>-----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. _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
