drm/vblank: Switch drm_driver->get_vblank_timestamp to return a bool

There's really no reason for anything more:
- Calling this while the crtc vblank stuff isn't set up is a driver
  bug. Those places alrready DRM_ERROR.
- Calling this when the crtc is off is either a driver bug (calling
  drm_crtc_handle_vblank at the wrong time) or a core bug (for
  anything else). Again, we DRM_ERROR.
- EINVAL is checked at higher levels already, and if we'd use struct
  drm_crtc * instead of (dev, pipe) it would be real obvious that
  those are again core bugs.

The only valid failure mode is crap hardware that couldn't sample a
useful timestamp, to ask the core to just grab a not-so-accurate
timestamp. Bool is perfectly fine for that.

v2: Also fix up the one caller, I lost that in the shuffling (Jani).

v3: Fixup commit message (Neil).

Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Mario Kleiner <mario.kleiner@tuebingen.mpg.de>
Cc: Eric Anholt <eric@anholt.net>
Cc: Rob Clark <robdclark@gmail.com>
Cc: linux-arm-msm@vger.kernel.org
Cc: freedreno@lists.freedesktop.org
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Ben Skeggs <bskeggs@redhat.com>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Acked-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170509140329.24114-1-daniel.vetter@ffwll.ch

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

@@ -1910,7 +1910,7 @@ int amdgpu_device_resume(struct drm_device *dev, bool resume, bool fbcon);
 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);
-int amdgpu_get_vblank_timestamp_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,
 				     unsigned flags);

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

@@ -945,9 +945,9 @@ void amdgpu_disable_vblank_kms(struct drm_device *dev, unsigned int pipe)
  *
  * Gets the timestamp on the requested crtc based on the
  * scanout position.  (all asics).
- * Returns postive status flags on success, negative error on failure.
+ * Returns true on success, false on failure.
  */
-int amdgpu_get_vblank_timestamp_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,
 				     unsigned flags)
@@ -957,7 +957,7 @@ int amdgpu_get_vblank_timestamp_kms(struct drm_device *dev, unsigned int pipe,
 
 	if (pipe >= dev->num_crtcs) {
 		DRM_ERROR("Invalid crtc %u\n", pipe);
-		return -EINVAL;
+		return false;
 	}
 
 	/* Get associated drm_crtc: */
@@ -966,7 +966,7 @@ int amdgpu_get_vblank_timestamp_kms(struct drm_device *dev, unsigned int pipe,
 		/* 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 -EINVAL;
+		return false;
 	}
 
 	/* Helper routine in DRM core does all the work: */

drivers/gpu/drm/drm_irq.c

@@ -724,21 +724,11 @@ EXPORT_SYMBOL(drm_calc_timestamping_constants);
  * active. Higher level code is expected to handle this.
  *
  * Returns:
- * Negative value on error, failure or if not supported in current
- * video mode:
- *
- * -EINVAL    Invalid CRTC.
- * -EAGAIN    Temporary unavailable, e.g., called before initial modeset.
- * -ENOTSUPP  Function not supported in current display mode.
- * -EIO       Failed, e.g., due to failed scanout position query.
- *
- * Returns or'ed positive status flags on success:
- *
- * DRM_VBLANKTIME_SCANOUTPOS_METHOD - Signal this method used for timestamping.
- * DRM_VBLANKTIME_INVBL - Timestamp taken while scanout was in vblank interval.
  *
+ * Returns true on success, and false on failure, i.e. when no accurate
+ * timestamp could be acquired.
  */
-int drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev,
+bool drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev,
 					   unsigned int pipe,
 					   int *max_error,
 					   struct timeval *vblank_time,
@@ -748,19 +738,18 @@ int drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev,
 	struct timeval tv_etime;
 	ktime_t stime, etime;
 	unsigned int vbl_status;
-	int ret = DRM_VBLANKTIME_SCANOUTPOS_METHOD;
 	int vpos, hpos, i;
 	int delta_ns, duration_ns;
 
 	if (pipe >= dev->num_crtcs) {
 		DRM_ERROR("Invalid crtc %u\n", pipe);
-		return -EINVAL;
+		return false;
 	}
 
 	/* Scanout position query not supported? Should not happen. */
 	if (!dev->driver->get_scanout_position) {
 		DRM_ERROR("Called from driver w/o get_scanout_position()!?\n");
-		return -EIO;
+		return false;
 	}
 
 	/* If mode timing undefined, just return as no-op:
@@ -768,7 +757,7 @@ int drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev,
 	 */
 	if (mode->crtc_clock == 0) {
 		DRM_DEBUG("crtc %u: Noop due to uninitialized mode.\n", pipe);
-		return -EAGAIN;
+		return false;
 	}
 
 	/* Get current scanout position with system timestamp.
@@ -792,7 +781,7 @@ int drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev,
 		if (!(vbl_status & DRM_SCANOUTPOS_VALID)) {
 			DRM_DEBUG("crtc %u : scanoutpos query failed [0x%x].\n",
 				  pipe, vbl_status);
-			return -EIO;
+			return false;
 		}
 
 		/* Compute uncertainty in timestamp of scanout position query. */
@@ -836,7 +825,7 @@ int drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev,
 		      (long)vblank_time->tv_sec, (long)vblank_time->tv_usec,
 		      duration_ns/1000, i);
 
-	return ret;
+	return true;
 }
 EXPORT_SYMBOL(drm_calc_vbltimestamp_from_scanoutpos);
 
@@ -872,25 +861,23 @@ static bool
 drm_get_last_vbltimestamp(struct drm_device *dev, unsigned int pipe,
 			  struct timeval *tvblank, unsigned flags)
 {
-	int ret;
+	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 (dev->driver->get_vblank_timestamp && (max_error > 0))
 		ret = dev->driver->get_vblank_timestamp(dev, pipe, &max_error,
 							tvblank, flags);
-		if (ret > 0)
-			return true;
-	}
 
 	/* GPU high precision timestamp query unsupported or failed.
 	 * Return current monotonic/gettimeofday timestamp as best estimate.
 	 */
+	if (!ret)
 		*tvblank = get_drm_timestamp();
 
-	return false;
+	return ret;
 }
 
 /**

drivers/gpu/drm/i915/i915_irq.c

@@ -964,7 +964,7 @@ int intel_get_crtc_scanline(struct intel_crtc *crtc)
 	return position;
 }
 
-static int i915_get_vblank_timestamp(struct drm_device *dev, unsigned int pipe,
+static bool i915_get_vblank_timestamp(struct drm_device *dev, unsigned int pipe,
 			      int *max_error,
 			      struct timeval *vblank_time,
 			      unsigned flags)
@@ -974,19 +974,19 @@ static int i915_get_vblank_timestamp(struct drm_device *dev, unsigned int pipe,
 
 	if (pipe >= INTEL_INFO(dev_priv)->num_pipes) {
 		DRM_ERROR("Invalid crtc %u\n", pipe);
-		return -EINVAL;
+		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 -EINVAL;
+		return false;
 	}
 
 	if (!crtc->base.hwmode.crtc_clock) {
 		DRM_DEBUG_KMS("crtc %u is disabled\n", pipe);
-		return -EBUSY;
+		return false;
 	}
 
 	/* Helper routine in DRM core does all the work: */

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

@@ -592,7 +592,7 @@ static int mdp5_get_scanoutpos(struct drm_device *dev, unsigned int pipe,
 	return ret;
 }
 
-static int mdp5_get_vblank_timestamp(struct drm_device *dev, unsigned int pipe,
+static bool mdp5_get_vblank_timestamp(struct drm_device *dev, unsigned int pipe,
 				      int *max_error,
 				      struct timeval *vblank_time,
 				      unsigned flags)
@@ -602,13 +602,13 @@ static int mdp5_get_vblank_timestamp(struct drm_device *dev, unsigned int pipe,
 
 	if (pipe < 0 || pipe >= priv->num_crtcs) {
 		DRM_ERROR("Invalid crtc %d\n", pipe);
-		return -EINVAL;
+		return false;
 	}
 
 	crtc = priv->crtcs[pipe];
 	if (!crtc) {
 		DRM_ERROR("Invalid crtc %d\n", pipe);
-		return -EINVAL;
+		return false;
 	}
 
 	return drm_calc_vbltimestamp_from_scanoutpos(dev, pipe, max_error,

drivers/gpu/drm/nouveau/nouveau_display.c

@@ -156,7 +156,7 @@ nouveau_display_scanoutpos(struct drm_device *dev, unsigned int pipe,
 	return 0;
 }
 
-int
+bool
 nouveau_display_vblstamp(struct drm_device *dev, unsigned int pipe,
 			 int *max_error, struct timeval *time, unsigned flags)
 {
@@ -174,7 +174,7 @@ nouveau_display_vblstamp(struct drm_device *dev, unsigned int pipe,
 		}
 	}
 
-	return -EINVAL;
+	return false;
 }
 
 static void

drivers/gpu/drm/nouveau/nouveau_display.h

@@ -71,7 +71,7 @@ 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 *);
-int  nouveau_display_vblstamp(struct drm_device *, unsigned int, int *,
+bool  nouveau_display_vblstamp(struct drm_device *, unsigned int, int *,
 			       struct timeval *, unsigned);
 
 int  nouveau_crtc_page_flip(struct drm_crtc *crtc, struct drm_framebuffer *fb,

drivers/gpu/drm/radeon/radeon_drv.c

@@ -115,7 +115,7 @@ int radeon_resume_kms(struct drm_device *dev, bool resume, bool fbcon);
 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);
-int radeon_get_vblank_timestamp_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,
 				     unsigned flags);

drivers/gpu/drm/radeon/radeon_kms.c

@@ -869,9 +869,9 @@ void radeon_disable_vblank_kms(struct drm_device *dev, int crtc)
  *
  * Gets the timestamp on the requested crtc based on the
  * scanout position.  (all asics).
- * Returns postive status flags on success, negative error on failure.
+ * Returns true on success, false on failure.
  */
-int radeon_get_vblank_timestamp_kms(struct drm_device *dev, int crtc,
+bool radeon_get_vblank_timestamp_kms(struct drm_device *dev, int crtc,
 				     int *max_error,
 				     struct timeval *vblank_time,
 				     unsigned flags)
@@ -881,13 +881,13 @@ int radeon_get_vblank_timestamp_kms(struct drm_device *dev, int crtc,
 
 	if (crtc < 0 || crtc >= dev->num_crtcs) {
 		DRM_ERROR("Invalid crtc %d\n", crtc);
-		return -EINVAL;
+		return false;
 	}
 
 	/* Get associated drm_crtc: */
 	drmcrtc = &rdev->mode_info.crtcs[crtc]->base;
 	if (!drmcrtc)
-		return -EINVAL;
+		return false;
 
 	/* Helper routine in DRM core does all the work: */
 	return drm_calc_vbltimestamp_from_scanoutpos(dev, crtc, max_error,

drivers/gpu/drm/vc4/vc4_crtc.c

@@ -270,7 +270,7 @@ int vc4_crtc_get_scanoutpos(struct drm_device *dev, unsigned int crtc_id,
 	return ret;
 }
 
-int vc4_crtc_get_vblank_timestamp(struct drm_device *dev, unsigned int crtc_id,
+bool vc4_crtc_get_vblank_timestamp(struct drm_device *dev, unsigned int crtc_id,
 				  int *max_error, struct timeval *vblank_time,
 				  unsigned flags)
 {

drivers/gpu/drm/vc4/vc4_drv.h

@@ -493,7 +493,7 @@ 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);
-int vc4_crtc_get_vblank_timestamp(struct drm_device *dev, unsigned int crtc_id,
+bool vc4_crtc_get_vblank_timestamp(struct drm_device *dev, unsigned int crtc_id,
 				  int *max_error, struct timeval *vblank_time,
 				  unsigned flags);
 

include/drm/drmP.h

@@ -322,7 +322,6 @@ struct pci_controller;
 
 /* Flags and return codes for get_vblank_timestamp() driver function. */
 #define DRM_CALLED_FROM_VBLIRQ 1
-#define DRM_VBLANKTIME_SCANOUTPOS_METHOD (1 << 0)
 
 /* get_scanout_position() return flags */
 #define DRM_SCANOUTPOS_VALID        (1 << 0)

include/drm/drm_drv.h

@@ -316,11 +316,10 @@ struct drm_driver {
 	 *
 	 * Returns:
 	 *
-	 * Zero if timestamping isn't supported in current display mode or a
-	 * negative number on failure. A positive status code on success,
-	 * which describes how the vblank_time timestamp was computed.
+	 * True on success, false on failure, which means the core should
+	 * fallback to a simple timestamp taken in drm_crtc_handle_vblank().
 	 */
-	int (*get_vblank_timestamp) (struct drm_device *dev, unsigned int pipe,
+	bool (*get_vblank_timestamp) (struct drm_device *dev, unsigned int pipe,
 				     int *max_error,
 				     struct timeval *vblank_time,
 				     unsigned flags);

include/drm/drm_irq.h

@@ -153,7 +153,7 @@ void drm_crtc_vblank_on(struct drm_crtc *crtc);
 void drm_vblank_cleanup(struct drm_device *dev);
 u32 drm_accurate_vblank_count(struct drm_crtc *crtc);
 
-int drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev,
+bool drm_calc_vbltimestamp_from_scanoutpos(struct drm_device *dev,
 					   unsigned int pipe, int *max_error,
 					   struct timeval *vblank_time,
 					   unsigned flags,