cpufreq: amd-pstate: enable shared memory type CPPC by default

The amd-pstate-epp driver has been implemented and resolves the
performance drop issue seen in passive mode for shared memory type
CPPC systems. Users who enable the active mode driver will not
experience a performance drop compared to the passive mode driver.
Therefore, the EPP driver should be loaded by default for shared
memory type CPPC system to get better performance.

Signed-off-by: Perry Yuan <[email protected]>
Reviewed-by: Mario Limonciello <[email protected]>
Link: https://lore.kernel.org/r/c705507cf3ee790e544251cfd897ed11e8e57712.1718811234.git.perry.yuan@amd.com
Signed-off-by: Mario Limonciello <[email protected]>

Author: Perry Yuan

drivers/cpufreq/amd-pstate.c

@@ -86,15 +86,6 @@ struct quirk_entry {
 	u32 lowest_freq;
 };
 
-/*
- * TODO: We need more time to fine tune processors with shared memory solution
- * with community together.
- *
- * There are some performance drops on the CPU benchmarks which reports from
- * Suse. We are co-working with them to fine tune the shared memory solution. So
- * we disable it by default to go acpi-cpufreq on these processors and add a
- * module parameter to be able to enable it manually for debugging.
- */
 static struct cpufreq_driver *current_pstate_driver;
 static struct cpufreq_driver amd_pstate_driver;
 static struct cpufreq_driver amd_pstate_epp_driver;
@@ -1815,11 +1806,9 @@ static int __init amd_pstate_init(void)
 		/* Disable on the following configs by default:
 		 * 1. Undefined platforms
 		 * 2. Server platforms
-		 * 3. Shared memory designs
 		 */
 		if (amd_pstate_acpi_pm_profile_undefined() ||
-		    amd_pstate_acpi_pm_profile_server() ||
-		    !cpu_feature_enabled(X86_FEATURE_CPPC)) {
+		    amd_pstate_acpi_pm_profile_server()) {
 			pr_info("driver load is disabled, boot with specific mode to enable this\n");
 			return -ENODEV;
 		}