drm/i915/perf: move pollin setup to non hw specific code

This isn't really gen specific stuff, so just move it to the common
code.

v2: Rebase (Umesh)
v3: Remove comment, pollin is a per stream state already (Ashutosh)

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
Reviewed-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200324185457.14635-3-umesh.nerlige.ramappa@intel.com

drivers/gpu/drm/i915/i915_perf.c

@@ -1418,8 +1418,6 @@ static void gen7_init_oa_buffer(struct i915_perf_stream *stream)
 	 * memory...
 	 */
 	memset(stream->oa_buffer.vaddr, 0, OA_BUFFER_SIZE);
-
-	stream->pollin = false;
 }
 
 static void gen8_init_oa_buffer(struct i915_perf_stream *stream)
@@ -1474,8 +1472,6 @@ static void gen8_init_oa_buffer(struct i915_perf_stream *stream)
 	 * memory...
 	 */
 	memset(stream->oa_buffer.vaddr, 0, OA_BUFFER_SIZE);
-
-	stream->pollin = false;
 }
 
 static void gen12_init_oa_buffer(struct i915_perf_stream *stream)
@@ -1531,8 +1527,6 @@ static void gen12_init_oa_buffer(struct i915_perf_stream *stream)
 	 */
 	memset(stream->oa_buffer.vaddr, 0,
 	       stream->oa_buffer.vma->size);
-
-	stream->pollin = false;
 }
 
 static int alloc_oa_buffer(struct i915_perf_stream *stream)
@@ -2600,6 +2594,8 @@ static void gen12_oa_enable(struct i915_perf_stream *stream)
  */
 static void i915_oa_stream_enable(struct i915_perf_stream *stream)
 {
+	stream->pollin = false;
+
 	stream->perf->ops.oa_enable(stream);
 
 	if (stream->periodic)
@@ -3023,12 +3019,8 @@ static ssize_t i915_perf_read(struct file *file,
 	 * effectively ensures we back off until the next hrtimer callback
 	 * before reporting another EPOLLIN event.
 	 */
-	if (ret >= 0 || ret == -EAGAIN) {
-		/* Maybe make ->pollin per-stream state if we support multiple
-		 * concurrent streams in the future.
-		 */
+	if (ret >= 0 || ret == -EAGAIN)
 		stream->pollin = false;
-	}
 
 	return ret;
 }