linux-kernel - Re: [PATCH v4 4/4] dt-bindings: net: broadcom-bluetooth: Add pcm config

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Message-ID: <20191114175836.GI27773@google.com>
Date:   Thu, 14 Nov 2019 09:58:36 -0800
From:   Matthias Kaehlcke <mka@...omium.org>
To:     Marcel Holtmann <marcel@...tmann.org>
Cc:     Abhishek Pandit-Subedi <abhishekpandit@...omium.org>,
        Johan Hedberg <johan.hedberg@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        linux-bluetooth@...r.kernel.org, dianders@...omium.org,
        devicetree@...r.kernel.org,
        "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, Ondrej Jirman <megous@...ous.com>,
        Mark Rutland <mark.rutland@....com>,
        Chen-Yu Tsai <wens@...e.org>
Subject: Re: [PATCH v4 4/4] dt-bindings: net: broadcom-bluetooth: Add pcm
 config

On Wed, Nov 13, 2019 at 01:21:06AM +0100, Marcel Holtmann wrote:
> Hi Abhishek,
> 
> > Add documentation for pcm parameters.
> > 
> > Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@...omium.org>
> > 
> > ---
> > 
> > Changes in v4:
> > - Fix incorrect function name in hci_bcm
> > 
> > Changes in v3:
> > - Change disallow baudrate setting to return -EBUSY if called before
> >  ready. bcm_proto is no longer modified and is back to being const.
> > - Changed btbcm_set_pcm_params to btbcm_set_pcm_int_params
> > - Changed brcm,sco-routing to brcm,bt-sco-routing
> > 
> > Changes in v2:
> > - Use match data to disallow baudrate setting
> > - Parse pcm parameters by name instead of as a byte string
> > - Fix prefix for dt-bindings commit
> > 
> > .../devicetree/bindings/net/broadcom-bluetooth.txt    | 11 +++++++++++
> > 1 file changed, 11 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/net/broadcom-bluetooth.txt b/Documentation/devicetree/bindings/net/broadcom-bluetooth.txt
> > index c749dc297624..42fb2fa8143d 100644
> > --- a/Documentation/devicetree/bindings/net/broadcom-bluetooth.txt
> > +++ b/Documentation/devicetree/bindings/net/broadcom-bluetooth.txt
> > @@ -29,6 +29,11 @@ Optional properties:
> >    - "lpo": external low power 32.768 kHz clock
> >  - vbat-supply: phandle to regulator supply for VBAT
> >  - vddio-supply: phandle to regulator supply for VDDIO
> > + - brcm,bt-sco-routing: 0-3 (PCM, Transport, Codec, I2S)
> > + - brcm,pcm-interface-rate: 0-4 (128KBps, 256KBps, 512KBps, 1024KBps, 2048KBps)
> > + - brcm,pcm-frame-type: 0-1 (short, long)
> > + - brcm,pcm-sync-mode: 0-1 (slave, master)
> > + - brcm,pcm-clock-mode: 0-1 (slave, master)
> 
> I think that all of them need to start with brcm,bt- prefix since it is rather Bluetooth specific.
> 
> > 
> > 
> > Example:
> > @@ -40,5 +45,11 @@ Example:
> >        bluetooth {
> >                compatible = "brcm,bcm43438-bt";
> >                max-speed = <921600>;
> > +
> > +               brcm,bt-sco-routing = [01];
> > +               brcm,pcm-interface-rate = [02];
> > +               brcm,pcm-frame-type = [00];
> > +               brcm,pcm-sync-mode = [01];
> > +               brcm,pcm-clock-mode = [01];
> >        };
> 
> My personal taste would be to add a comment after each entry that gives the human readable setting.

I'd suggest to define constants in include/dt-bindings/bluetooth/brcm.h
and use them instead of literals, with this we wouldn't rely on (optional)
comments to make the configuration human readable.