Re: [PATCH] ASoC: soc-pcm: Preserve hw parameters from components in dpcm_runtime_setup_fe

["Péter Ujfalusi" <peter.ujfalusi@linux.intel.com>]

Hi Morimoto-san,

On 27/10/2025 08:11, Kuninori Morimoto wrote:
> 
> Hi Peter
> 
> Thank you for the patch
> 
>> Component drivers can prepare snd_pcm_hardware struct based on the hardware
>> capabilities which information should not be discarded.
>>
>> Only touch the rates, channels_max and formats if they were left to 0,
>> otherwise keep the provided configuration intact for the parameter cross
>> checking decision.
>>
>> Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
>> ---
> (snip)
>> -	soc_pcm_hw_init(hw);
>> -
>> -	if (formats)
>> -		hw->formats &= formats;
>> +	/*
>> +	 * Initialize only pcm hardware patameters that has not been initialized
>> +	 * and preserve the configuration which might have been provided by
>> +	 * component drivers
>> +	 */
>> +	if (!hw->rates)
>> +		hw->rates = UINT_MAX;
>> +	if (!hw->rate_max)
>> +		hw->rate_max = UINT_MAX;
>> +	if (!hw->channels_max)
>> +		hw->channels_max = UINT_MAX;
>> +	if (!hw->formats)
>> +		hw->formats = ULLONG_MAX;
> 
> soc_pcm_hw_init() is used from only 2 functions
> 
> 	(a) snd_soc_runtime_calc_hw()
> 	(b) dpcm_runtime_setup_fe()
> 
> And this patch fixed not to use it in (b).
> Setting same variable in multiple method is not good idea, IMO.
> 
> How about like this ?

This is how the RFC was done, but decided to not modify
soc_pcm_hw_init() with an added bool.
Other option would be to add a new function which would do only
conditional initialization.

https://lore.kernel.org/linux-sound/20251020073750.27784-1-peter.ujfalusi@linux.intel.com/

> 
> 	static void soc_pcm_hw_init(struct snd_pcm_hardware *hw, boot force)
> 	{
> 		if (force || !hw->rates)
> 			hw->rates		= UINT_MAX;
> 		if (force || !hw->rate_max)
> 			hw->rate_max		= UINT_MAX;
> 		if (force || !hw->channels_max)
> 			hw->channels_max	= UINT_MAX;
> 		if (force || !hw->formats)
> 			hw->formats		= ULLONG_MAX;
> 
> 		hw->rate_min		= 0;
> 		hw->channels_min	= 0;

This way we would loose the rate_min, channel_min from components, see
my RFC which covers this, but it is using reverse condition (preserve vs
force).
The force boolean might be better than the preserve_config as parameter
if the preference is to modify the soc_pcm_hw_init()

> 	}
> 
> 	int snd_soc_runtime_calc_hw(...)
> 	{
> 		...
> 		soc_pcm_hw_init(hw, true);
> 		...
> 	}
> 
> 	int dpcm_runtime_setup_fe(...)
> 	{
> 		...
> 		soc_pcm_hw_init(hw, false);
> 		...
> 	}
> 
> 
> Thank you for your help !!
> 
> Best regards
> ---
> Kuninori Morimoto

-- 
Péter