Re: [PATCH 2/4] ASoC: wm8940: Rewrite code to set proper clocks

Charles Keepax
2022-12-14T13:32:32Z

On Wed, Dec 14, 2022 at 01:37:41PM +0100, Lukasz Majewski wrote:
> Without this change, the wm8940 driver is not working when
> set_sysclk callback (wm8940_set_dai_sysclk) is called with
> frequency not listed in the switch clause.
>
> This change adjusts this driver to allow non-standard frequency
> set (just after the boot) being adjusted afterwards by the sound
> system core code.
>
> Moreover, support for internal wm8940's PLL is provided, so it
> can generate clocks when HOST system is not able to do it.
>
> Code in this commit is based on previous change done for wm8974
> (SHA1: 51b2bb3f2568e6d9d81a001d38b8d70c2ba4af99).
>
> Signed-off-by: Lukasz Majewski <lukma@denx.de>
> ---
> struct snd_soc_component *component = dai->component;
> + struct wm8940_priv *priv = snd_soc_component_get_drvdata(component);
> u16 iface = snd_soc_component_read(component, WM8940_IFACE) & 0xFD9F;
> u16 addcntrl = snd_soc_component_read(component, WM8940_ADDCNTRL) & 0xFFF1;
> u16 companding = snd_soc_component_read(component,
> WM8940_COMPANDINGCTL) & 0xFFDF;
> int ret;
>
> + priv->fs = params_rate(params);
> + ret = wm8940_update_clocks(dai);
> + if (ret)
> + return ret;
> +

I think this all looks mostly good, my only slight concern would
be the interaction with the manual functions for settings the PLL
etc. I guess under this code, whatever manual settings were
configured will be overwritten with the new auto settings, I
think this should be fine as the PLL wants to be run in a pretty
narrow band anyway, so the settings are likely identical. Do you
have any thoughts?

Thanks,
Charles