From b400642c5e93863ec17ea15fcbd3efc81c299531 Mon Sep 17 00:00:00 2001 From: Wentao Guan Date: Fri, 18 Sep 2026 17:09:10 +0800 Subject: [PATCH] cpufreq/amd-pstate: Skip auto_sel write when it already matches the mode Since commit 9dfd13f80c85 ("cpufreq/amd-pstate: Toggle auto_sel in active mode on shared memory systems"), shmem_init_perf() programs AUTONOMOUS_SELECTION_ENABLE unconditionally, including in active mode. Platforms that exclusively support autonomous selection report this field as an Integer of 1, as required by the ACPI specification, instead of as a register descriptor. cppc_get_reg_val() reads such a field back successfully, but cppc_set_reg_val() rejects the write with -EOPNOTSUPP because the entry is not an ACPI_TYPE_BUFFER. shmem_init_perf() propagates that error, so every amd_pstate_epp_cpu_init() fails, cpufreq_register_driver() ends up with an empty policy list and returns -ENODEV, and amd-pstate refuses to load at all: amd_pstate: failed to set auto_sel, ret: -95 amd_pstate: Failed to initialize CPU 0: -95 ... amd_pstate: failed to register with return -19 Skip the write when the register already holds the value the requested mode needs. Active and guided mode are fixed on these platforms, which report auto_sel as 1, while passive mode still fails to load on a platform that cannot disable autonomous selection, exactly as it did before the offending commit. Fixes: 9dfd13f80c85 ("cpufreq/amd-pstate: Toggle auto_sel in active mode on shared memory systems") Cc: stable@vger.kernel.org Reviewed-by: K Prateek Nayak Tested-by: K Prateek Nayak Tested-by: LFRon Signed-off-by: Wentao Guan Link: https://lore.kernel.org/r/20260918090909.86544-1-guanwentao@uniontech.com Signed-off-by: Mario Limonciello --- drivers/cpufreq/amd-pstate.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c index 8b2eb72c3973..c93a4b765dff 100644 --- a/drivers/cpufreq/amd-pstate.c +++ b/drivers/cpufreq/amd-pstate.c @@ -609,8 +609,10 @@ static int shmem_init_perf(struct amd_cpudata *cpudata) return 0; } - ret = cppc_set_auto_sel(cpudata->cpu, - (cppc_state == AMD_PSTATE_PASSIVE) ? 0 : 1); + if ((cppc_state != AMD_PSTATE_PASSIVE) == auto_sel) + return 0; + + ret = cppc_set_auto_sel(cpudata->cpu, !auto_sel); if (ret) pr_warn("failed to set auto_sel, ret: %d\n", ret);