Re: [PATCH 3/3] powercap, intel_rapl, Add ignore_max_time_window_check module parameter for broken BIOSes

[Seiichi Ikarashi <s.ikarashi@jp.fujitsu.com>]

On 2016-01-22 01:15, Prarit Bhargava wrote:
> Some systems erroneously set the maximum time window field of
> MSR_PKG_POWER_INFO register to 0.  This results in a user not being able
> to set the time windows for the package.  In some cases, however, RAPL
> will still continue to work with a small window (albeit through some
> trial and error).  This patch adds a ignore_max_time_window_check module
> parameter to avoid the maximum time window check in set_time_window().
> 
> [v2]: change name to max_time_window_check, fix (val == 0) check
> 
> Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
> Cc: Prarit Bhargava <prarit@redhat.com>
> Cc: Radivoje Jovanovic <radivoje.jovanovic@intel.com>
> Cc: Seiichi Ikarashi <s.ikarashi@jp.fujitsu.com>
> Cc: Mathias Krause <minipli@googlemail.com>
> Cc: Ajay Thomas <ajay.thomas.david.rajamanickam@intel.com>
> Signed-off-by: Prarit Bhargava <prarit@redhat.com>
> ---
>  drivers/powercap/intel_rapl.c |   18 +++++++++++++++---
>  1 file changed, 15 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/powercap/intel_rapl.c b/drivers/powercap/intel_rapl.c
> index 14753e5..939026d 100644
> --- a/drivers/powercap/intel_rapl.c
> +++ b/drivers/powercap/intel_rapl.c
> @@ -505,13 +505,24 @@ static int get_max_time_window(struct powercap_zone *power_zone, int id,
>  
>  	if (rapl_read_data_raw(rd, MAX_TIME_WINDOW, true, &val))
>  		ret = -EIO;
> -	else
> +	else {
>  		*data = val;
> -
> +		if (val == 0)
> +			pr_warn_once(FW_BUG "intel_rapl: Maximum Time Window is zero.  This is a BIOS bug that should be reported to your hardware or BIOS vendor.  The value of zero may prevent Intel RAPL from functioning properly.  Most bugs can be avoided by setting the ignore_max_window_check module parameter.\n");

                                                                                                                                                                                                                                                                                 The correct name is ignore_max_time_window_check here.

--
Seiichi