[PATCH 1/2] acpi: cppc: add cpufreq device

Mian Yousaf Kaukab
2020-12-10T14:24:44Z

From: Mian Yousaf Kaukab <ykaukab@suse.de>

Since commit 28f06f770454 ("cppc_cpufreq: replace per-cpu structures with
lists"), cppc-cpufreq driver doesn't check availability of PSD data before
registering with cpufreq core. As a result on a ThunderX2 platform when
CPPC is disabled from BIOS, kernel log is spammed with following messages:

[ 180.974166] CPPC Cpufreq: Error in acquiring _CPC/_PSD data for CPUxx

acpi_cppc_processor_probe() never succeed in this case because
acpi_evaluate_object_typed("_CPC") always returns AE_NOT_FOUND. When
cpufreq core calls cppc_cpufreq_cpu_init(), driver fails to obtain PSD data
and print error messages.

Convert cppc-cpufreq driver to a platform driver (done in a separate patch)
and add cppc-cpufreq device when acpi_cppc_processor_probe() succeeds.

Fixes: 28f06f770454 ("cppc_cpufreq: replace per-cpu structures with lists")
Reported-by: Petr Cervinka <pcervinka@suse.com>
Signed-off-by: Mian Yousaf Kaukab <ykaukab@suse.de>
---
drivers/acpi/cppc_acpi.c | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)

diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
index 4e478f751ff7..adf9ca3be9fe 100644
--- a/drivers/acpi/cppc_acpi.c
+++ b/drivers/acpi/cppc_acpi.c
@@ -39,6 +39,7 @@
#include <linux/ktime.h>
#include <linux/rwsem.h>
#include <linux/wait.h>
+#include <linux/platform_device.h>

#include <acpi/cppc_acpi.h>

@@ -606,6 +607,23 @@ static bool is_cppc_supported(int revision, int num_ent)
return true;
}

+static void add_cppc_cpufreq_dev(void)
+{
+ static bool already_added;
+
+ if (!already_added) {
+ struct platform_device *pdev;
+
+ pdev = platform_device_register_simple("cppc-cpufreq", -1,
+ NULL, 0);
+ if (IS_ERR(pdev))
+ pr_err("Couldn't register cppc-cpufreq err=%ld\n",
+ PTR_ERR(pdev));
+ else
+ already_added = true;
+ }
+}
+
/*
* An example CPC table looks like the following.
*
@@ -815,6 +833,9 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr)
}

kfree(output.pointer);
+
+ add_cppc_cpufreq_dev();
+
return 0;

out_free:
--
2.26.2