Re: [PATCH] ASoC: wm8962: Wait for updated value of WM8962_CLOCKING1 register

[Charles Keepax]

On Mon, Nov 07, 2022 at 02:38:18PM +0800, Chancel Liu wrote:
> DSPCLK_DIV field in WM8962_CLOCKING1 register is used to generate
> correct frequency of LRCLK and BCLK. Sometimes the read-only value
> can't be updated timely after enabling SYSCLK. This results in wrong
> calculation values. Delay is introduced here to wait for newest value
> from register. The time of the delay should be at least 500~1000us
> according to test.
> 
> Signed-off-by: Chancel Liu <chancel.liu@xxxxxxx>
> ---
>  sound/soc/codecs/wm8962.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/sound/soc/codecs/wm8962.c b/sound/soc/codecs/wm8962.c
> index b4b4355c6728..563843565f68 100644
> --- a/sound/soc/codecs/wm8962.c
> +++ b/sound/soc/codecs/wm8962.c
> @@ -2503,6 +2503,14 @@ static void wm8962_configure_bclk(struct snd_soc_component *component)
>  		snd_soc_component_update_bits(component, WM8962_CLOCKING2,
>  				WM8962_SYSCLK_ENA_MASK, WM8962_SYSCLK_ENA);
>  
> +	/* DSPCLK_DIV field in WM8962_CLOCKING1 register is used to generate
> +	 * correct frequency of LRCLK and BCLK. Sometimes the read-only value
> +	 * can't be updated timely after enabling SYSCLK. This results in wrong
> +	 * calculation values. Delay is introduced here to wait for newest
> +	 * value from register. The time of the delay should be at least
> +	 * 500~1000us according to test.
> +	 */
> +	msleep(1);

This looks reasonable but for a 1ms delay we should really be
using usleep_range rather than msleep.

Thanks,
Charles