linux-kernel - [PATCH] ACPI: CPPC: Don't require flexible address space if X86_FEATURE

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Date:   Fri, 15 Jul 2022 12:33:25 -0500
From:   Mario Limonciello <mario.limonciello@....com>
To:     <mario.limonciello@....com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        "Len Brown" <lenb@...nel.org>,
        Pierre Gondois <pierre.gondois@....com>,
        "Sudeep Holla" <sudeep.holla@....com>
CC:     <perry.yuan@....com>,
        Arek Ruśniak <arek.rusi@...il.com>,
        <linux-acpi@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH] ACPI: CPPC: Don't require flexible address space if X86_FEATURE_CPPC is supported

commit 0651ab90e4ad ("ACPI: CPPC: Check _OSC for flexible address space")
changed _CPC probing to require flexible address space to be negotiated
for CPPC to work.

However it was observed that this caused a regression for Arek's ROG
Zephyrus G15 GA503QM which previously CPPC worked, but now it stopped
working.

To avoid causing a regression waive this failure when the CPU is known
to support CPPC.

Cc: Pierre Gondois <pierre.gondois@....com>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=216248
Fixes: 0651ab90e4ad ("ACPI: CPPC: Check _OSC for flexible address space")
Reported-and-tested-by: Arek Ruśniak <arek.rusi@...il.com>
Signed-off-by: Mario Limonciello <mario.limonciello@....com>
---
 drivers/acpi/cppc_acpi.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
index 6ff1901d7d43..3c6d4ef87be0 100644
--- a/drivers/acpi/cppc_acpi.c
+++ b/drivers/acpi/cppc_acpi.c
@@ -782,7 +782,8 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr)
 
 					if (!osc_cpc_flexible_adr_space_confirmed) {
 						pr_debug("Flexible address space capability not supported\n");
-						goto out_free;
+						if (!cpc_supported_by_cpu())
+							goto out_free;
 					}
 
 					addr = ioremap(gas_t->address, gas_t->bit_width/8);
@@ -809,7 +810,8 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr)
 				}
 				if (!osc_cpc_flexible_adr_space_confirmed) {
 					pr_debug("Flexible address space capability not supported\n");
-					goto out_free;
+					if (!cpc_supported_by_cpu())
+						goto out_free;
 				}
 			} else {
 				if (gas_t->space_id != ACPI_ADR_SPACE_FIXED_HARDWARE || !cpc_ffh_supported()) {
-- 
2.34.1