drm/i915: Hold RPM wakelock while initializing OA buffer

OA buffer initialization involves access to HW registers to set
the OA base, head and tail. Ensure device is awake while setting
these. With this, all oa.ops are covered under RPM and forcewake
wakelock.

Cc: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Signed-off-by: NSagar Arun Kamble <sagar.a.kamble@intel.com>
Reviewed-by: NLionel Landwerlin <lionel.g.landwerlin@intel.com>
Signed-off-by: NMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1498585181-23048-1-git-send-email-sagar.a.kamble@intel.com
Fixes: d7965152 ("drm/i915: Enable i915 perf stream for Haswell OA unit")
Cc: <stable@vger.kernel.org> # v4.11+

drivers/gpu/drm/i915/i915_perf.c

@@ -2067,10 +2067,6 @@ static int i915_oa_stream_init(struct i915_perf_stream *stream,
 			return ret;
 	}
 
-	ret = alloc_oa_buffer(dev_priv);
-	if (ret)
-		goto err_oa_buf_alloc;
-
 	/* PRM - observability performance counters:
 	 *
 	 *   OACONTROL, performance counter enable, note:
@@ -2086,6 +2082,10 @@ static int i915_oa_stream_init(struct i915_perf_stream *stream,
 	intel_runtime_pm_get(dev_priv);
 	intel_uncore_forcewake_get(dev_priv, FORCEWAKE_ALL);
 
+	ret = alloc_oa_buffer(dev_priv);
+	if (ret)
+		goto err_oa_buf_alloc;
+
 	ret = dev_priv->perf.oa.ops.enable_metric_set(dev_priv);
 	if (ret)
 		goto err_enable;
@@ -2097,11 +2097,11 @@ static int i915_oa_stream_init(struct i915_perf_stream *stream,
 	return 0;
 
 err_enable:
-	intel_uncore_forcewake_put(dev_priv, FORCEWAKE_ALL);
-	intel_runtime_pm_put(dev_priv);
 	free_oa_buffer(dev_priv);
 
 err_oa_buf_alloc:
+	intel_uncore_forcewake_put(dev_priv, FORCEWAKE_ALL);
+	intel_runtime_pm_put(dev_priv);
 	if (stream->ctx)
 		oa_put_render_ctx_id(stream);