At Thu, 24 Jun 2010 03:50:17 +0530, Adish Kuvelker wrote: > > Hello, > > I am trying to allocate memory for DMA buffer through > "snd_pcm_lib_malloc_pages" in hw_params callout function, with prior > use of "snd_pcm_lib_preallocate_pages_for_all". The chapter on PCM > Interface in "writing an ALSA driver" states that if the standard > function "snd_pcm_lib_malloc_pages" is use for allocating the DMA > buffers then the DMA fields of dma_addr, dma_area, dma_bytes are set > by the ALSA middle layer. > > However my code walk through didn't point me to the area where this > physical memory setting is done. My DMA channel is not serving a PCI > device. I would be very grateful if any of you guys can point me to > the code where this settings get done by calling > "snd_pcm_lib_malloc_pages". snd_pcm_lib_*_pages() works only with the preallocated buffers, and the pre-allocation can be done with the generic struct device, as long as the device (bus) supports dma_alloc_coherent() properly. But this can be pretty arch-specific, so better to clarify more your hardware if you need detailed answers... Takashi _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
