snd_pcm_lib_preallocate_pages — pre-allocation for the given DMA type
int snd_pcm_lib_preallocate_pages
(struct snd_pcm_substream * substream, int type, struct device * data, size_t size, size_t max);
the pcm substream instance
DMA type (SNDRV_DMA_TYPE_*)
DMA type dependant data
the requested pre-allocation size in bytes
the max. allowed pre-allocation size
Do pre-allocation for the given DMA buffer type.
When substream->dma_buf_id is set, the function tries to look for the reserved buffer, and the buffer is not freed but reserved at destruction time. The dma_buf_id must be unique for all systems (in the same DMA buffer type) e.g. using snd_dma_pci_buf_id.
Returns zero if successful, or a negative error code on failure.