coresight: trbe: Drop duplicate TRUNCATE flags

We mark the buffer as TRUNCATED when there is no space left
in the buffer. But we do it at different points.
    __trbe_normal_offset()
and also, at all the callers of the above function via
compute_trbe_buffer_limit(), when the limit == base (i.e
offset = 0 as returned by the __trbe_normal_offset()).

So, given that the callers already mark the buffer as TRUNCATED
drop the caller inside the __trbe_normal_offset().

This is in preparation to moving the handling of TRUNCATED
into a central place.

Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Leo Yan <leo.yan@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Link: https://lore.kernel.org/r/20210914102641.1852544-6-suzuki.poulose@arm.com
[Moved comment as Anshuman requested]
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>

drivers/hwtracing/coresight/coresight-trbe.c

@@ -252,13 +252,9 @@ static unsigned long __trbe_normal_offset(struct perf_output_handle *handle)
 	 * trbe_base				trbe_base + nr_pages
 	 *
 	 * Perf aux buffer does not have any space for the driver to write into.
-	 * Just communicate trace truncation event to the user space by marking
-	 * it with PERF_AUX_FLAG_TRUNCATED.
 	 */
-	if (!handle->size) {
-		perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED);
+	if (!handle->size)
 		return 0;
-	}
 
 	/* Compute the tail and wakeup indices now that we've aligned head */
 	tail = PERF_IDX2OFF(handle->head + handle->size, buf);
@@ -360,7 +356,6 @@ static unsigned long __trbe_normal_offset(struct perf_output_handle *handle)
 		return limit;
 
 	trbe_pad_buf(handle, handle->size);
-	perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED);
 	return 0;
 }
 
@@ -688,6 +683,11 @@ static void trbe_handle_spurious(struct perf_output_handle *handle)
 	buf->trbe_write = buf->trbe_base + PERF_IDX2OFF(handle->head, buf);
 	if (buf->trbe_limit == buf->trbe_base) {
 		trbe_drain_and_disable_local();
+		/*
+		 * Just communicate trace truncation event to the user space by
+		 * marking it with PERF_AUX_FLAG_TRUNCATED.
+		 */
+		perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED);
 		return;
 	}
 	trbe_enable_hw(buf);