[alsa-devel] [PATCH] ASoC: tlv320aic31xx: Fix master mode clock I2S bus clocks

[Andrew F. Davis]

On 02/12/2018 09:05 AM, Peter Ujfalusi wrote:
> 
> 
> On 2018-02-12 16:17, Andrew F. Davis wrote:
>> On 02/12/2018 08:06 AM, Peter Ujfalusi wrote:
>>> In the reset state of the codec we do not have complete playback or capture
>>> routes.
>>>
>>> The audio playback/capture will not work due to missing clock signals on
>>> the I2S bus if PLL, MDAC/NDAC/DAC MADC/NADC/ADC is powered down.
>>>
>>> To make sure that even if all output/input is disconnected the codec is
>>> generating clocks, we need to have valid DAPM route in every case to power
>>> up the must needed parts of the codec.
>>>
>>
>> If all output/input is disconnected why do we need the I2C clocks?
> 
> we need I2S clocks when user is running audio, otherwise it will time
> out with error.
> 

You mean in the case were they have the device set to route the I2S
stream to a dead end inside the CODEC (DAC IN -> OFF), but still want to
push data down the I2S line?

Is there no way to communicate the device is muted back to the I2S data
master to not try to push data?

>> Or do you mean if only one is disconnected the PLL goes down?
> 
> If both is down (DACs in case of playback, ADC in case of capture)
> 
>> If that is
>> the case then it would be better to fix the DAPM route so both paths
>> correctly lead back to the PLL.
> 
> This is what the patch is doing, it makes sure that DAC/ADC is powered
> and all the other things we need for clock generation.
> 

I don't see that, to me it looks like a workaround to force the whole
DAC/ADC PLL clock chain active even when there is no route to the DAC
(or from ADC) because we need a PLL derived clock to run the I2S clocks.

I understand the need: when acting as the clock master the CODEC should
always provide a clock (right?), even when the CODEC is muted (or the
I2S signal has no route to the DAC).

But what this patch does is to leave the DAC clocks always on, even in
clock slave mode, where there is no need to have the PLL or DAC clocks
on. Is there really no other way to force the PLL always on when in
clock master mode only?

>>
>>> I have verified that switching DAC (during playback) or ADC (during
>>> capture) will stop the I2S clocks, so the only solution is to connect the
>>> 'Off' routes as well to output/input.
>>>
>>> Tested on am43x-epos-evm with aic3111 codec in master mode.
>>>
>>> Signed-off-by: Peter Ujfalusi <peter.ujfalusi at ti.com>
>>> ---
>>>  sound/soc/codecs/tlv320aic31xx.c | 9 +++++++++
>>>  1 file changed, 9 insertions(+)
>>>
>>> diff --git a/sound/soc/codecs/tlv320aic31xx.c b/sound/soc/codecs/tlv320aic31xx.c
>>> index 858cb8be445f..d42a23eb916e 100644
>>> --- a/sound/soc/codecs/tlv320aic31xx.c
>>> +++ b/sound/soc/codecs/tlv320aic31xx.c
>>> @@ -586,9 +586,11 @@ common31xx_audio_map[] = {
>>>  	{"DAC Left Input", "Left Data", "DAC IN"},
>>>  	{"DAC Left Input", "Right Data", "DAC IN"},
>>>  	{"DAC Left Input", "Mono", "DAC IN"},
>>> +	{"DAC Left Input", "Off", "DAC IN"},
>>>  	{"DAC Right Input", "Left Data", "DAC IN"},
>>>  	{"DAC Right Input", "Right Data", "DAC IN"},
>>>  	{"DAC Right Input", "Mono", "DAC IN"},
>>> +	{"DAC Right Input", "Off", "DAC IN"},
>>>  	{"DAC Left", NULL, "DAC Left Input"},
>>>  	{"DAC Right", NULL, "DAC Right Input"},
>>>  
>>> @@ -601,6 +603,9 @@ common31xx_audio_map[] = {
>>>  	{"HP Right", "Switch", "Output Right"},
>>>  	{"HPR Driver", NULL, "HP Right"},
>>>  	{"HPR", NULL, "HPR Driver"},
>>> +
>>> +	{"HPL", NULL, "DAC Left"},
>>> +	{"HPR", NULL, "DAC Right"},
>>>  };
>>>  
>>>  static const struct snd_soc_dapm_route
>>> @@ -621,16 +626,20 @@ aic31xx_audio_map[] = {
>>>  	{"MIC1LP P-Terminal", "FFR 10 Ohm", "MIC1LP"},
>>>  	{"MIC1LP P-Terminal", "FFR 20 Ohm", "MIC1LP"},
>>>  	{"MIC1LP P-Terminal", "FFR 40 Ohm", "MIC1LP"},
>>> +	{"MIC1LP P-Terminal", "Off", "MIC1LP"},
>>>  	{"MIC1RP P-Terminal", "FFR 10 Ohm", "MIC1RP"},
>>>  	{"MIC1RP P-Terminal", "FFR 20 Ohm", "MIC1RP"},
>>>  	{"MIC1RP P-Terminal", "FFR 40 Ohm", "MIC1RP"},
>>> +	{"MIC1RP P-Terminal", "Off", "MIC1RP"},
>>>  	{"MIC1LM P-Terminal", "FFR 10 Ohm", "MIC1LM"},
>>>  	{"MIC1LM P-Terminal", "FFR 20 Ohm", "MIC1LM"},
>>>  	{"MIC1LM P-Terminal", "FFR 40 Ohm", "MIC1LM"},
>>> +	{"MIC1LM P-Terminal", "Off", "MIC1LM"},
>>>  
>>>  	{"MIC1LM M-Terminal", "FFR 10 Ohm", "MIC1LM"},
>>>  	{"MIC1LM M-Terminal", "FFR 20 Ohm", "MIC1LM"},
>>>  	{"MIC1LM M-Terminal", "FFR 40 Ohm", "MIC1LM"},
>>> +	{"MIC1LM M-Terminal", "Off", "MIC1LM"},
>>>  
>>>  	{"MIC_GAIN_CTL", NULL, "MIC1LP P-Terminal"},
>>>  	{"MIC_GAIN_CTL", NULL, "MIC1RP P-Terminal"},
>>>
> 
> - Péter
> 
> Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
> Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
>