On Tue, Aug 10, 2010 at 02:47:55PM +0100, Mark Brown wrote: > On Tue, Aug 10, 2010 at 03:38:18PM +0200, Sascha Hauer wrote: > > > I'm wondering what exactly a snd_soc_platform is. Apparently the > > snd_pcm_ops/pcm_new/pcm_free are specific to a platform. For my > > understanding these operations are more specific to a cpu_dai. Looking > > at the tree it seems that each cpu_dai has exactly one possible > > platform, which seems logical to me because the cpu_dai knows how to > > transfer the data. > > They're for the DMA bit of the CPU. While most platforms have a single > DMA controller (though some have more than one) it's moderately common > to have more than one DAI (eg, dedicated I2S and DSP mode controllers > rather than a programmable serial port, or an AC'97 controller) so it's > useful to share the DMA code. I didn't want to question that it's useful to share the code. It's just that in current i.MX implementation it would be simple to instantiate snd_pcm_ops (of fiq or dma type) in the platform_driver probe function passing all needed data like dma request line, fifo address and the like. Passing this data through the soc-core seems not very convenient. > > > My problem on i.MX is that I currently have two possible cpu dais > > (imx-ssi.[01]) and each can be configured to use dma or fiq depending > > on the dma capabilities. So the cpu_dai knows which pcm_ops we have > > to use, but currently it's the soc glue code which has to decide in > > platform_name. Am I understanding something wrong here? > > This is mostly a holdover from the existing (current mainline) ASoC > structuring at the minute, that also has the DMA configured per machine. > This may change depending on future hardware requirements, though. I would welcome such change. /Me is looking further to make the i.MX part working on multi-component. Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
