A snapshot session captures trace data only when userspace receives a
signal and disables tracing. Before disabling, enable circle mode
instead of fill mode to avoid unnecessary interrupt handling.

Signed-off-by: Leo Yan <leo.yan@arm.com>
---
 drivers/hwtracing/coresight/coresight-trbe.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c
index 0551ea9b4f8286c156e3c9c7ac94e2ecd3b9dc3f..ee9993d518d2a41f0d709b7d0690b2dfe0bef2d9 100644
--- a/drivers/hwtracing/coresight/coresight-trbe.c
+++ b/drivers/hwtracing/coresight/coresight-trbe.c
@@ -635,6 +635,12 @@ static void set_trbe_limit_pointer_enabled(struct trbe_buf *buf)
 	trblimitr &= ~TRBLIMITR_EL1_TM_MASK;
 	trblimitr &= ~TRBLIMITR_EL1_LIMIT_MASK;
 
+	if (buf->snapshot) {
+		trblimitr |= FIELD_PREP(TRBLIMITR_EL1_FM_MASK, TRBLIMITR_EL1_FM_CBUF) |
+			     FIELD_PREP(TRBLIMITR_EL1_TM_MASK, TRBLIMITR_EL1_TM_IGNR);
+		goto enable_trace_buf;
+	}
+
 	if (!buf->trbe_count ||
 	    buf->trbe_write + buf->trbe_count == buf->trbe_limit) {
 		/*
@@ -669,6 +675,7 @@ static void set_trbe_limit_pointer_enabled(struct trbe_buf *buf)
 			     FIELD_PREP(TRBLIMITR_EL1_TM_MASK, TRBLIMITR_EL1_TM_STOP);
 	}
 
+enable_trace_buf:
 	trblimitr |= (addr & PAGE_MASK);
 	set_trbe_enabled(buf->cpudata, trblimitr);
 }

-- 
2.34.1