On Tue, 2015-04-21 at 11:49 +0200, Sascha Hauer wrote: > On Mon, Apr 20, 2015 at 09:48:49PM +0100, Mark Brown wrote: > > On Mon, Apr 20, 2015 at 06:37:47AM +0200, Sascha Hauer wrote: > > > On Sat, Apr 18, 2015 at 06:34:07PM +0100, Mark Brown wrote: > > > > On Fri, Apr 10, 2015 at 04:14:07PM +0800, Koro Chen wrote: > > > > > > > +Each external interface (called "IO" in this driver) is presented as a > > > > > +DAI to ASoC. An IO must be connected via the interconnect to a memif. > > > > > +The connection paths are configured through the device tree. > > > > > > Why are these connection paths configured via device tree? I would > > > > expect that either there would be runtime configurability of these > > > > things (particularly if loopback configurations within the hardware are > > > > possible) or we'd just allocate memory interfaces to DAIs automatically > > > > as DAIs come into use. > > > > > There is a crossbar switch between the memory interfaces and the DAIs. > > > Not every connection is possible, so not every memory interface can be > > > used for every DAI. An algorithm choosing a suitable memory interface > > > must be quite clever, complicated and also SoC dependent (the same but > > > different hardware is used on MT8135 aswell), so I thought offering a > > > static configuration via device tree is a good start. Should there be > > > runtime configuration possible later the device tree settings could > > > provide a good default. > > > > What exactly do the restrictions look like and how often do they vary in > > practice (can we get away with just doing a single static setup in the > > driver)? I'd have thought it should be fairly straightforward to have a > > table of valid mappings and just pick the first free memory interface? > > I think this could be done. I checked the possible connections in the > crossbar switch and it seems all memory interfaces can be connected with > all relevant external interfaces. So indeed the memory interfaces could > be dynamically allocated instead of statically associated to an > external interface. There are two problems I see: Some memory interfaces > are limited in the rates they support, they can only do 8k/16k/32k (for > speech). How can we know such memory interface should be used? Also The 2 memif are "DAI" and "MOD_DAI", designed for speech cases, and they should be only connected to corresponding external interface "DAI/BT" and "modem", respectively. We don't need to put them into dynamic allocation. > there are two programmable hardware gain blocks which can be inserted to > the digital audio path using the crossbar switch. There must be some > mechanism to configure them into different places. Maybe in DPCM, they can be "widgets", and we can define "routes" and corresponding controls for them. > > Sascha > -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
