>-----Original Message----- >From: Takashi Iwai [mailto:tiwai@xxxxxxx] >Sent: Tuesday, October 21, 2008 6:02 PM >To: Cai, Cliff >Cc: Mark Brown; Bryan Wu; alsa-devel@xxxxxxxxxxxxxxxx >Subject: Re: [PATCH 2/3] ASoC: Blackfin: add >multi-channel supporting in Blackfin ASoC driver and AD1980 >codec driver > >At Tue, 21 Oct 2008 17:48:56 +0800, >Cai, Cliff wrote: >> >> >> >> >-----Original Message----- >> >From: Takashi Iwai [mailto:tiwai@xxxxxxx] >> >Sent: Tuesday, October 21, 2008 5:39 PM >> >To: Cai, Cliff >> >Cc: Mark Brown; Bryan Wu; alsa-devel@xxxxxxxxxxxxxxxx >> >Subject: Re: [PATCH 2/3] ASoC: Blackfin: add >> >multi-channel supporting in Blackfin ASoC driver and AD1980 codec >> >driver >> > >> >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... >> >> It will change the ac97 frame size defined in bf5xx-ac97.h,the frame >> size the basic unit of the DMA buffer > >Ah, I see. Then I find this patch OK, at least, changes for >blackfin part. >Basically MULTICHAN_SUPPORT will require more resources, but >it still provides the same functionality as without it. > >BTW, are your changes to ad1980.c applicable unconditionally? >For example, >> --- a/sound/soc/codecs/ad1980.c >> +++ b/sound/soc/codecs/ad1980.c >> @@ -145,7 +145,7 @@ struct snd_soc_dai ad1980_dai = { >> .playback = { >> .stream_name = "Playback", >> .channels_min = 2, >> - .channels_max = 2, >> + .channels_max = 6, > >This won't work if the machine side doesn't support the >multi-channel. Right now, blackfin is the only one, but the >codec driver should be generic. This is a problem,what's your suggestion? I think if the CPU DAI only supports stereo,alsa will omit the 6 channel support for codec,am I wrong? It works for me,since I provide two choices for CPU DAI,2 or 6 channel(through CONFIG_SND_MULTICHAN_SUPPORT). >Also, the below is dangerous: > >> @@ -256,6 +256,9 @@ static int ad1980_soc_probe(struct >platform_device >> *pdev) >> + ac97_write(codec, AC97_EXTENDED_STATUS, 0x0000);/*power on LFE >> +CENTER and Surround DACs*/ > >This will disable all other features, too. OK, I will only enable the DACs needed. > >thanks, > >Takashi > _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
