linux-kernel - [PATCH: 1/1] ACPI: make evaluation of thermal trip points before temperature or vice versa dependant on new "temp_b4_trip" module parameter to support older AMD x86

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Date:	Sun, 8 Jul 2012 19:50:54 +0100
From:	Jason Vas Dias <jason.vas.dias@...il.com>
To:	linux-kernel@...r.kernel.org
Cc:	Andreas Herrmann <herrmann.der.user@...glemail.com>,
	Matthew Garrett <mjg@...hat.com>, Len Brown <lenb@...nel.org>,
	Comrade DOS <suloevdmitry@...il.com>
Subject: [PATCH: 1/1] ACPI: make evaluation of thermal trip points before
 temperature or vice versa dependant on new "temp_b4_trip" module parameter to
 support older AMD x86_64s

This patch adds a new acpi.thermal.temp_b4_trip = 1 settting, which
causes the temperature
to be set before evaluation of thermal trip points (the old default) ;
 this mode should
be selected automatically by DMI match if the system identifies as "HP
Compaq 6715b" .

Please consider applying a patch like that attached to fix the issue reported
in lkml thread "Re: PROBLEM: Performance drop" recently,  whereby
it was found that HP 6715b laptops ( which have 2.2Ghz dual-core  AMD
x86_64 k8 CPUs)
get stuck running the CPU at 800Khz and cannot switch frequency. I have verified
that this still the case with v3.4.4 tagged "stable" kernel.

diff --git a/drivers/acpi/thermal.c b/drivers/acpi/thermal.c
index 7dbebea..de2b164 100644
--- a/drivers/acpi/thermal.c
+++ b/drivers/acpi/thermal.c
@@ -96,6 +96,10 @@ static int psv;
 module_param(psv, int, 0644);
 MODULE_PARM_DESC(psv, "Disable or override all passive trip points.");

+static int temp_b4_trip;
+module_param(temp_b4_trip, int, 0);
+MODULE_PARM_DESC(temp_b4_trip, "Get the temperature before
initializing trip points.");
+
 static int acpi_thermal_add(struct acpi_device *device);
 static int acpi_thermal_remove(struct acpi_device *device, int type);
 static int acpi_thermal_resume(struct acpi_device *device);
@@ -941,27 +945,41 @@ static int acpi_thermal_get_info(struct
acpi_thermal *tz)
        if (!tz)
                return -EINVAL;

-       /* Get trip points [_CRT, _PSV, etc.] (required) */
-       result = acpi_thermal_get_trip_points(tz);
-       if (result)
+       if( temp_b4_trip )
+       { /* some CPUs, eg AMD K8 need temperature before trip points
can be obtained */
+           /* Get temperature [_TMP] (required) */
+           result = acpi_thermal_get_temperature(tz);
+           if (result)
                return result;
-
-       /* Get temperature [_TMP] (required) */
-       result = acpi_thermal_get_temperature(tz);
-       if (result)
+
+           /* Get trip points [_CRT, _PSV, etc.] (required) */
+           result = acpi_thermal_get_trip_points(tz);
+           if (result)
                return result;
-
+       }else
+       { /* newer x86_64s need trip points set before temperature
obtained */
+           /* Get trip points [_CRT, _PSV, etc.] (required) */
+           result = acpi_thermal_get_trip_points(tz);
+           if (result)
+               return result;
+
+           /* Get temperature [_TMP] (required) */
+           result = acpi_thermal_get_temperature(tz);
+           if (result)
+               return result;
+       }
+
        /* Set the cooling mode [_SCP] to active cooling (default) */
        result = acpi_thermal_set_cooling_mode(tz, ACPI_THERMAL_MODE_ACTIVE);
        if (!result)
                tz->flags.cooling_mode = 1;
-
+
        /* Get default polling frequency [_TZP] (optional) */
        if (tzp)
                tz->polling_frequency = tzp;
        else
                acpi_thermal_get_polling_frequency(tz);
-
+
        return 0;
 }

@@ -1110,6 +1128,14 @@ static int thermal_psv(const struct dmi_system_id *d) {
        return 0;
 }

+static int thermal_temp_b4_trip(const struct dmi_system_id *d) {
+
+       printk(KERN_NOTICE "ACPI: %s detected: : "
+                           "getting temperature before trip point
initialisation\n", d->ident);
+       temp_b4_trip = 1;
+       return 0;
+}
+
 static struct dmi_system_id thermal_dmi_table[] __initdata = {
        /*
         * Award BIOS on this AOpen makes thermal control almost worthless.
@@ -1147,6 +1173,14 @@ static struct dmi_system_id thermal_dmi_table[]
__initdata = {
                DMI_MATCH(DMI_BOARD_NAME, "7ZX"),
                },
        },
+       {
+        .callback = thermal_temp_b4_trip,
+        .ident = "HP 6715b laptop",
+        .matches = {
+                    DMI_MATCH(DMI_SYS_VENDOR, "Hewlett-Packard"),
+                    DMI_MATCH(DMI_PRODUCT_NAME, "HP Compaq 6715b"),
+               },
+       },
        {}
 };

Download attachment "acpi_thermal_HP6715b.patch" of type "application/octet-stream" (2911 bytes)