linux-kernel - [Patch] acpi_power_meter: remove 'ignoring unsafe software power cap' message

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Message-ID: <TY2PR03MB3519C32A5BC640BA41356CBEDE000@TY2PR03MB3519.apcprd03.prod.outlook.com>
Date:   Fri, 7 Sep 2018 22:07:39 +0000
From:   Max Asbock <masbock@...ovo.com>
To:     "darrick.wong@...cle.com" <darrick.wong@...cle.com>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Chris McDermott" <lcm@...ovo.com>
Subject: [Patch] acpi_power_meter: remove 'ignoring unsafe software power cap'
 message

At boot time the acpi_power_meter driver greets users of non-IBM systems with the message: 

"Ignoring unsafe software power cap". 

This message is generally interpreted as meaning: The system is operating under an unsafe power  cap and Linux is ignoring this fact, thus living dangerously. It, or its presumed origin, has been blamed for system crashes. People spent time writing knowledge base articles which explain that the message doesn't mean what users think. I now have to write another such article telling people to ignore this message. To avoid future confusion and unnecessary work, I think the best solution is to remove the message. 

Here is my translation of the 'ignoring unsafe power cap' message:
'The acpi_power_meter driver discovered an ACPI object that would in theory allow software to set power caps. The driver could now create files in sysfs to expose this interface to user space, but it chooses not to do so'.

Patch: Remove error message because it is generally misinterpreted. A replacement
for the message is not necessary.

Signed-off-by: Max Asbock <masbock@...ovo.com>

diff --git a/drivers/hwmon/acpi_power_meter.c b/drivers/hwmon/acpi_power_meter.c
index 34e45b9..578e886 100644
--- a/drivers/hwmon/acpi_power_meter.c
+++ b/drivers/hwmon/acpi_power_meter.c
@@ -693,11 +693,8 @@ static int setup_attrs(struct acpi_power_meter_resource *resource)
 	}

 	if (resource->caps.flags & POWER_METER_CAN_CAP) {
-		if (!can_cap_in_hardware()) {
-			dev_err(&resource->acpi_dev->dev,
-				"Ignoring unsafe software power cap!\n");
+		if (!can_cap_in_hardware())
 			goto skip_unsafe_cap;
-		}

 		if (resource->caps.configurable_cap)
 			res = register_attrs(resource, rw_cap_attrs);