drm/i915/perf: remove redundant oa buffer initialization

We initialize the OA buffer everytime we enable the OA unit (first call in
gen[78]_oa_enable), so we don't need to initialize when preparing the metric
set.

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181023100707.31738-3-lionel.g.landwerlin@intel.com

drivers/gpu/drm/i915/i915_drv.h

@@ -1522,23 +1522,6 @@ struct i915_oa_ops {
 	 */
 	bool (*is_valid_flex_reg)(struct drm_i915_private *dev_priv, u32 addr);
 
-	/**
-	 * @init_oa_buffer: Resets the head and tail pointers of the
-	 * circular buffer for periodic OA reports.
-	 *
-	 * Called when first opening a stream for OA metrics, but also may be
-	 * called in response to an OA buffer overflow or other error
-	 * condition.
-	 *
-	 * Note it may be necessary to clear the full OA buffer here as part of
-	 * maintaining the invariable that new reports must be written to
-	 * zeroed memory for us to be able to reliable detect if an expected
-	 * report has not yet landed in memory.  (At least on Haswell the OA
-	 * buffer tail pointer is not synchronized with reports being visible
-	 * to the CPU)
-	 */
-	void (*init_oa_buffer)(struct drm_i915_private *dev_priv);
-
 	/**
 	 * @enable_metric_set: Selects and applies any MUX configuration to set
 	 * up the Boolean and Custom (B/C) counters that are part of the

drivers/gpu/drm/i915/i915_perf.c

@@ -1528,8 +1528,6 @@ static int alloc_oa_buffer(struct drm_i915_private *dev_priv)
 		goto err_unpin;
 	}
 
-	dev_priv->perf.oa.ops.init_oa_buffer(dev_priv);
-
 	DRM_DEBUG_DRIVER("OA Buffer initialized, gtt offset = 0x%x, vaddr = %p\n",
 			 i915_ggtt_offset(dev_priv->perf.oa.oa_buffer.vma),
 			 dev_priv->perf.oa.oa_buffer.vaddr);
@@ -1998,7 +1996,7 @@ static int i915_oa_stream_init(struct i915_perf_stream *stream,
 		return -EINVAL;
 	}
 
-	if (!dev_priv->perf.oa.ops.init_oa_buffer) {
+	if (!dev_priv->perf.oa.ops.enable_metric_set) {
 		DRM_DEBUG("OA unit not supported\n");
 		return -ENODEV;
 	}
@@ -3387,7 +3385,6 @@ void i915_perf_init(struct drm_i915_private *dev_priv)
 		dev_priv->perf.oa.ops.is_valid_mux_reg =
 			hsw_is_valid_mux_addr;
 		dev_priv->perf.oa.ops.is_valid_flex_reg = NULL;
-		dev_priv->perf.oa.ops.init_oa_buffer = gen7_init_oa_buffer;
 		dev_priv->perf.oa.ops.enable_metric_set = hsw_enable_metric_set;
 		dev_priv->perf.oa.ops.disable_metric_set = hsw_disable_metric_set;
 		dev_priv->perf.oa.ops.oa_enable = gen7_oa_enable;
@@ -3406,7 +3403,6 @@ void i915_perf_init(struct drm_i915_private *dev_priv)
 		 */
 		dev_priv->perf.oa.oa_formats = gen8_plus_oa_formats;
 
-		dev_priv->perf.oa.ops.init_oa_buffer = gen8_init_oa_buffer;
 		dev_priv->perf.oa.ops.oa_enable = gen8_oa_enable;
 		dev_priv->perf.oa.ops.oa_disable = gen8_oa_disable;
 		dev_priv->perf.oa.ops.read = gen8_oa_read;