cpupower: Don't fetch maximum latency when EPP is enabled

JIRA: https://issues.redhat.com/browse/RHEL-80660

commit acf7126
Author: Mario Limonciello <[email protected]>
Date:   Wed Dec 18 13:09:55 2024 -0600

    cpupower: Don't fetch maximum latency when EPP is enabled

    When EPP has been enabled the hardware will autonomously change
    frequencies on it's own and thus there is no latency with changing
    from the kernel.

    Avoid doing the maximum latency check when EPP is found. This will
    apply to both amd-pstate and intel-pstate drivers.

    Link: https://lore.kernel.org/r/[email protected]
    Signed-off-by: Mario Limonciello <[email protected]>
    Signed-off-by: Shuah Khan <[email protected]>

Signed-off-by: David Arcari <[email protected]>

Author: darcari

tools/power/cpupower/utils/cpufreq-info.c

@@ -445,6 +445,9 @@ static int get_latency(unsigned int cpu, unsigned int human)
 {
 	unsigned long latency = cpufreq_get_transition_latency(cpu);
 
+	if (!get_epp(cpu, false))
+		return -EINVAL;
+
 	printf(_("  maximum transition latency: "));
 	if (!latency || latency == UINT_MAX) {
 		printf(_(" Cannot determine or is not supported.\n"));