[coreboot-gerrit] [S] Change in coreboot[master]: soc/intel/block/power_limit: Avoid MSR read if it is not needed

[Werner Zeh (Code Review)]

Werner Zeh has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/69185 )

Change subject: soc/intel/block/power_limit: Avoid MSR read if it is not needed
......................................................................

soc/intel/block/power_limit: Avoid MSR read if it is not needed

In function 'set_power_limits' there is a path to bail out early if the
Kconfig switch SOC_INTEL_DISABLE_POWER_LIMITS is selected. In this case
reading the MSR PLATFORM_INFO is useless and can be avoided. So read it
right before the value is needed.

In addition, fix an unnecessary line break to increase code readability.

Found-by: scanbuild

Change-Id: Ibdededdfd56287fb9b9223e78033a3cd6425e1a2
Signed-off-by: Werner Zeh 
---
M src/soc/intel/common/block/power_limit/power_limit.c
1 file changed, 22 insertions(+), 3 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/85/69185/1

diff --git a/src/soc/intel/common/block/power_limit/power_limit.c b/src/soc/intel/common/block/power_limit/power_limit.c
index dce174b..d7c9077 100644
--- a/src/soc/intel/common/block/power_limit/power_limit.c
+++ b/src/soc/intel/common/block/power_limit/power_limit.c
@@ -72,7 +72,7 @@
 void set_power_limits(u8 power_limit_1_time,
    	struct soc_power_limits_config *conf)
 {
-	msr_t msr = rdmsr(MSR_PLATFORM_INFO);
+	msr_t msr;
    msr_t limit;
    unsigned int power_unit;
    unsigned int tdp, min_power, max_power, max_time, tdp_pl2, tdp_pl1;
@@ -96,9 +96,9 @@
    }

if (power_limit_1_time >= ARRAY_SIZE(power_limit_time_sec_to_msr))
-		power_limit_1_time =
-			ARRAY_SIZE(power_limit_time_sec_to_msr) - 1;
+		power_limit_1_time = ARRAY_SIZE(power_limit_time_sec_to_msr) - 1;

+	msr = rdmsr(MSR_PLATFORM_INFO);
    if (!(msr.lo & PLATFORM_INFO_SET_TDP))
    	return;