[RFC PATCH 0/3] Separate BE DAI HW constraints from FE ones

[Codrin.Ciubotariu at microchip.com]

On 23.03.2021 14:15, Jaroslav Kysela wrote:
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> Dne 23. 03. 21 v 12:43 Codrin Ciubotariu napsal(a):
> 
>> To achieve this, the first thing needed is to detect whether a HW
>> constraint rule is enforced by a FE or a BE DAI. This means that
>> snd_pcm_hw_rule_add() needs to be able to differentiate between the two
>> type of DAIs. For this, the runtime pointer to struct snd_pcm_runtime is
>> replaced with a pointer to struct snd_pcm_substream, to be able to reach
>> substream->pcm->internal to differentiate between FE and BE DAIs.
> 
> Think about other not-so-invasive solution. What about to use
> 'runtime->private_data' (struct snd_soc_pcm_runtime *) to determine FE / BE?
> 

I think struct snd_soc_pcm_runtime * is placed in 
substream->private_data, while runtime->private_data is used more by the 
platform drivers. runtime->trigger_master could be an idea, but it looks 
like it's initialized just before the trigger callback is called, way 
after the constraint rules are added and I am not sure it can be 
initialized earlier...

Best regards,
Codrin