linux-kernel - Re: [PATCH v7 3/7] arm64: dts: msm8996: thermal: Initialise via DT and add second controller

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Message-ID: <20180717235829.GF129942@google.com>
Date:   Tue, 17 Jul 2018 16:58:29 -0700
From:   Matthias Kaehlcke <mka@...omium.org>
To:     Doug Anderson <dianders@...omium.org>
Cc:     Amit Kucheria <amit.kucheria@...aro.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Rajendra Nayak <rnayak@...eaurora.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Eduardo Valentin <edubezval@...il.com>,
        smohanad@...eaurora.org,
        Vivek Gautam <vivek.gautam@...eaurora.org>,
        Andy Gross <andy.gross@...aro.org>,
        David Brown <david.brown@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        "open list:ARM/QUALCOMM SUPPORT" <linux-soc@...r.kernel.org>,
        devicetree@...r.kernel.org,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v7 3/7] arm64: dts: msm8996: thermal: Initialise via DT
 and add second controller

On Tue, Jul 17, 2018 at 04:55:10PM -0700, Doug Anderson wrote:
> Hi,
> 
> On Tue, Jul 17, 2018 at 4:42 PM, Matthias Kaehlcke <mka@...omium.org> wrote:
> > On Thu, Jul 12, 2018 at 02:09:04PM +0530, Amit Kucheria wrote:
> >> We also split up the regmap address space into two, for the TM and SROT
> >> registers. This was required to deal with different address offsets for the
> >> TM and SROT registers across different SoC families.
> >>
> >> 8996 has two TSENS IP blocks, initialise the second one too.
> >>
> >> Since tsens-common.c/init_common() currently only registers one address
> >> space, the order is important (TM before SROT). This is OK since the code
> >> doesn't really use the SROT functionality yet.
> >>
> >> Signed-off-by: Amit Kucheria <amit.kucheria@...aro.org>
> >> Reviewed-by: Bjorn Andersson <bjorn.andersson@...aro.org>
> >> Tested-by: Matthias Kaehlcke <mka@...omium.org>
> >> ---
> >>  arch/arm64/boot/dts/qcom/msm8996.dtsi | 14 ++++++++++++--
> >>  1 file changed, 12 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/arch/arm64/boot/dts/qcom/msm8996.dtsi b/arch/arm64/boot/dts/qcom/msm8996.dtsi
> >> index 8c7f9ca..688e752 100644
> >> --- a/arch/arm64/boot/dts/qcom/msm8996.dtsi
> >> +++ b/arch/arm64/boot/dts/qcom/msm8996.dtsi
> >> @@ -459,9 +459,19 @@
> >>                       status = "disabled";
> >>               };
> >>
> >> -             tsens0: thermal-sensor@...000 {
> >> +             tsens0: thermal-sensor@...000 {
> >                                        ~~~~~~
> >
> > I suppose the address of the TM block is used here instead of the SROT
> > address (which is lower) since SROT functionality is currently not
> > used. Would/should this change if/when the driver uses SROT?
> 
> For device tree you're always supposed to use the address of the first
> "reg" listed as the unit address in the node name.  It doesn't matter
> if it's bigger or smaller as long as it's the first one listed.
> 
> The bindings indicate that the TM block should be listed as the first
> register.  This won't change even if you start using SROT.

Thanks for the clarification, there is always something more to learn!

Reviewed-by: Matthias Kaehlcke <mka@...omium.org>