[alsa-devel] SNDRV_PCM_INFO_MMAP - what do I need for it?

My 8610 ASoC driver has this:

static const struct snd_pcm_hardware fsl_dma_hardware = {

.info = SNDRV_PCM_INFO_INTERLEAVED,

This means that MMAP is not enabled.

I understand what MMAP is, but not from an ALSA driver perspective. If I change the above line to this:

.info = SNDRV_PCM_INFO_INTERLEAVED | SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_MMAP_VALID,

what does ALSA do differently? Do I need to define any new functions? From an application perspective, what is different?

Also, does DMIX need MMAP support?