Re: struct snd_pcm_ops callbacks

On 1/25/23 05:21, Muni Sekhar wrote:

Hi,

struct snd_pcm_ops callbacks can be used for sending\receiving PDM audio data to and from a sound card? Or is it only designed for PCM audio data?

It depends what side of the sound card you are looking at, the physical interface with external devices or the userspace interface.

PDM can be supported at the physical interface level as long as there is a conversion to PCM somewhere in the hardware. Userspace will play/record PCM. See examples in many codecs and SOCs.

There is also the possibility of packing PDM (aka DSD) as pseudo-PCM, that's a trick used by several USB cards. In that case of course the sound card cannot apply any processing to the data and is just a pass-through module.