linux-kernel - Re: [PATCH] powercap: intel_rapl: Don't warn about BIOS locked limits during resume

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Message-ID: <ZR22I-9YgGW9vADB@intel.com>
Date:   Wed, 4 Oct 2023 21:59:47 +0300
From:   Ville Syrjälä <ville.syrjala@...ux.intel.com>
To:     "Pandruvada, Srinivas" <srinivas.pandruvada@...el.com>
Cc:     "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        "Zhang, Rui" <rui.zhang@...el.com>,
        "Wysocki, Rafael J" <rafael.j.wysocki@...el.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "intel-gfx@...ts.freedesktop.org" <intel-gfx@...ts.freedesktop.org>,
        "Wang, Wendy" <wendy.wang@...el.com>
Subject: Re: [PATCH] powercap: intel_rapl: Don't warn about BIOS locked
 limits during resume

On Wed, Oct 04, 2023 at 06:45:22PM +0000, Pandruvada, Srinivas wrote:
> On Wed, 2023-10-04 at 21:34 +0300, Ville Syrjala wrote:
> > From: Ville Syrjälä <ville.syrjala@...ux.intel.com>
> > 
> > Restore enough of the original behaviour to stop spamming
> > dmesg with warnings about BIOS locked limits when trying
> > to restore them during resume.
> > 
> > This still doesn't 100% match the original behaviour
> > as we no longer attempt to blindly restore the BIOS locked
> > limits. No idea if that makes any difference in practice.
> > 
> I lost the context here. Why can't we simply change pr_warn to pr_debug
> here?

I presume someone wanted to make it pr_warn() for a reason.
I don't mind either way.

> 
> Thanks,
> Srinivas
> 
> > Cc: Zhang Rui <rui.zhang@...el.com>
> > Cc: Wang Wendy <wendy.wang@...el.com>
> > Cc: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> > Cc: Srinivas Pandruvada <srinivas.pandruvada@...el.com>
> > Fixes: 9050a9cd5e4c ("powercap: intel_rapl: Cleanup Power Limits
> > support")
> > Signed-off-by: Ville Syrjälä <ville.syrjala@...ux.intel.com>
> > ---
> >  drivers/powercap/intel_rapl_common.c | 28 ++++++++++++++++++++------
> > --
> >  1 file changed, 20 insertions(+), 8 deletions(-)
> > 
> > diff --git a/drivers/powercap/intel_rapl_common.c
> > b/drivers/powercap/intel_rapl_common.c
> > index 40a2cc649c79..9a6a40c83f82 100644
> > --- a/drivers/powercap/intel_rapl_common.c
> > +++ b/drivers/powercap/intel_rapl_common.c
> > @@ -882,22 +882,34 @@ static int rapl_read_pl_data(struct rapl_domain
> > *rd, int pl,
> >         return rapl_read_data_raw(rd, prim, xlate, data);
> >  }
> >  
> > -static int rapl_write_pl_data(struct rapl_domain *rd, int pl,
> > -                              enum pl_prims pl_prim,
> > -                              unsigned long long value)
> > +static int rapl_write_pl_data_nowarn(struct rapl_domain *rd, int pl,
> > +                                    enum pl_prims pl_prim,
> > +                                    unsigned long long value)
> >  {
> >         enum rapl_primitives prim = get_pl_prim(rd, pl, pl_prim);
> >  
> >         if (!is_pl_valid(rd, pl))
> >                 return -EINVAL;
> >  
> > -       if (rd->rpl[pl].locked) {
> > -               pr_warn("%s:%s:%s locked by BIOS\n", rd->rp->name,
> > rd->name, pl_names[pl]);
> > +       if (rd->rpl[pl].locked)
> >                 return -EACCES;
> > -       }
> >  
> >         return rapl_write_data_raw(rd, prim, value);
> >  }
> > +
> > +static int rapl_write_pl_data(struct rapl_domain *rd, int pl,
> > +                             enum pl_prims pl_prim,
> > +                             unsigned long long value)
> > +{
> > +       int ret;
> > +
> > +       ret = rapl_write_pl_data_nowarn(rd, pl, pl_prim, value);
> > +       if (ret == -EACCES)
> > +               pr_warn("%s:%s:%s locked by BIOS\n", rd->rp->name,
> > rd->name, pl_names[pl]);
> > +
> > +       return ret;
> > +}
> > +
> >  /*
> >   * Raw RAPL data stored in MSRs are in certain scales. We need to
> >   * convert them into standard units based on the units reported in
> > @@ -1634,8 +1646,8 @@ static void power_limit_state_restore(void)
> >                 rd = power_zone_to_rapl_domain(rp->power_zone);
> >                 for (i = POWER_LIMIT1; i < NR_POWER_LIMITS; i++)
> >                         if (rd->rpl[i].last_power_limit)
> > -                               rapl_write_pl_data(rd, i, PL_LIMIT,
> > -                                              rd-
> > >rpl[i].last_power_limit);
> > +                               rapl_write_pl_data_nowarn(rd, i,
> > PL_LIMIT,
> > +                                                         rd-
> > >rpl[i].last_power_limit);
> >         }
> >         cpus_read_unlock();
> >  }
> 

-- 
Ville Syrjälä
Intel