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

[Felix Held (Code Review)]

Felix Held has submitted this change. ( 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.

This was found by the scanbuild.

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

Change-Id: Ibdededdfd56287fb9b9223e78033a3cd6425e1a2
Signed-off-by: Werner Zeh 
Reviewed-on: https://review.coreboot.org/c/coreboot/+/69185
Tested-by: build bot (Jenkins) 
Reviewed-by: Marc Jones 
Reviewed-by: Angel Pons 
Reviewed-by: Eric Lai 
---
M src/soc/intel/common/block/power_limit/power_limit.c
1 file changed, 27 insertions(+), 3 deletions(-)

Approvals:
  build bot (Jenkins): Verified
  Marc Jones: Looks good to me, approved
  Angel Pons: Looks good to me, approved
  Eric Lai: Looks good to me, approved

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;