Re: [PATCH v3 2/2] dt-bindings: net: bluetooth: Add device tree bindings for QTI chip wcn3998

[Matthias Kaehlcke <mka@chromium.org>]

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.

> > > 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'?)

Thanks

Matthias