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Date:   Tue, 26 Mar 2019 16:54:58 -0700
From:   Matthias Kaehlcke <mka@chromium.org>
To:     c-hbandi@codeaurora.org
Cc:     marcel@holtmann.org, johan.hedberg@gmail.com,
        linux-kernel@vger.kernel.org, linux-bluetooth@vger.kernel.org,
        hemantg@codeaurora.org, linux-arm-msm@vger.kernel.org,
        bgodavar@codeaurora.org, anubhavg@codeaurora.org,
        Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        devicetree@vger.kernel.org, linux-bluetooth-owner@vger.kernel.org
Subject: Re: [PATCH v3 2/2] dt-bindings: net: bluetooth: Add device tree
 bindings for QTI chip wcn3998
Message-ID: <20190326235458.GA112750@google.com>
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On Mon, Mar 25, 2019 at 05:00:31PM +0530, c-hbandi@codeaurora.org wrote:
> Hi Matthias,
> 
>  On 2019-03-15 00:26, Matthias Kaehlcke wrote:
> > Hi Harish,
> > 
> > On Wed, Mar 13, 2019 at 12:00:06PM +0530, c-hbandi@codeaurora.org wrote:
> > > Hi Matthias,
> > > 
> > > 
> > > On 2019-03-12 22:29, Matthias Kaehlcke wrote:
> > > > +DT folks
> > > >
> > > > Please add them in future versions (script/scripts/get_maintainer.pl
> > > > <patches> should have listed them)
> > > 
> > > [Harish] -- Will add them in new version of patches.
> > > >
> > > > On Tue, Mar 12, 2019 at 05:52:59PM +0530, Harish Bandi wrote:
> > > > > This patch enables regulators for the Qualcomm Bluetooth wcn3998
> > > > > controller.
> > > >
> > > > No, it doesn't.
> > > >
> > > > The next version should probably say something like "Add compatible
> > > > string for the Qualcomm WCN3998 Bluetooth controller.
> > > >
> > > [Harish] -- From new patch onwards will add all patch
> > > version changes and add proper description.
> > > 
> > > > Is there any particular reason why QCA drivers folks use 'wcn' instead
> > > > of 'WCN'? The QCA documentations calls it WCN399x, so I'd suggest to
> > > > consistently use the uppercase name in comments and documentation (and
> > > > log messages?).
> > > >
> > > [Harish] -- I think in DT we need to have small case like wcn,
> > 
> > agreed
> > 
> > > i think that is the reason it started using in code, comments and dt
> > > documentation.
> > 
> > AFAIK there are no hard rules for everything, my suggestion would be:
> > 
> > - use WCN399x
> >   - for general comments/documentation
> >   - commit messages
> >   - in DT context wcn3998-n seems ok
> > - use wcn399x
> >   - for function and variable names
> >   - for compatible strings
> > 
> > For logging: whatever, just be consistent.
> 
>  [Harish] --For Commit messages and all will try to follow change it new
> patch
> 
> > 
> > > > > Signed-off-by: Harish Bandi <c-hbandi@codeaurora.org>
> > > > > ---
> > > > > changes in v3:
> > > > > - updated to latest code base.
> > > >
> > > > This comment is useless, please describe what changed wrt the previous
> > > > version.
> > > [Harish] --  added details in v2, and v3 uploaded just to rebase on
> > > tip of
> > > bluetooth-next
> > > for better understanding of code in review. From new patch onwards
> > > will add
> > > all patch
> > > version changes and add proper description.
> > > >
> > > > > ---
> > > > >  .../devicetree/bindings/net/qualcomm-bluetooth.txt        | 15
> > > > > +++++++++++++++
> > > > >  1 file changed, 15 insertions(+)
> > > > >
> > > > > diff --git
> > > > > a/Documentation/devicetree/bindings/net/qualcomm-bluetooth.txt
> > > > > b/Documentation/devicetree/bindings/net/qualcomm-bluetooth.txt
> > > > > index 824c0e2..1221535 100644
> > > > > --- a/Documentation/devicetree/bindings/net/qualcomm-bluetooth.txt
> > > > > +++ b/Documentation/devicetree/bindings/net/qualcomm-bluetooth.txt
> > > > > @@ -53,3 +53,18 @@ serial@898000 {
> > > > >  		max-speed = <3200000>;
> > > > >  	};
> > > > >  };
> > > > > +
> > > > > +&blsp1_uart3 {
> > > > > +	pinctrl-names = "default";
> > > > > +	pinctrl-0 = <&blsp1_uart3_default>;
> > > > > +	status = "okay";
> > > > > +
> > > > > +	bluetooth: wcn3998-bt {
> > > > > +		compatible = "qcom,wcn3998-bt";
> > > > > +		vddio-supply = <&vreg_l6_1p8>;
> > > > > +		vddxo-supply = <&vreg_l5_1p8>;
> > > > > +		vddrf-supply = <&vreg_s5_1p35>;
> > > > > +		vddch0-supply = <&vdd_ch0_3p3>;
> > > > > +		max-speed = <3200000>;
> > > > > +	};
> > > > > +};
> > > > > \ No newline at end of file
> > > >
> > > > I think the example isn't really needed since it's essentially the
> > > > same as the one for 'qcom,wcn3990-bt'.
> > > >
> > > > But the important part is missing: add the new compatible string under
> > > > ´Required properties´. You also want to update the documentation that
> > > > mentiones 'qcom,wcn3990-bt' to 'qcom,wcn399x-bt' (assuming for now
> > > > that other possible WCN399x chips would be similar).
> > > >
> > > [Harish] -- Will check the DT properties, documentation and update
> > > accordingly in new patch.
> > > 
> > > > You mentioned in an earlier version of the series that there are
> > > > multiple WCN3998 variants with different requirements for
> > > > voltage/current. This seems to suggests that multiple compatible
> > > > strings are needed to distinguish between them.
> > > >
> > > [Harish] -- for now we want to add WCN3998 support only, What i mean
> > > to say
> > > in my earlier
> > > explanation that. WCN3990 is base variant and on top of that we have
> > > variants like WCN3990,
> > > WCN3998 and WCN3998-0,WCN3998-1 like that..
> > > So I think wcn399x would make sense for this series.
> > 
> > If the variants have relevant differences between them (like different
> > regulator requirements) I think you want unique names, rather than
> > 'wcn399x' (I was referring to comments/documentation with this
> > string).
> > 
> > If there are variants wouldn't your first 'wcn3998' already be a
> > 'wcn3998-n'? If 'wcn3998' without suffix is used I think it needs to
> > be valid for all 'wcn3998-n' variants (it might be less
> > power-efficient though than using the variant specific compatible
> > string), otherwise things get confusing (a 'wcn3998-2' isn't a
> > 'wcn3998'?)
> > 
> 
> 
>  [Harish] -- for now WCN3990 and WCN3998 only, also wcn3998-2 and wcn3998
> are same.
> So for now we are going to have only WCN3990 and WCN3998 for DT.

Since you brought up the different power requirements initially:

are your reasonably sure that future wcn3998-3, wcn3998-4, ... can
operate with the generic wcn3998 power settings?