At Tue, 21 Oct 2008 17:35:49 +0800, Cai, Cliff wrote: > > > > >-----Original Message----- > >From: Mark Brown [mailto:broonie@xxxxxxxxxxxxx] > >Sent: Tuesday, October 21, 2008 5:16 PM > >To: Cai, Cliff > >Cc: Bryan Wu; alsa-devel@xxxxxxxxxxxxxxxx > >Subject: Re: [PATCH 2/3] ASoC: Blackfin: add multi-channel > >supporting in Blackfin ASoC driver and AD1980 codec driver > > > >On Tue, Oct 21, 2008 at 05:08:31PM +0800, Cai, Cliff wrote: > > > >> >To be honest, I'm surprised that the multi-channel support > >can't only > >> >incur the extra memory consumpton when playing back a multi-channel > >> >stream - I'd have expected the hardware to work in the same > >way for a > >> >normal stereo stream even if multi-channel support is built in. > > > >> Yes,hardware almost works in the same way as playing a stereo > >> stream,except That it need to fill more data to DMA memory > >> manually,since we just simulate AC97 Controller using serial port. > > > >My point is that the configuration of the hardware for > >multi-channel playback only needs to be done when actually > >playing back multi-channel data. When playing back stereo > >data it should be possible to configure the hardware and do > >the simulation in the same way as when multi-channel support > >is not compiled in and avoid the additional costs which that incurs. > > > >As well as saving memory I'd expect configuring this at > >runtime to also save some power when playing back two or four > >channel data. > > > > Yes, it's an ideal way,but it's not safe to allocate continuous memory > dynamicly, > Since embedded system has limited uncached DMA memory. But, CONFIG_SND_MULTICHAN_SUPPORT would change any buffer allocation behavior? I don't find it... Anyway, I agree with Mark. The setup can be ideally dynamically changed. thanks, Takashi _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
