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

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@suse.de>
---
 .../bindings/sound/brcm,bcm2835-audio.txt         | 15 +++++++++++++++
 1 file changed, 15 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/sound/brcm,bcm2835-audio.txt

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@suse.de>
> ---
>  .../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).

Stefan

[1] - https://patchwork.ozlabs.org/cover/970434/
[2] - https://lore.kernel.org/patchwork/patch/904411/
[3] - https://github.com/anholt/linux/commits/bcm2835-audio

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@suse.de>
> > ---
> >  .../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

Hi Nicolas,

> Nicolas Saenz Julienne <nsaenzjulienne@suse.de> hat am 16. Oktober 2018 um 18:48 geschrieben:
> 
> 
> 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@suse.de>
> > > ---
> > >  .../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.

i will inform you.

> 
> 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.

You can add my

Acked-by: Stefan Wahren <stefan.wahren@i2se.com>

to patches 1 to 5. Please drop 6 to 9 from the series and add the other suggestions.

Btw please add devel@driverdev.osuosl.org to CC for V2

Thanks
Stefan

> 
> Regards,
> Nicolas