[PATCH v2 09/23] coresight: trbe: Clear TRBSR status at stop sites

[Leo Yan]

TRBSR_EL1 records the status of the buffer that just stopped. Clearing
it in trbe_enable_hw() postpones cleanup until another run starts. If
AUX output cannot restart, for example when AUX space is exhausted,
that clear never executes. Clear the status in arm_trbe_disable()
after disabling TRBE instead.

trbe_handle_overflow() can start the next run without calling
arm_trbe_disable(). Clear the stopped buffer's syndrome and status bits
while TRBE is disabled, before attempting the AUX restart. This also
leaves the status clean when the restart fails.

Signed-off-by: Leo Yan <leo.yan at arm.com>
---
 drivers/hwtracing/coresight/coresight-trbe.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c
index 26e7554d6bdd31f8a55a8bc3a7b6d4c49b984b9b..dd9c9330bb0c739795f300dafc6ce34e72fbf280 100644
--- a/drivers/hwtracing/coresight/coresight-trbe.c
+++ b/drivers/hwtracing/coresight/coresight-trbe.c
@@ -655,7 +655,6 @@ static void trbe_enable_hw(struct trbe_buf *buf)
 	WARN_ON(buf->trbe_hw_base < buf->trbe_base);
 	WARN_ON(buf->trbe_write < buf->trbe_hw_base);
 	WARN_ON(buf->trbe_write >= buf->trbe_limit);
-	clr_trbe_status();
 	set_trbe_base_pointer(buf->trbe_hw_base);
 	set_trbe_write_pointer(buf->trbe_write);
 
@@ -1069,6 +1068,8 @@ static int arm_trbe_disable(struct coresight_device *csdev)
 		return -EINVAL;
 
 	trbe_drain_and_disable_local(cpudata);
+	clr_trbe_status();
+
 	buf->cpudata = NULL;
 	cpudata->buf = NULL;
 	cpudata->mode = CS_MODE_DISABLED;
@@ -1095,6 +1096,13 @@ static int trbe_handle_overflow(struct perf_output_handle *handle)
 	unsigned long size;
 	struct etm_event_data *event_data;
 
+	/*
+	 * Clear the status. No context synchronization is required here,
+	 * since context synchronization will be performed before TRBE is
+	 * re-enabled (see trbe_enable_hw()).
+	 */
+	clr_trbe_status();
+
 	size = trbe_get_trace_size(handle, buf, true);
 	if (buf->snapshot)
 		handle->head += size;

-- 
2.34.1