(%d,%d)@ %ld.%ld -> %ld.%ld [e %d us, %d rep]\n",
-		      pipe, vbl_status, hpos, vpos,
+	DRM_DEBUG_VBL("crtc %u : v p(%d,%d)@ %ld.%ld -> %ld.%ld [e %d us, %d rep]\n",
+		      pipe, hpos, vpos,
 		      (long)tv_etime.tv_sec, (long)tv_etime.tv_usec,
 		      (long)vblank_time->tv_sec, (long)vblank_time->tv_usec,
 		      duration_ns/1000, i);

drivers/gpu/drm/i915/i915_irq.c

···
 	return (position + crtc->scanline_offset) % vtotal;
 }
 
-static int i915_get_crtc_scanoutpos(struct drm_device *dev, unsigned int pipe,
-				    unsigned int flags, 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 pipe,
+				     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 *intel_crtc = intel_get_crtc_for_pipe(dev_priv,
···
 	int position;
 	int vbl_start, vbl_end, hsync_start, htotal, vtotal;
 	bool in_vbl = true;
-	int ret = 0;
 	unsigned long irqflags;
 
 	if (WARN_ON(!mode->crtc_clock)) {
 		DRM_DEBUG_DRIVER("trying to get scanoutpos for disabled "
 				 "pipe %c\n", pipe_name(pipe));
-		return 0;
+		return false;
 	}
 
 	htotal = mode->crtc_htotal;
···
 		vbl_end /= 2;
 		vtotal /= 2;
 	}
-
-	ret |= DRM_SCANOUTPOS_VALID | DRM_SCANOUTPOS_ACCURATE;
 
 	/*
 	 * Lock uncore.lock, as we will do multiple timing critical raw
···
 		*hpos = position - (*vpos * htotal);
 	}
 
-	/* In vblank? */
-	if (in_vbl)
-		ret |= DRM_SCANOUTPOS_IN_VBLANK;
-
-	return ret;
+	return true;
 }
 
 int intel_get_crtc_scanline(struct intel_crtc *crtc)
···
 	spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags);
 
 	return position;
-}
-
-static bool i915_get_vblank_timestamp(struct drm_device *dev, unsigned int pipe,
-			      int *max_error,
-			      struct timeval *vblank_time,
-			      bool in_vblank_irq)
-{
-	struct drm_i915_private *dev_priv = to_i915(dev);
-	struct intel_crtc *crtc;
-
-	if (pipe >= INTEL_INFO(dev_priv)->num_pipes) {
-		DRM_ERROR("Invalid crtc %u\n", pipe);
-		return false;
-	}
-
-	/* Get drm_crtc to timestamp: */
-	crtc = intel_get_crtc_for_pipe(dev_priv, pipe);
-	if (crtc == NULL) {
-		DRM_ERROR("Invalid crtc %u\n", pipe);
-		return false;
-	}
-
-	if (!crtc->base.hwmode.crtc_clock) {
-		DRM_DEBUG_KMS("crtc %u is disabled\n", pipe);
-		return false;
-	}
-
-	/* Helper routine in DRM core does all the work: */
-	return drm_calc_vbltimestamp_from_scanoutpos(dev, pipe, max_error,
-						     vblank_time, in_vblank_irq,
-						     &crtc->base.hwmode);
 }
 
 static void ironlake_rps_change_irq_handler(struct drm_i915_private *dev_priv)
···
 
 	dev_priv->hotplug.hpd_storm_threshold = HPD_STORM_DEFAULT_THRESHOLD;
 
-	dev->driver->get_vblank_timestamp = i915_get_vblank_timestamp;
+	dev->driver->get_vblank_timestamp = drm_calc_vbltimestamp_from_scanoutpos;
 	dev->driver->get_scanout_position = i915_get_crtc_scanoutpos;
 
 	if (IS_CHERRYVIEW(dev_priv)) {

drivers/gpu/drm/msm/mdp/mdp5/mdp5_kms.c

···
 	return NULL;
 }
 
-static int mdp5_get_scanoutpos(struct drm_device *dev, unsigned int pipe,
-			       unsigned int flags, int *vpos, int *hpos,
-			       ktime_t *stime, ktime_t *etime,
-			       const struct drm_display_mode *mode)
+static bool mdp5_get_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)
 {
 	struct msm_drm_private *priv = dev->dev_private;
 	struct drm_crtc *crtc;
 	struct drm_encoder *encoder;
 	int line, vsw, vbp, vactive_start, vactive_end, vfp_end;
-	int ret = 0;
 
 	crtc = priv->crtcs[pipe];
 	if (!crtc) {
 		DRM_ERROR("Invalid crtc %d\n", pipe);
-		return 0;
+		return false;
 	}
 
 	encoder = get_encoder_from_crtc(crtc);
 	if (!encoder) {
 		DRM_ERROR("no encoder found for crtc %d\n", pipe);
-		return 0;
+		return false;
 	}
-
-	ret |= DRM_SCANOUTPOS_VALID | DRM_SCANOUTPOS_ACCURATE;
 
 	vsw = mode->crtc_vsync_end - mode->crtc_vsync_start;
 	vbp = mode->crtc_vtotal - mode->crtc_vsync_end;
···
 
 	if (line < vactive_start) {
 		line -= vactive_start;
-		ret |= DRM_SCANOUTPOS_IN_VBLANK;
 	} else if (line > vactive_end) {
 		line = line - vfp_end - vactive_start;
-		ret |= DRM_SCANOUTPOS_IN_VBLANK;
 	} else {
 		line -= vactive_start;
 	}
···
 	if (etime)
 		*etime = ktime_get();
 
-	return ret;
-}
-
-static bool mdp5_get_vblank_timestamp(struct drm_device *dev, unsigned int pipe,
-				      int *max_error,
-				      struct timeval *vblank_time,
-				      bool in_vblank_irq)
-{
-	struct msm_drm_private *priv = dev->dev_private;
-	struct drm_crtc *crtc;
-
-	if (pipe < 0 || pipe >= priv->num_crtcs) {
-		DRM_ERROR("Invalid crtc %d\n", pipe);
-		return false;
-	}
-
-	crtc = priv->crtcs[pipe];
-	if (!crtc) {
-		DRM_ERROR("Invalid crtc %d\n", pipe);
-		return false;
-	}
-
-	return drm_calc_vbltimestamp_from_scanoutpos(dev, pipe, max_error,
-						     vblank_time, in_vblank_irq,
-						     &crtc->mode);
+	return true;
 }
 
 static u32 mdp5_get_vblank_counter(struct drm_device *dev, unsigned int pipe)
···
 	dev->mode_config.max_width = 0xffff;
 	dev->mode_config.max_height = 0xffff;
 
-	dev->driver->get_vblank_timestamp = mdp5_get_vblank_timestamp;
+	dev->driver->get_vblank_timestamp = drm_calc_vbltimestamp_from_scanoutpos;
 	dev->driver->get_scanout_position = mdp5_get_scanoutpos;
 	dev->driver->get_vblank_counter = mdp5_get_vblank_counter;
 	dev->max_vblank_count = 0xffffffff;

drivers/gpu/drm/nouveau/nouveau_display.c

···
 	return line;
 }
 
-static int
+static bool
 nouveau_display_scanoutpos_head(struct drm_crtc *crtc, int *vpos, int *hpos,
 				ktime_t *stime, ktime_t *etime)
 {
···
 	};
 	struct nouveau_display *disp = nouveau_display(crtc->dev);
 	struct drm_vblank_crtc *vblank = &crtc->dev->vblank[drm_crtc_index(crtc)];
-	int ret, retry = 20;
+	int retry = 20;
+	bool ret = false;
 
 	do {
 		ret = nvif_mthd(&disp->disp, 0, &args, sizeof(args));
 		if (ret != 0)
-			return 0;
+			return false;
 
 		if (args.scan.vline) {
-			ret |= DRM_SCANOUTPOS_ACCURATE;
-			ret |= DRM_SCANOUTPOS_VALID;
+			ret = true;
 			break;
 		}
 
···
 	if (stime) *stime = ns_to_ktime(args.scan.time[0]);
 	if (etime) *etime = ns_to_ktime(args.scan.time[1]);
 
-	if (*vpos < 0)
-		ret |= DRM_SCANOUTPOS_IN_VBLANK;
 	return ret;
 }
 
-int
+bool
 nouveau_display_scanoutpos(struct drm_device *dev, unsigned int pipe,
-			   unsigned int flags, int *vpos, int *hpos,
+			   bool in_vblank_irq, int *vpos, int *hpos,
 			   ktime_t *stime, ktime_t *etime,
 			   const struct drm_display_mode *mode)
 {
···
 		if (nouveau_crtc(crtc)->index == pipe) {
 			return nouveau_display_scanoutpos_head(crtc, vpos, hpos,
 							       stime, etime);
-		}
-	}
-
-	return 0;
-}
-
-bool
-nouveau_display_vblstamp(struct drm_device *dev, unsigned int pipe,
-			 int *max_error, struct timeval *time, bool in_vblank_irq)
-{
-	struct drm_crtc *crtc;
-
-	list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
-		if (nouveau_crtc(crtc)->index == pipe) {
-			struct drm_display_mode *mode;
-			if (drm_drv_uses_atomic_modeset(dev))
-				mode = &crtc->state->adjusted_mode;
-			else
-				mode = &crtc->hwmode;
-			return drm_calc_vbltimestamp_from_scanoutpos(dev,
-					pipe, max_error, time, in_vblank_irq,
-					mode);
 		}
 	}
 

drivers/gpu/drm/nouveau/nouveau_display.h

···
 void nouveau_display_resume(struct drm_device *dev, bool runtime);
 int  nouveau_display_vblank_enable(struct drm_device *, unsigned int);
 void nouveau_display_vblank_disable(struct drm_device *, unsigned int);
-int  nouveau_display_scanoutpos(struct drm_device *, unsigned int,
-				unsigned int, int *, int *, ktime_t *,
-				ktime_t *, const struct drm_display_mode *);
-bool  nouveau_display_vblstamp(struct drm_device *, unsigned int, int *,
-			       struct timeval *, bool);
+bool  nouveau_display_scanoutpos(struct drm_device *, unsigned int,
+				 bool, int *, int *, ktime_t *,
+				 ktime_t *, const struct drm_display_mode *);
 
 int  nouveau_crtc_page_flip(struct drm_crtc *crtc, struct drm_framebuffer *fb,
 			    struct drm_pending_vblank_event *event,

drivers/gpu/drm/nouveau/nouveau_drm.c

···
 	.enable_vblank = nouveau_display_vblank_enable,
 	.disable_vblank = nouveau_display_vblank_disable,
 	.get_scanout_position = nouveau_display_scanoutpos,
-	.get_vblank_timestamp = nouveau_display_vblstamp,
+	.get_vblank_timestamp = drm_calc_vbltimestamp_from_scanoutpos,
 
 	.ioctls = nouveau_ioctls,
 	.num_ioctls = ARRAY_SIZE(nouveau_ioctls),

drivers/gpu/drm/radeon/radeon_drv.c

···
 u32 radeon_get_vblank_counter_kms(struct drm_device *dev, unsigned int pipe);
 int radeon_enable_vblank_kms(struct drm_device *dev, unsigned int pipe);
 void radeon_disable_vblank_kms(struct drm_device *dev, unsigned int pipe);
-bool radeon_get_vblank_timestamp_kms(struct drm_device *dev, unsigned int pipe,
-				     int *max_error,
-				     struct timeval *vblank_time,
-				     bool in_vblank_irq);
 void radeon_driver_irq_preinstall_kms(struct drm_device *dev);
 int radeon_driver_irq_postinstall_kms(struct drm_device *dev);
 void radeon_driver_irq_uninstall_kms(struct drm_device *dev);
···
 #endif
 };
 
+static bool
+radeon_get_crtc_scanout_position(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)
+{
+	return radeon_get_crtc_scanoutpos(dev, pipe, 0, vpos, hpos,
+					  stime, etime, mode);
+}
+
 static struct drm_driver kms_driver = {
 	.driver_features =
 	    DRIVER_USE_AGP |
···
 	.get_vblank_counter = radeon_get_vblank_counter_kms,
 	.enable_vblank = radeon_enable_vblank_kms,
 	.disable_vblank = radeon_disable_vblank_kms,
-	.get_vblank_timestamp = radeon_get_vblank_timestamp_kms,
-	.get_scanout_position = radeon_get_crtc_scanoutpos,
+	.get_vblank_timestamp = drm_calc_vbltimestamp_from_scanoutpos,
+	.get_scanout_position = radeon_get_crtc_scanout_position,
 	.irq_preinstall = radeon_driver_irq_preinstall_kms,
 	.irq_postinstall = radeon_driver_irq_postinstall_kms,
 	.irq_uninstall = radeon_driver_irq_uninstall_kms,

drivers/gpu/drm/radeon/radeon_kms.c

···
 	spin_unlock_irqrestore(&rdev->irq.lock, irqflags);
 }
 
-/**
- * radeon_get_vblank_timestamp_kms - get vblank timestamp
- *
- * @dev: drm dev pointer
- * @crtc: crtc to get the timestamp for
- * @max_error: max error
- * @vblank_time: time value
- * @flags: flags passed to the driver
- *
- * Gets the timestamp on the requested crtc based on the
- * scanout position.  (all asics).
- * Returns true on success, false on failure.
- */
-bool radeon_get_vblank_timestamp_kms(struct drm_device *dev, int crtc,
-				     int *max_error,
-				     struct timeval *vblank_time,
-				     bool in_vblank_irq)
-{
-	struct drm_crtc *drmcrtc;
-	struct radeon_device *rdev = dev->dev_private;
-
-	if (crtc < 0 || crtc >= dev->num_crtcs) {
-		DRM_ERROR("Invalid crtc %d\n", crtc);
-		return false;
-	}
-
-	/* Get associated drm_crtc: */
-	drmcrtc = &rdev->mode_info.crtcs[crtc]->base;
-	if (!drmcrtc)
-		return false;
-
-	/* Helper routine in DRM core does all the work: */
-	return drm_calc_vbltimestamp_from_scanoutpos(dev, crtc, max_error,
-						     vblank_time, in_vblank_irq,
-						     &drmcrtc->hwmode);
-}
-
 const struct drm_ioctl_desc radeon_ioctls_kms[] = {
 	DRM_IOCTL_DEF_DRV(RADEON_CP_INIT, drm_invalid_op, DRM_AUTH|DRM_MASTER|DRM_ROOT_ONLY),
 	DRM_IOCTL_DEF_DRV(RADEON_CP_START, drm_invalid_op, DRM_AUTH|DRM_MASTER|DRM_ROOT_ONLY),

drivers/gpu/drm/radeon/radeon_mode.h

···
 };
 
 /* Driver internal use only flags of radeon_get_crtc_scanoutpos() */
+#define DRM_SCANOUTPOS_VALID        (1 << 0)
+#define DRM_SCANOUTPOS_IN_VBLANK    (1 << 1)
+#define DRM_SCANOUTPOS_ACCURATE     (1 << 2)
 #define USE_REAL_VBLANKSTART 		(1 << 30)
 #define GET_DISTANCE_TO_VBLANKSTART	(1 << 31)
 

drivers/gpu/drm/vc4/vc4_crtc.c

···
 }
 #endif
 
-int vc4_crtc_get_scanoutpos(struct drm_device *dev, unsigned int crtc_id,
-			    unsigned int flags, int *vpos, int *hpos,
-			    ktime_t *stime, ktime_t *etime,
-			    const struct drm_display_mode *mode)
+bool vc4_crtc_get_scanoutpos(struct drm_device *dev, unsigned int crtc_id,
+			     bool in_vblank_irq, int *vpos, int *hpos,
+			     ktime_t *stime, ktime_t *etime,
+			     const struct drm_display_mode *mode)
 {
 	struct vc4_dev *vc4 = to_vc4_dev(dev);
 	struct drm_crtc *crtc = drm_crtc_from_index(dev, crtc_id);
···
 	u32 val;
 	int fifo_lines;
 	int vblank_lines;
-	int ret = 0;
+	bool ret = false;
 
 	/* preempt_disable_rt() should go right here in PREEMPT_RT patchset. */
 
···
 	fifo_lines = vc4_crtc->cob_size / mode->crtc_hdisplay;
 
 	if (fifo_lines > 0)
-		ret |= DRM_SCANOUTPOS_VALID;
+		ret = true;
 
 	/* HVS more than fifo_lines into frame for compositing? */
 	if (*vpos > fifo_lines) {
···
 		 */
 		*vpos -= fifo_lines + 1;
 
-		ret |= DRM_SCANOUTPOS_ACCURATE;
 		return ret;
 	}
 
···
 	 * We can't get meaningful readings wrt. scanline position of the PV
 	 * and need to make things up in a approximative but consistent way.
 	 */
-	ret |= DRM_SCANOUTPOS_IN_VBLANK;
 	vblank_lines = mode->vtotal - mode->vdisplay;
 
-	if (flags & DRM_CALLED_FROM_VBLIRQ) {
+	if (in_vblank_irq) {
 		/*
 		 * Assume the irq handler got called close to first
 		 * line of vblank, so PV has about a full vblank
···
 		 * we are at the very beginning of vblank, as the hvs just
 		 * started refilling, and the stime and etime timestamps
 		 * truly correspond to start of vblank.
+		 *
+		 * Unfortunately there's no way to report this to upper levels
+		 * and make it more useful.
 		 */
-		if ((val & SCALER_DISPSTATX_FULL) != SCALER_DISPSTATX_FULL)
-			ret |= DRM_SCANOUTPOS_ACCURATE;
 	} else {
 		/*
 		 * No clue where we are inside vblank. Return a vpos of zero,
···
 	}
 
 	return ret;
-}
-
-bool vc4_crtc_get_vblank_timestamp(struct drm_device *dev, unsigned int crtc_id,
-				  int *max_error, struct timeval *vblank_time,
-				  bool in_vblank_irq)
-{
-	struct drm_crtc *crtc = drm_crtc_from_index(dev, crtc_id);
-	struct drm_crtc_state *state = crtc->state;
-
-	/* Helper routine in DRM core does all the work: */
-	return drm_calc_vbltimestamp_from_scanoutpos(dev, crtc_id, max_error,
-						     vblank_time, in_vblank_irq,
-						     &state->adjusted_mode);
 }
 
 static void vc4_crtc_destroy(struct drm_crtc *crtc)

drivers/gpu/drm/vc4/vc4_drv.c

···
 	.irq_uninstall = vc4_irq_uninstall,
 
 	.get_scanout_position = vc4_crtc_get_scanoutpos,
-	.get_vblank_timestamp = vc4_crtc_get_vblank_timestamp,
+	.get_vblank_timestamp = drm_calc_vbltimestamp_from_scanoutpos,
 
 #if defined(CONFIG_DEBUG_FS)
 	.debugfs_init = vc4_debugfs_init,

drivers/gpu/drm/vc4/vc4_drv.h

···
 extern struct platform_driver vc4_crtc_driver;
 bool vc4_event_pending(struct drm_crtc *crtc);
 int vc4_crtc_debugfs_regs(struct seq_file *m, void *arg);
-int vc4_crtc_get_scanoutpos(struct drm_device *dev, unsigned int crtc_id,
-			    unsigned int flags, int *vpos, int *hpos,
-			    ktime_t *stime, ktime_t *etime,
-			    const struct drm_display_mode *mode);
-bool vc4_crtc_get_vblank_timestamp(struct drm_device *dev, unsigned int crtc_id,
-				  int *max_error, struct timeval *vblank_time,
-				  bool in_vblank_irq);
+bool vc4_crtc_get_scanoutpos(struct drm_device *dev, unsigned int crtc_id,
+			     bool in_vblank_irq, int *vpos, int *hpos,
+			     ktime_t *stime, ktime_t *etime,
+			     const struct drm_display_mode *mode);
 
 /* vc4_debugfs.c */
 int vc4_debugfs_init(struct drm_minor *minor);

include/drm/drmP.h

···
 #define DRM_IF_VERSION(maj, min) (maj << 16 | min)
 
 
-/* Flags and return codes for get_vblank_timestamp() driver function. */
-#define DRM_CALLED_FROM_VBLIRQ 1
-
-/* get_scanout_position() return flags */
-#define DRM_SCANOUTPOS_VALID        (1 << 0)
-#define DRM_SCANOUTPOS_IN_VBLANK    (1 << 1)
-#define DRM_SCANOUTPOS_ACCURATE     (1 << 2)
-
 /**
  * DRM device structure. This structure represent a complete card that
  * may contain multiple heads.

include/drm/drm_drv.h

···
 	 *
 	 * Returns:
 	 *
-	 * Flags, or'ed together as follows:
-	 *
-	 * DRM_SCANOUTPOS_VALID:
-	 *     Query successful.
-	 * DRM_SCANOUTPOS_INVBL:
-	 *     Inside vblank.
-	 * DRM_SCANOUTPOS_ACCURATE: Returned position is accurate. A lack of
-	 *     this flag means that returned position may be offset by a
-	 *     constant but unknown small number of scanlines wrt. real scanout
-	 *     position.
+	 * True on success, false if a reliable scanout position counter could
+	 * not be read out.
 	 *
 	 * FIXME:
 	 *
···
 	 * move it to &struct drm_crtc_helper_funcs, like all the other
 	 * helper-internal hooks.
 	 */
-	int (*get_scanout_position) (struct drm_device *dev, unsigned int pipe,
-				     unsigned int flags, int *vpos, int *hpos,
-				     ktime_t *stime, ktime_t *etime,
-				     const struct drm_display_mode *mode);
+	bool (*get_scanout_position) (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);
 
 	/**
 	 * @get_vblank_timestamp:

include/drm/drm_irq.h

···
 	 * drm_calc_timestamping_constants().
 	 */
 	int linedur_ns;
+
+	/**
+	 * @hwmode:
+	 *
+	 * 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,
+	 * because that one is really hard to get from interrupt context.
+	 */
+	struct drm_display_mode hwmode;
+
 	/**
 	 * @enabled: Tracks the enabling state of the corresponding &drm_crtc to
 	 * avoid double-disabling and hence corrupting saved state. Needed by
···
 bool drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev,
 					   unsigned int pipe, int *max_error,
 					   struct timeval *vblank_time,
-					   bool in_vblank_irq,
-					   const struct drm_display_mode *mode);
+					   bool in_vblank_irq);
 void drm_calc_timestamping_constants(struct drm_crtc *crtc,
 				     const struct drm_display_mode *mode);