On Tue, Oct 28, 2014 at 10:13:48PM +0800, Greg Kroah-Hartman wrote: > On Tue, Oct 28, 2014 at 01:18:28PM +0000, Qais Yousef wrote: > > On 10/28/2014 11:55 AM, Clemens Ladisch wrote: > > >Qais Yousef wrote: > > >>AXD Audio Processing IP performs audio decoding, encoding, mixing, equalisation, > > >>synchronisation and playback. > > >What exactly do you mean with "synchronisation" and "playback"? > > > > Synchronisation refers to accurate audio playout relative to a master > > clock source including compensation of drift between the master clock > > source and the playout clock of the audio hardware. Hence allowing > > synchronised audio playout across multiple independent devices. > > > > Playback simple refers to the fact that AXD is capable of managing audio > > playout hardware like I2S and SPDIF interfaces. > > > > > > >>It doesn't fit in alsa subsystem but I Cced them to confirm. > > >... because those two words sound like something that a sound card could do. > > > > The problem mainly stems from the fact that we take a variety of > > compressed audio as input and we could perform audio encoding. The > > problem with the compressed audio is that the range of decoders and > > configuration supported in alsa is limited and there's no support for > > taking raw pcm and producing compressed output. I'm not an expert on > > alsa but when I looked it looked like there's more infra structure > > required. > > > > The following not supported points from Documentation/sound/alsa/compress_offload.txt affect us: > > > > - Volume control/routing is not handled by this API. Devices exposing a > > compressed data interface will be considered as regular ALSA devices; > > volume changes and routing information will be provided with regular > > ALSA kcontrols. > > > > - Embedded audio effects. Such effects should be enabled in the same > > manner, no matter if the input was PCM or compressed. > > > > - Encoding/decoding acceleration is not supported as mentioned > > above. It is possible to route the output of a decoder to a capture > > stream, or even implement transcoding capabilities. This routing > > would be enabled with ALSA kcontrols. > > So instead you created a one-off api just for this hardware? Ick, no, > please work with the audio developers to incorporate it into the > standard Linux audio apis so that everyone can benifit and not require > special userspace programs to drive this hardware. I think it more a case of I want it do this by method A, ...naaaaah thats not what is availble in ALSA so let me redo the whole stack rather than model my driver to use ALSA -- ~Vinod -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
