rk27xx: avoid one multiply in udelay() as pointed by kugel

Change-Id: Ie33a393b0d4c4b45975ca53ced91dd9f03369db1

1 files changed, 8 insertions, 1 deletions

diff --git a/firmware/target/arm/rk27xx/system-rk27xx.c b/firmware/target/arm/rk27xx/system-rk27xx.c
index a36b4e9581..77a2d120aa 100644
--- a/firmware/target/arm/rk27xx/system-rk27xx.c
+++ b/firmware/target/arm/rk27xx/system-rk27xx.c
@@ -177,9 +177,16 @@ int system_memory_guard(int newmode)
 /* usecs may be at most 2^32/200 (~21 seconds) for 200MHz max cpu freq */
 void udelay(unsigned usecs)
 {
+    unsigned cycles_per_usec;
     unsigned delay;
 
-    delay = (usecs * (cpu_frequency/1000000)) / 5;
+    if (cpu_frequency == CPUFREQ_MAX) {
+        cycles_per_usec = (CPUFREQ_MAX + 999999) / 1000000;
+    } else {
+        cycles_per_usec = (CPUFREQ_NORMAL + 999999) / 1000000;
+    }
+
+    delay = (usecs * cycles_per_usec) / 5;
 
     asm volatile(
         "1: subs %0, %0, #1  \n"    /* 1 cycle  */