[alsa-devel] [PATCH] ASoC: msm8916-wcd-digital: Reset RX interpolation path after use

[Srinivas Kandagatla]

On 05/01/2020 10:27, Stephan Gerhold wrote:
> For some reason, attempting to route audio through QDSP6 on MSM8916
> causes the RX interpolation path to get "stuck" after playing audio
> a few times. In this situation, the analog codec part is still working,
> but the RX path in the digital codec stops working, so you only hear
> the analog parts powering up. After a reboot everything works again.
> 
> So far I was not able to reproduce the problem when using lpass-cpu.
> 
> The downstream kernel driver avoids this by resetting the RX
> interpolation path after use. In mainline we do something similar
> for the TX decimator (LPASS_CDC_CLK_TX_RESET_B1_CTL), but the
> interpolator reset (LPASS_CDC_CLK_RX_RESET_CTL) got lost when the
> msm8916-wcd driver was split into analog and digital.
> 
> Fix this problem by adding the reset to
> msm8916_wcd_digital_enable_interpolator().
> 
> Fixes: 150db8c5afa1 ("ASoC: codecs: Add msm8916-wcd digital codec")
> Cc: Srinivas Kandagatla <srinivas.kandagatla at linaro.org>
> Signed-off-by: Stephan Gerhold <stephan at gerhold.net>

Thanks for the patch and testing it with QDSP6.

> ---
> Tested on msm8916-samsung-a5u:
>    - qdsp6 does no longer stop working after playing audio a few times
>    - lpass-cpu is still working fine (no difference)
> ---
>   sound/soc/codecs/msm8916-wcd-digital.c | 6 ++++++
>   1 file changed, 6 insertions(+)
> 
> diff --git a/sound/soc/codecs/msm8916-wcd-digital.c b/sound/soc/codecs/msm8916-wcd-digital.c
> index 58b2468fb2a7..09fccacadd6b 100644
> --- a/sound/soc/codecs/msm8916-wcd-digital.c
> +++ b/sound/soc/codecs/msm8916-wcd-digital.c
> @@ -586,6 +586,12 @@ static int msm8916_wcd_digital_enable_interpolator(
>   		snd_soc_component_write(component, rx_gain_reg[w->shift],
>   			      snd_soc_component_read32(component, rx_gain_reg[w->shift]));
>   		break;
> +	case SND_SOC_DAPM_POST_PMD:

We should do this in SND_SOC_DAPM_PRE_PMU rather than in power down 
sequence.


> +		snd_soc_component_update_bits(component, LPASS_CDC_CLK_RX_RESET_CTL,
> +					      1 << w->shift, 1 << w->shift);
> +		snd_soc_component_update_bits(component, LPASS_CDC_CLK_RX_RESET_CTL,
> +					      1 << w->shift, 0x0);
> +		break;
>   	}
>   	return 0;
>   }
>