Re: [PATCH 6/9] ASoC: dt-bindings: bcm2835-rpi: add onboard audio bindings

[Nicolas Saenz Julienne]

Hi Stefan, thanks for the review,

On Tue, 2018-10-16 at 17:56 +0200, Stefan Wahren wrote:
> Hi Nicolas,
> 
> Am 16.10.2018 um 17:02 schrieb Nicolas Saenz Julienne:
> > Adds a device tree binding file for Raspberry pi's Headphones and
> > HDMI
> > audio output devices.
> > 
> > Based on raspberry's downstream kernel implementation:
> > 

https://github.com/raspberrypi/linux/blob/rpi-4.14.y/arch/arm/boot/dts/bcm2708-rpi.dtsi
> > 
> > Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@xxxxxxx>
> > ---
> >  .../bindings/sound/brcm,bcm2835-audio.txt         | 15
> > +++++++++++++++
> >  1 file changed, 15 insertions(+)
> >  create mode 100644
> > Documentation/devicetree/bindings/sound/brcm,bcm2835-audio.txt
> > 
> > diff --git a/Documentation/devicetree/bindings/sound/brcm,bcm2835-
> > audio.txt b/Documentation/devicetree/bindings/sound/brcm,bcm2835-
> > audio.txt
> > new file mode 100644
> > index 000000000000..ee6fa085aaa9
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/sound/brcm,bcm2835-
> > audio.txt
> > @@ -0,0 +1,15 @@
> > +Broadcom BCM283x audio device
> > +
> > +Required properties:
> > +
> > +- compatible: Should be "brcm,bcm2835-audio"
> > +- brcm,pwm-channels: number of PWM channels, they are behind RPi's
> > Video Core
> > +		     IV, not actual Linux PWM devices.
> > +
> > +Example:
> > +
> > +audio: audio {
> > +	compatible = "brcm,bcm2835-audio";
> > +	brcm,pwm-channels = <8>;
> > +};
> > +
> 
> i apologize but it seems to me that the TODO mentioned in the cover
> letter isn't update to date anymore.
> 
> Phil Elwell posted an important bugfix for vchiq before [1], but only
> the driver part has been applied yet. After applying the DT changes
> i'm
> not sure if it still works.
> 
> AFAIK the audio driver uses VCHIQ as a software interface and the
> binding doesn't describe the real hardware.
> 
> Since the camera driver will be registered as a platform device [2],
> i
> prefer this way for the audio driver, too.
> 
> I'm actually working on this here [3] (currently only compile
> tested).
> 

Fair enough. I wasn't feeling too good about the bindings myself. I
only went with them because I saw something similar was happening
between "raspberrypi,bcm2835-power" and "raspberrypi,bcm2835-firmware". 
I'll be glad to review & test your patches whenever they are ready.

This makes commits 6 to 9 useless. Do you want me to send a v2? I can
throw in an extra change Takashi suggested and update the TODO file.

Regards,
Nicolas

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