Re: [PATCH v3] cpufreq: intel_pstate: skip the driver if ACPI has power mgmt option

Linda Knippers
2013-11-06T06:25:48Z

Rafael J. Wysocki wrote:
> On Friday, November 01, 2013 09:29:48 AM Huang Adrian wrote:
>> Yes. HP BIOS has several power management modes (firmware, OS-control and
>> so on). For the OS control mode in HP BIOS, the Intel p-state driver will
>> be loaded. When the customer chooses the firmware power management in HP
>> BIOS, the Intel p-state driver will be ignored.
>>
>> I put hw_vendor_info vendor_info in case other vendors (Dell, Lenovo...)
>> have their firmware power management. Vendors should make sure their
>> firmware power management works properly, and they can go for adding their
>> vendor info to the variable.
>>
>> And, I have verified the patch on HP ProLiant servers. The patch worked
>> correctly.
>
> OK. I've added the above information to the patch changelog and fixed it up
> so that the driver builds for CONFIG_ACPI unset. The result is below, please
> retest.

As Adrian has recently left HP, I retested the updated patch on an HP ProLiant
server and verified that it is behaving correctly. When the BIOS is configured
for OS control for power management, the intel_pstate driver loads
as expected. When the BIOS is configured to provide the power management, the
intel_pstate driver does not load and we get the pcc_cpufreq driver instead.

Since Adrian is no longer with HP, please add:

Signed-off-by: Linda Knippers <linda.knippers@hp.com>

Thanks,

-- ljk

>
> Thanks,
> Rafael
>
>
> ---
> From: Adrian Huang <adrian.huang@hp.com>
> Subject: intel_pstate: skip the driver if ACPI has power mgmt option
>
> Do not load the Intel pstate driver if the platform firmware
> (ACPI BIOS) supports the power management alternatives.
> The ACPI BIOS indicates that the OS control mode can be used
> if the _PSS (Performance Supported States) is defined in ACPI
> table. For the OS control mode, the Intel pstate driver will be
> loaded.
>
> HP BIOS has several power management modes (firmware, OS-control and
> so on). For the OS control mode in HP BIOS, the Intel p-state driver
> will be loaded. When the customer chooses the firmware power
> management in HP BIOS, the Intel p-state driver will be ignored.
>
> I put hw_vendor_info vendor_info in case other vendors (Dell, Lenovo...)
> have their firmware power management. Vendors should make sure their
> firmware power management works properly, and they can go for adding
> their vendor info to the variable.
>
> I have verified the patch on HP ProLiant servers. The patch worked
> correctly.
>
> [rjw: Fixed up !CONFIG_ACPI build]
> Signed-off-by: Adrian Huang <adrian.huang@hp.com>
> ---
>
> drivers/cpufreq/intel_pstate.c | 74 +++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 74 insertions(+)
>
> Index: linux-pm/drivers/cpufreq/intel_pstate.c
> ===================================================================
> --- linux-pm.orig/drivers/cpufreq/intel_pstate.c
> +++ linux-pm/drivers/cpufreq/intel_pstate.c
> @@ -25,6 +25,7 @@
> #include <linux/types.h>
> #include <linux/fs.h>
> #include <linux/debugfs.h>
> +#include <linux/acpi.h>
> #include <trace/events/power.h>
>
> #include <asm/div64.h>
> @@ -777,6 +778,72 @@ static void copy_cpu_funcs(struct pstate
> pstate_funcs.set = funcs->set;
> }
>
> +#if IS_ENABLED(CONFIG_ACPI)
> +#include <acpi/processor.h>
> +
> +static bool intel_pstate_no_acpi_pss(void)
> +{
> + int i;
> +
> + for_each_possible_cpu(i) {
> + acpi_status status;
> + union acpi_object *pss;
> + struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
> + struct acpi_processor *pr = per_cpu(processors, i);
> +
> + if (!pr)
> + continue;
> +
> + status = acpi_evaluate_object(pr->handle, "_PSS", NULL, &buffer);
> + if (ACPI_FAILURE(status))
> + continue;
> +
> + pss = buffer.pointer;
> + if (pss && pss->type == ACPI_TYPE_PACKAGE) {
> + kfree(pss);
> + return false;
> + }
> +
> + kfree(pss);
> + }
> +
> + return true;
> +}
> +
> +struct hw_vendor_info {
> + u16 valid;
> + char oem_id[ACPI_OEM_ID_SIZE];
> + char oem_table_id[ACPI_OEM_TABLE_ID_SIZE];
> +};
> +
> +/* Hardware vendor-specific info that has its own power management modes */
> +static struct hw_vendor_info vendor_info[] = {
> + {1, "HP ", "ProLiant"},
> + {0, "", ""},
> +};
> +
> +static bool intel_pstate_platform_pwr_mgmt_exists(void)
> +{
> + struct acpi_table_header hdr;
> + struct hw_vendor_info *v_info;
> +
> + if (acpi_disabled
> + || ACPI_FAILURE(acpi_get_table_header(ACPI_SIG_FADT, 0, &hdr)))
> + return false;
> +
> + for (v_info = vendor_info; v_info->valid; v_info++) {
> + if (!strncmp(hdr.oem_id, v_info->oem_id, ACPI_OEM_ID_SIZE)
> + && !strncmp(hdr.oem_table_id, v_info->oem_table_id, ACPI_OEM_TABLE_ID_SIZE)
> + && intel_pstate_no_acpi_pss())
> + return true;
> + }
> +
> + return false;
> +}
> +#else /* CONFIG_ACPI not enabled */
> +static inline bool intel_pstate_platform_pwr_mgmt_exists(void) { return false; }
> +#endif /* CONFIG_ACPI */
> +
> static int __init intel_pstate_init(void)
> {
> int cpu, rc = 0;
> @@ -790,6 +857,13 @@ static int __init intel_pstate_init(void
> if (!id)
> return -ENODEV;
>
> + /*
> + * The Intel pstate driver will be ignored if the platform
> + * firmware has its own power management modes.
> + */
> + if (intel_pstate_platform_pwr_mgmt_exists())
> + return -ENODEV;
> +
> cpu_info = (struct cpu_defaults *)id->driver_data;
>
> copy_pid_params(&cpu_info->pid_policy);
>