linux-kernel - Re: [PATCH V2] ARM: dts: omap36xx: Remove turbo mode for 1GHz variants

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Date:   Thu, 7 Oct 2021 20:00:38 +0200
From:   Andreas Kemnade <andreas@...nade.info>
To:     Adam Ford <aford173@...il.com>
Cc:     "H. Nikolaus Schaller" <hns@...delico.com>,
        Linux-OMAP <linux-omap@...r.kernel.org>,
        Adam Ford-BE <aford@...conembedded.com>,
        Benoît Cousson <bcousson@...libre.com>,
        Tony Lindgren <tony@...mide.com>,
        Rob Herring <robh+dt@...nel.org>,
        devicetree <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V2] ARM: dts: omap36xx: Remove turbo mode for 1GHz
 variants

On Sat, 2 Oct 2021 07:12:05 -0500
Adam Ford <aford173@...il.com> wrote:

> On Fri, Oct 1, 2021 at 4:59 AM H. Nikolaus Schaller <hns@...delico.com> wrote:
> >
> >
> >  
> > > Am 01.10.2021 um 09:54 schrieb Andreas Kemnade <andreas@...nade.info>:
> > >
> > > On Sat,  9 Jan 2021 11:01:03 -0600
> > > Adam Ford <aford173@...il.com> wrote:
> > >  
> > >> Previously, the 1GHz variants were marked as a turbo,
> > >> because that variant has reduced thermal operating range.
> > >>
> > >> Now that the thermal throttling is in place, it should be
> > >> safe to remove the turbo-mode from the 1GHz variants, because
> > >> the CPU will automatically slow if the thermal limit is reached.
> > >>
> > >> Signed-off-by: Adam Ford <aford173@...il.com>
> > >> ---
> > >> V2:  The orignal patch had the wrong file added. Add the omap36xx.dtsi
> > >>  
> > > hmm, I somehow expected that there is a revert of this thing going
> > > through. But now, the turbo-mode is still missing  
> >
> > tagging by turbo-mode means the OPP is *disabled* by default and
> > needs to be enabled actively.
> >  
> > > and I understood the
> > > revert is only in Nikolaus' trees.  
> >
> > It is just a revert for the gta04a5 because I think it is the only board
> > which is affected (maybe it would need SmartReflex in operation to
> > fine tune the OPPs compared to the generic table). Therefore I have
> > a patch which adds turbo-mode to the gta04a5.dts
> >  
> > > The 1Ghz mode was working for some
> > > time but does not anymore. Is it just me or do others also have the
> > > same problems?  
> >
> > That would be interesting to know.
> >  
> 
> What version are you seeing the break?  It's working for me on 5.15.y branch
> 
> # cat /sys/devices/system/cpu/cpufreq/policy0/scaling_available_frequencies
> 300000 600000 800000 1000000
> # uname -a
> Linux buildroot 5.14.9-00260-g70248e7b378b-dirty #1 SMP Sat Oct 2
> 06:56:02 CDT 2021 armv7l GNU/Linux
> #
> 

I see this one: I remember there was also a discussion about proper
handling of that but I do not remember the final result:

Author: H. Nikolaus Schaller <hns@...delico.com>
Date:   Mon Dec 2 22:10:55 2019 +0100

    Revert "ARM: OMAP2+: Fix warnings with broken omap2_set_init_voltage()"
    
    This reverts commit cf395f7ddb9ebc6b2d28d83b53d18aa4e7c19701.
    
    This patch is in conflict with 1GHz OPP.




commit ae44b701fb6afb2be62defff590531e3b0632772
Author: H. Nikolaus Schaller <hns@...delico.com>
Date:   Sat Apr 10 16:59:53 2021 +0200

    ARM: DTS: gta04a5: disable 1GHz OPP again because it is not reliable
    
    To enable on a running system:
    
    echo 1 >/sys/devices/system/cpu/cpufreq/boost
    
    The symptom can be spurious hangs and virtual paging error,
    kernel panics and strange things.

on top of 5.13-rcX in Nikolaus trees.

Regards,
Andreas