On Tue, Jul 23, 2013 at 02:50:00PM +0100, Russell King - ARM Linux wrote:
Not only that, but the lack of assistance from ASoC people on the multiple substream stuff really doesn't help one iota when it comes to making forward progress with SPDIF support. I've explained to them the
It'd probably help if the people looking at this hardware started to contribute some of the work that's being done here; this should help move things forward by looking at concrete code rather than the very general discussion that's happening at the minute.
problem (SPDIF and I2S if used together must be enabled simultaneously or only one is permitted at any one time); they've suggested using the multiple PCM substream support, and then it's a case that "oh it's undocumented" "oh there's no examples yet".
As previously mentioned the OMAP4 and Qualcomm stuff is there, it's just out of tree - there's also Haswell but I'm not sure if that's been made public yet (Liam?).
And then there's the problem of understanding the ASoC DAPM stuff "oh it's just a graph walk, you don't need to know the internals" is what I get from ASoC people. Well, yes I do need to know the internals, so I can find out whether it's going to startup a second substream while a first one is active, and end up with SPDIF enabled non-concurrently with I2S.
As ever the answer is that DAPM will enable any connected audio path and not enable other ones so it is possible to enable only one of multiple paths (as you'd expect, really).
Can you be more specific about the problems you're having following the code? It should be relatively simple to trace through what's going on from dapm_power_widgets()...