linux-kernel - Re: [PATCH v2 0/6] arm64: dts: qcom: Fix broken regulator spec on RPMH boards

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Date:   Wed, 31 Aug 2022 14:00:18 -0500
From:   Andrew Halaney <ahalaney@...hat.com>
To:     Doug Anderson <dianders@...omium.org>
Cc:     Johan Hovold <johan@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Mark Brown <broonie@...nel.org>,
        Andy Gross <agross@...nel.org>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...ainline.org>,
        Bhupesh Sharma <bhupesh.sharma@...aro.org>,
        Johan Hovold <johan+linaro@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...ainline.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Vinod Koul <vkoul@...nel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 0/6] arm64: dts: qcom: Fix broken regulator spec on
 RPMH boards

On Wed, Aug 31, 2022 at 07:52:52AM -0700, Doug Anderson wrote:
> Hi,
>
> On Tue, Aug 30, 2022 at 11:47 PM Johan Hovold <johan@...nel.org> wrote:
> >
> > On Mon, Aug 29, 2022 at 09:49:46AM -0700, Douglas Anderson wrote:
> > > Prior to commit efb0cb50c427 ("regulator: qcom-rpmh: Implement
> > > get_optimum_mode(), not set_load()") several boards were able to
> > > change their regulator mode even though they had nothing listed in
> > > "regulator-allowed-modes". After that commit (and fixes [1]) we'll be
> > > stuck at the initial mode. Discussion of this (again, see [1]) has
> > > resulted in the decision that the old dts files were wrong and should
> > > be fixed to fully restore old functionality.
> > >
> > > This series attempts to fix everyone. I've kept each board in a
> > > separate patch to make stable / backports work easier.
> >
> > Should you also update the bindings so that this can be caught during
> > devicetree validation? That is, to always require
> > "regulator-allowed-modes" when "regulator-allow-set-load" is specified.
>
> Yeah, it's probably a good idea. I'm happy to review a patch that does
> that. I'm already quite a few patches deep of submitting random
> cleanups because someone mentioned it in a code review. ;-) That's
> actually how I got in this mess to begin with. The RPMH change was in
> response to a request in a different code review. ...and that came
> about in a code review that was posted in response to a comment about
> how awkward setting regulator loads was... Need to get back to my day
> job.

I can take a stab at this during the week here I hope.. I owe Doug for
the slew of patches and have wanted to peek at how all the dt-binding
validation stuff works anyways.

Thanks,
Andrew

>
> In any case, I think these dts patches are ready to land now.
>
>
> > Perhaps at least for RPMh as it seemed you found some cases were this
> > wasn't currently needed (even if that sounded like an Linux-specific
> > implementation detail).
>
> I think you're talking about the RPM vs. RPMH difference? It's
> actually not Linux specific. In RPM the API to the "hardware"
> (actually a remote processor) is to pass the load. In RPMH the API to
> the hardware is to pass a mode. This is why RPMH has
> "regulator-allowed-modes" and "regulator-initial-mode". Both RPM and
> RPMH have "regulator-allow-set-load" though...
>
> -Doug
>