Change in coreboot[master]: soc/intel/elkhartlake: Fix CPU frequency if RAPL is disabled

[Werner Zeh (Code Review)]

Attention is currently required from: Patrick Rudolph.
Werner Zeh has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/58891 )

Change subject: soc/intel/elkhartlake: Fix CPU frequency if RAPL is disabled
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soc/intel/elkhartlake: Fix CPU frequency if RAPL is disabled

Set the CPU frequency to the maximum nun-turbo ratio if RAPL is not
enabled. In addition disable turbo mode and EIST to get a stable CPU
frequency under all circumstances to improve real-time performance.

Change-Id: I30d09df45d2cb46ccaa2c7797392f2d2f43814da
Signed-off-by: Werner Zeh 
---
M src/soc/intel/elkhartlake/cpu.c
1 file changed, 10 insertions(+), 2 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/91/58891/1

diff --git a/src/soc/intel/elkhartlake/cpu.c b/src/soc/intel/elkhartlake/cpu.c
index 0fcc61d..39eca81 100644
--- a/src/soc/intel/elkhartlake/cpu.c
+++ b/src/soc/intel/elkhartlake/cpu.c
@@ -78,8 +78,16 @@
    /* Set energy policy */
    set_energy_perf_bias(ENERGY_POLICY_NORMAL);

-	/* Enable Turbo */
-	enable_turbo();
+	/* Set Max Non-Turbo ratio if RAPL is disabled. */
+	if (CONFIG(INTEL_SKIP_SET_POWER_LIMITS)) {
+		cpu_set_p_state_to_max_non_turbo_ratio();
+		/* Disable speed step and turbo mode */
+		cpu_set_eist(false);
+		disable_turbo();
+	} else {
+		/* Enable Turbo */
+		enable_turbo();
+	}
 }

static void per_cpu_smm_trigger(void)