From: Philippe Mathieu-Daudé <f4bug@amsat.org>

Avoid propagating the clock change when the clock does not change.

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200806123858.30058-4-f4bug@amsat.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 include/hw/clock.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/include/hw/clock.h b/include/hw/clock.h
index d85af45c967..9ecd78b2c30 100644
--- a/include/hw/clock.h
+++ b/include/hw/clock.h
@@ -165,8 +165,9 @@ void clock_propagate(Clock *clk);
  */
 static inline void clock_update(Clock *clk, uint64_t value)
 {
-    clock_set(clk, value);
-    clock_propagate(clk);
+    if (clock_set(clk, value)) {
+        clock_propagate(clk);
+    }
 }
 
 static inline void clock_update_hz(Clock *clk, unsigned hz)
-- 
2.20.1