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

[Srinivas Kandagatla <srinivas.kandagatla@linaro.org>]

On 13/01/2020 13:10, Stephan Gerhold wrote:
> On Mon, Jan 13, 2020 at 11:30:48AM +0000, Srinivas Kandagatla wrote:
>>
>>
>> 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@linaro.org>
>>> Signed-off-by: Stephan Gerhold <stephan@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.
>>
> 
> Thanks for the suggestion! Any particular reason for this?
> 
> I used earlier versions of your msm8916-wcd patch series and the
> downstream driver as a base, and it does this in POST_PMD:

Normally I would have expected that we reset as part of up sequence and 
continue rather than during down.
Both of them will work!
For consistency reasons as we did this in down path for TX.

Reviewed-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>

Thanks,
srini
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