Mathew King has uploaded this change for review.
x86/tsc: Only call tsc_freq_mhz once to init clock
This change partially reverts
https://review.coreboot.org/c/coreboot/+/33928 by only calling
tsc_freq_mhz on timer init and storing the result.
The change caused an error on Drallion where coreboot could not
communicate with the TPM on a cold boot causing the system to not boot.
BUG=b:144002424
TEST=Repeatedly cold boot drallion without TPM errors
Change-Id: I8e9edafa3007568e8d27e3c19c9fd6fa7637786c
Signed-off-by: Mathew King <mathewk@chromium.org>
---
M src/cpu/x86/tsc/delay_tsc.c
1 file changed, 12 insertions(+), 3 deletions(-)
git pull ssh://review.coreboot.org:29418/coreboot refs/changes/64/36664/1
diff --git a/src/cpu/x86/tsc/delay_tsc.c b/src/cpu/x86/tsc/delay_tsc.c
index 7aa887a..dcec4fb 100644
--- a/src/cpu/x86/tsc/delay_tsc.c
+++ b/src/cpu/x86/tsc/delay_tsc.c
@@ -18,9 +18,18 @@
#include <delay.h>
#include <thread.h>
+static unsigned long clocks_per_usec CAR_GLOBAL;
+
void init_timer(void)
{
- (void)tsc_freq_mhz();
+ if (!car_get_var(clocks_per_usec))
+ car_set_var(clocks_per_usec, tsc_freq_mhz());
+}
+
+static inline unsigned long get_clocks_per_usec(void)
+{
+ init_timer();
+ return car_get_var(clocks_per_usec);
}
void udelay(unsigned int us)
@@ -34,7 +43,7 @@
start = rdtscll();
clocks = us;
- clocks *= tsc_freq_mhz();
+ clocks *= get_clocks_per_usec();
current = rdtscll();
while ((current - start) < clocks) {
cpu_relax();
@@ -72,7 +81,7 @@
current_tick = rdtscll();
ticks_elapsed = current_tick - mono_counter->last_value;
- ticks_per_usec = tsc_freq_mhz();
+ ticks_per_usec = get_clocks_per_usec();
/* Update current time and tick values only if a full tick occurred. */
if (ticks_elapsed >= ticks_per_usec) {
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