[alsa-devel] [PATCH 1/2] ASoC: wm8904: rework FLL handling

[Charles Keepax]

On Mon, Jul 22, 2019 at 07:57:21PM +0200, Michał Mirosław wrote:
> Extract and rework FLL handling. This makes it possible to reuse
> the code for other Wolfson codecs and makes codec adapt SYSCLK to
> exactly match frequency required for used sampling rate.
> 

Do you have thoughts on which CODECs you would be including in
this? These older parts often have small differences between the
configuration that might make this challenging so if you have
plans here would be good to have a look from this end.

> Signed-off-by: Michał Mirosław <mirq-linux at rere.qmqm.pl>
> ---
>  .../devicetree/bindings/sound/wm8904.txt      |   4 +
>  sound/soc/atmel/atmel_wm8904.c                |  11 +-
>  sound/soc/codecs/Kconfig                      |   4 +
>  sound/soc/codecs/Makefile                     |   2 +
>  sound/soc/codecs/wm8904.c                     | 454 +++++-------------
>  sound/soc/codecs/wm8904.h                     |   5 -
>  sound/soc/codecs/wm_fll.c                     | 339 +++++++++++++
>  sound/soc/codecs/wm_fll.h                     |  26 +
>  8 files changed, 492 insertions(+), 353 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/sound/wm8904.txt b/Documentation/devicetree/bindings/sound/wm8904.txt
> index 66bf261423b9..6b51d87f5987 100644
> --- a/Documentation/devicetree/bindings/sound/wm8904.txt
> +++ b/Documentation/devicetree/bindings/sound/wm8904.txt
> @@ -9,6 +9,10 @@ Required properties:
>    - clocks: reference to
>      <Documentation/devicetree/bindings/clock/clock-bindings.txt>
>  
> +Optional properties:
> +  - wlf,fll-input: FLL input signal: "mclk", "bclk", "lrclk" or "osc"
> +	("mclk" by default)
> +

Would be keen to see some other peoples thoughts on this one, but
this feels a little off to me. Selecting the FLL input is
generally something that would be done on a use-case by use-case
basis rather than being a property of the hardware that would
belong in device tree.

Thanks,
Charles