Date:   Sat, 17 Sep 2022 23:46:23 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Christian Marangi <ansuelsmth@...il.com>
CC:     Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...ainline.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Alexey Dobriyan <adobriyan@...il.com>,
        Takashi Iwai <tiwai@...e.de>,
        Christian Brauner <brauner@...nel.org>,
        Ranjani Sridharan <ranjani.sridharan@...ux.intel.com>,
        Marc Herbert <marc.herbert@...el.com>,
        James Smart <jsmart2021@...il.com>,
        Justin Tee <justin.tee@...adcom.com>,
        Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, linux-clk@...r.kernel.org
Subject: Re: [PATCH v5 2/5] dt-bindings: arm: msm: Convert kpss-acc driver Documentation to yaml



On 17 September 2022 22:44:00 GMT+03:00, Christian Marangi <ansuelsmth@...il.com> wrote:
>On Sat, Sep 17, 2022 at 08:57:44PM +0200, Christian Marangi wrote:
>> On Sat, Sep 17, 2022 at 04:45:21PM +0300, Dmitry Baryshkov wrote:
>> > On Sat, 17 Sept 2022 at 00:54, Christian Marangi <ansuelsmth@...il.com> wrote:
>> > >
>> > > On Fri, Sep 16, 2022 at 11:31:49PM +0300, Dmitry Baryshkov wrote:
>> > > > On Fri, 16 Sept 2022 at 23:27, Christian Marangi <ansuelsmth@...il.com> wrote:
>> > > > >
>> > > > > On Fri, Sep 16, 2022 at 11:22:17PM +0300, Dmitry Baryshkov wrote:
>> > > > > > On Fri, 16 Sept 2022 at 23:13, Christian Marangi <ansuelsmth@...il.com> wrote:
>> > > > > > >
>> > > > > > > On Fri, Sep 16, 2022 at 11:06:35PM +0300, Dmitry Baryshkov wrote:
>> > > > > > > > On Fri, 16 Sept 2022 at 22:43, Christian Marangi <ansuelsmth@...il.com> wrote:
>> > > > > > > > >
>> > > > > > > > > On Fri, Sep 16, 2022 at 02:17:15PM -0500, Rob Herring wrote:
>> > > > > > > > > > On Wed, Sep 14, 2022 at 04:22:53PM +0200, Christian Marangi wrote:
>> > > > > > > > > > > Convert kpss-acc driver Documentation to yaml.
>> > > > > > > > > > > The original Documentation was wrong all along. Fix it while we are
>> > > > > > > > > > > converting it.
>> > > > > > > > > > > The example was wrong as kpss-acc-v2 should only expose the regs but we
>> > > > > > > > > > > don't have any driver that expose additional clocks. The kpss-acc driver
>> > > > > > > > > > > is only specific to v1. For this exact reason, limit all the additional
>> > > > > > > > > > > bindings (clocks, clock-names, clock-output-names and #clock-cells) to
>> > > > > > > > > > > v1 and also flag that these bindings should NOT be used for v2.
>> > > > > > > > > >
>> > > > > > > > > > Odd that a clock controller has no clocks, but okay.
>> > > > > > > > > >
>> > > > > > > > >
>> > > > > > > > > As said in the commit v2 is only used for regs. v2 it's only used in
>> > > > > > > > > arch/arm/mach-qcom/platsmp.c to setup stuff cpu hotplug and bringup.
>> > > > > > > > >
>> > > > > > > > > Should we split the 2 driver? To me the acc naming seems to be just
>> > > > > > > > > recycled for v2 and it's not really a clk controller.
>> > > > > > > > >
>> > > > > > > > > So keeping v2 in arm/msm/qcom,kpss-acc-v2.yaml and v1 moved to clock?
>> > > > > > > >
>> > > > > > > > I suspect that qcom,kpss-acc-v2 is misnamed as the "clock-controller".
>> > > > > > > > According to msm-3.10, these regions are used by the Krait core
>> > > > > > > > regulators.
>> > > > > > > >
>> > > > > > >
>> > > > > > > Well we need to understand how to handle this... change the compatible
>> > > > > > > it's a nono for sure. In platsmp.c they are used for cpu power control
>> > > > > > > so could be that they are actually used to regulators. I would honestly
>> > > > > > > move v1 to clock and leave v2 to arm/msm but I'm not cetain on what name
>> > > > > > > to assign to the 2 yaml.
>> > > > > > >
>> > > > > > > What do you think?
>> > > > > >
>> > > > > > This is fine for me. If somebody gets better understanding of
>> > > > > > underlying hardware and works on actually using these blocks, he will
>> > > > > > update the bindings.
>> > > > > >
>> > > > > > My only suggestion would be to rename kpss-acc-v2 nodes to
>> > > > > > 'power-controller@...ress' and document them so.
>> > > > > >
>> > > > >
>> > > > > Ok so something like this?
>> > > > >
>> > > > >     power-controller@...88000 {
>> > > > >       compatible = "qcom,kpss-acc-v2";
>> > > > >       reg = <0xf9088000 0x1000>,
>> > > > >             <0xf9008000 0x1000>;
>> > > > >     };
>> > > > >
>> > > > > (and I will have to fix dtbs warning as they will be unmatched I think.)
>> > > > > Yaml naming:
>> > > > > qcom,kpss-acc-v1.yaml
>> > > > > qcom,kpss-acc-v2.yaml
>> > > > > Right?
>> > > >
>> > > > Sounds good to me.
>> > > >
>> > > > I'd even say clock/qcom,kpss-acc-v1.yaml and
>> > > > arm/msm/qcom,kpss-acc-v2.yaml or maybe power/qcom,kpss-acc-v2.yaml
>> > > >
>> > >
>> > > Wonder if the gcc driver should have the same tretement? It's also a
>> > > clock-controller driver that doesn't use clock at all... Do you have
>> > > some info about it?
>> > 
>> > As far as I understand, the kpss-gcc is a normal clock controller,
>> > isn't it? It provides clocks to other devices.
>> > 
>> 
>> Hi again... Having acc-v2 as power-controller would require to set
>> #power-domain-cells = <0>;

Why? I don't think so. Rob/Krzysztof, please correct me if I'm wrong.

>> 
>> Would that be acceptable? Considering it wouldn't expose any PM domain?
>> 
>> About kpss-gcc we have some device that for some reason doesn't have the
>> required clocks defined in the dts. I checked the related gcc and no PXO
>> defined and no pll8_vote clock defined. (the affected dts are all listed
>> in the related Documentation)
>> 
>> No idea how they currently work with the kpss-gcc driver as these
>> parents are missing. Guess the driver just fails to probe?
>> So this was the question if you had more info about it... since to me it
>> seems just another gcc v2 that doesn't expose clocks but it's just a
>> power-controller just like acc-v2. 
>> 
>> -- 
>> 	Ansuel
>
>(Also sorry for the double email)
>I'm checking the regs for apq8084 for example (from the dtsi)
>Are we really sure they are power-controller?

It looks like it's a regularor on steroids. See krait-regulator.c and corresponding bindings in msm-3.10/3.14. So I'd use either the regulator or the power-controller (with significant bias towards controller)

>Checking the regs it seems they just changed the location and they
>placed clock-controller and right after the power-controller.
>So one can get confused and say that 0xf9... can be all related to power
>controller. I posted the regs for reference.
>
>acc0 0xf9088000 0x1000
>saw0 0xf9089000 0x1000
>
>acc1 0xf9098000 0x1000
>saw1 0xf9099000 0x1000
>
>acc2 0xf90a8000 0x1000
>saw2 0xf90b9000 0x1000
>
>Anyway while at it there seems to be a bit of confusion about the naming
>here... We have on ipq8064 and ipq4019 the saw node set as regulator and
>with the regulator binding but on msm8974 and apq8084 the saw node set
>as power-controller (with the l2 node with the regulator binding).
>
>Think we should chose a name and fix every dts.
>So the main question here is...
>Should we keep acc as clock-controller or change it to power-controller
>(for v2)?
>
>Should we change saw node to regulator or power-controller?
>
>>From what I know acc are used to enable the cpu so it seems sane to keep
>them as clock-controller (even if v2 doesn't export clock)
>Saw node handle power (and in theory even low power state) so it seems
>sane to change them to power-controller.
>
>Currently we have no warning for saw node as they are not converted to
>yaml but as soon as someone convert the txt to yaml then we will have
>all sort of inconsistency so better take a decision now instead of
>convert saw to yaml and then change acc node again to fix them for good.


The saw is definitely a bigger thing than just a regularor (or a set of them). It is used to control pmics, it handles low-power states, so `power-controller'.

-- 
With best wishes
Dmitry

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