linux-kernel - [PATCH] thermal/intel_powerclamp: Don't report an error for AMD CPUs

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Date:   Sat, 15 Feb 2020 11:09:37 -0500
From:   Alexander Koskovich <zvnexus@...il.com>
To:     arjan@...ux.intel.com, jacob.jun.pan@...ux.intel.com
Cc:     zvnexus@...il.com, Alexander Koskovich <zvnexus@...look.com>,
        Zhang Rui <rui.zhang@...el.com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Amit Kucheria <amit.kucheria@...durent.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Luc Van Oostenryck <luc.vanoostenryck@...il.com>,
        Petr Mladek <pmladek@...e.com>,
        Thomas Gleixner <tglx@...utronix.de>, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] thermal/intel_powerclamp: Don't report an error for AMD CPUs

Resolves dmesg error "intel_powerclamp: CPU does not support MWAIT".

The error that is outputted in dmesg prior to this patch
is innacurate, AMD Ryzen CPUs do support MWAIT. We could
also add the AMD vendor to the MWAIT check, but even though
AMD CPUs do support MWAIT, they fail the C-state package
check so it's better just to bail out in the beginning.

Signed-off-by: Alexander Koskovich <zvnexus@...look.com>
---
 drivers/thermal/intel/intel_powerclamp.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/thermal/intel/intel_powerclamp.c b/drivers/thermal/intel/intel_powerclamp.c
index 53216dcbe173..3c5b25bfa596 100644
--- a/drivers/thermal/intel/intel_powerclamp.c
+++ b/drivers/thermal/intel/intel_powerclamp.c
@@ -650,6 +650,11 @@ static struct thermal_cooling_device_ops powerclamp_cooling_ops = {
 	.set_cur_state = powerclamp_set_cur_state,
 };
 
+static const struct x86_cpu_id amd_cpu[] = {
+	{ X86_VENDOR_AMD },
+	{},
+};
+
 static const struct x86_cpu_id __initconst intel_powerclamp_ids[] = {
 	{ X86_VENDOR_INTEL, X86_FAMILY_ANY, X86_MODEL_ANY, X86_FEATURE_MWAIT },
 	{}
@@ -659,6 +664,11 @@ MODULE_DEVICE_TABLE(x86cpu, intel_powerclamp_ids);
 static int __init powerclamp_probe(void)
 {
 
+	if (x86_match_cpu(amd_cpu)) {
+		pr_info("Intel PowerClamp does not support AMD CPUs\n");
+		return -ENODEV;
+	}
+
 	if (!x86_match_cpu(intel_powerclamp_ids)) {
 		pr_err("CPU does not support MWAIT\n");
 		return -ENODEV;
-- 
2.25.0