When enable the Arm CoreSight PMU event, the context for AUX ring buffer
is prepared in the structure perf_output_handle, and its field "head"
points the head of the AUX ring buffer and it is updated after filling
AUX trace data into buffer.

Current code uses an extra field etr_perf_buffer::head to maintain the
header for the AUX ring buffer, thus it's not necessary and it's better
to directly perf_output_handle::head.

This patch removes the header etr_perf_buffer::head and directly used
perf_output_handle::head as the header for AUX ring buffer.

Signed-off-by: Leo Yan <redacted>
---
  drivers/hwtracing/coresight/coresight-tmc-etr.c | 10 +++-------
  1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
index acdb59e0e661..b22823d67680 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c

@@ -32,7 +32,6 @@ struct etr_flat_buf {
   * @etr_buf		- Actual buffer used by the ETR
   * @pid			- The PID this etr_perf_buffer belongs to.
   * @snaphost		- Perf session mode
- * @head		- handle->head at the beginning of the session.
   * @nr_pages		- Number of pages in the ring buffer.
   * @pages		- Array of Pages in the ring buffer.
   */

@@ -41,7 +40,6 @@ struct etr_perf_buffer {
  	struct etr_buf		*etr_buf;
  	pid_t			pid;
  	bool			snapshot;
-	unsigned long		head;
  	int			nr_pages;
  	void			**pages;
  };

@@ -1437,16 +1435,16 @@ static void tmc_free_etr_buffer(void *config)
   * buffer to the perf ring buffer.
   */
  static void tmc_etr_sync_perf_buffer(struct etr_perf_buffer *etr_perf,
+				     unsigned long head,
  				     unsigned long src_offset,
  				     unsigned long to_copy)
  {
  	long bytes;
  	long pg_idx, pg_offset;
-	unsigned long head = etr_perf->head;
  	char **dst_pages, *src_buf;
  	struct etr_buf *etr_buf = etr_perf->etr_buf;
  
-	head = etr_perf->head;
+	head = PERF_IDX2OFF(head, etr_perf);
  	pg_idx = head >> PAGE_SHIFT;
  	pg_offset = head & (PAGE_SIZE - 1);
  	dst_pages = (char **)etr_perf->pages;

@@ -1553,7 +1551,7 @@ tmc_update_etr_buffer(struct coresight_device *csdev,
  	/* Insert barrier packets at the beginning, if there was an overflow */
  	if (lost)
  		tmc_etr_buf_insert_barrier_packet(etr_buf, offset);
-	tmc_etr_sync_perf_buffer(etr_perf, offset, size);
+	tmc_etr_sync_perf_buffer(etr_perf, handle->head, offset, size);
  
  	/*
  	 * In snapshot mode we simply increment the head by the number of byte

@@ -1605,8 +1603,6 @@ static int tmc_enable_etr_sink_perf(struct coresight_device *csdev, void *data)
  		goto unlock_out;
  	}
  
-	etr_perf->head = PERF_IDX2OFF(handle->head, etr_perf);
-
  	/*
  	 * No HW configuration is needed if the sink is already in
  	 * use for this session.