[PATCH v3 4/5] acpi: Use _OSC method to convey processor OSPM capabilities

[Michal Wilczynski <michal.wilczynski@xxxxxxxxx>]

Change acpi_early_processor_osc() to return value in case of the failure.
Make it more generic - previously it served only to execute workaround
for buggy BIOS in Skylake systems. Now it will walk through ACPI
namespace looking for processor objects and will convey OSPM processor
capabilities using _OSC method.

Prefer using _OSC method over deprecated _PDC in the acpi_bus_init(). In
case of the failure of the _OSC, try using  _PDC as a fallback.

Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Signed-off-by: Michal Wilczynski <michal.wilczynski@xxxxxxxxx>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
---
 drivers/acpi/acpi_processor.c | 23 +++++++++++++----------
 drivers/acpi/bus.c            | 13 +++++++++----
 drivers/acpi/internal.h       |  9 +--------
 3 files changed, 23 insertions(+), 22 deletions(-)

diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_processor.c
index 0de0b05b6f53..8965e01406e0 100644
--- a/drivers/acpi/acpi_processor.c
+++ b/drivers/acpi/acpi_processor.c
@@ -669,17 +669,20 @@ static acpi_status __init acpi_hwp_native_thermal_lvt_osc(acpi_handle handle,
 	return AE_OK;
 }
 
-void __init acpi_early_processor_osc(void)
+acpi_status __init acpi_early_processor_osc(void)
 {
-	if (boot_cpu_has(X86_FEATURE_HWP)) {
-		acpi_walk_namespace(ACPI_TYPE_PROCESSOR, ACPI_ROOT_OBJECT,
-				    ACPI_UINT32_MAX,
-				    acpi_hwp_native_thermal_lvt_osc,
-				    NULL, NULL, NULL);
-		acpi_get_devices(ACPI_PROCESSOR_DEVICE_HID,
-				 acpi_hwp_native_thermal_lvt_osc,
-				 NULL, NULL);
-	}
+	acpi_status status;
+
+	processor_dmi_check();
+
+	status = acpi_walk_namespace(ACPI_TYPE_PROCESSOR, ACPI_ROOT_OBJECT,
+				     ACPI_UINT32_MAX, acpi_processor_osc, NULL,
+				     NULL, NULL);
+	if (ACPI_FAILURE(status))
+		return status;
+
+	return acpi_get_devices(ACPI_PROCESSOR_DEVICE_HID, acpi_processor_osc,
+				NULL, NULL);
 }
 #endif
 
diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
index d161ff707de4..e8d1f645224f 100644
--- a/drivers/acpi/bus.c
+++ b/drivers/acpi/bus.c
@@ -1317,9 +1317,6 @@ static int __init acpi_bus_init(void)
 		goto error1;
 	}
 
-	/* Set capability bits for _OSC under processor scope */
-	acpi_early_processor_osc();
-
 	/*
 	 * _OSC method may exist in module level code,
 	 * so it must be run after ACPI_FULL_INITIALIZATION
@@ -1335,7 +1332,15 @@ static int __init acpi_bus_init(void)
 
 	acpi_sysfs_init();
 
-	acpi_early_processor_set_pdc();
+#ifdef CONFIG_ARCH_MIGHT_HAVE_ACPI_PDC
+	status = acpi_early_processor_osc();
+	if (ACPI_FAILURE(status)) {
+		pr_err("_OSC methods failed, trying _PDC\n");
+		acpi_early_processor_set_pdc();
+	} else {
+		pr_info("_OSC methods ran successfully\n");
+	}
+#endif
 
 	/*
 	 * Maybe EC region is required at bus_scan/acpi_get_devices. So it
diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
index f979a2f7077c..e7cc41313997 100644
--- a/drivers/acpi/internal.h
+++ b/drivers/acpi/internal.h
@@ -151,17 +151,10 @@ int acpi_wakeup_device_init(void);
    -------------------------------------------------------------------------- */
 #ifdef CONFIG_ARCH_MIGHT_HAVE_ACPI_PDC
 void acpi_early_processor_set_pdc(void);
+acpi_status acpi_early_processor_osc(void);
 
 void processor_dmi_check(void);
 bool processor_physically_present(acpi_handle handle);
-#else
-static inline void acpi_early_processor_set_pdc(void) {}
-#endif
-
-#ifdef CONFIG_X86
-void acpi_early_processor_osc(void);
-#else
-static inline void acpi_early_processor_osc(void) {}
 #endif
 
 /* --------------------------------------------------------------------------
-- 
2.41.0