On Wed, Jun 23, 2021 at 12:23 AM Mark Brown <broonie@xxxxxxxxxx> wrote: > > On Wed, Jun 23, 2021 at 12:10:53AM +0800, Judy Hsiao wrote: > > > Thanks for your review comment. > > This patch is used to support multi-channel where we want one codec to > > control the only GPIO shared by 4 amps. > > So you've got 4 instances of the same CODEC? Then I'd expect to see > those all individually represented in DT. Or if there's a single > physical CODEC then I'm not sure what the dummies are for? > > > In snd_soc_runtime_calc_hw(), by creating dummy codecs that share a > > DAI link with a real codec: > > 1. The min/ max channel of CPU DAI will be directly adopted. > > 2. The formats and sample rates of the DAI link will be determined > > by the real codec unless the real codec supports the rate > > and format that do not intersect with the rate and format of > > snd-soc-dummy. > > That is the reason why we don’t specify the format and sample rates of > > the dummy codec with the real codec determining the properties . > > It's not clear to me why you'd not just describe the actual CODECs here > rather than using a dummy CODEC, the fact that the dummy CODEC is doing > what you want is just an accident of the implementation rather than a > description of the hardware. Thanks for your inputs. Specifying four codes for the multi-channel works fine. We have not thought of specifying four codes before as we want to avoid loading the codec driver multiple times, but actually loading the snd-soc-dummy just has the similar cost. By specifying four codes, the dtsi file describes the real hardware schematic. I will specify four codec in the dtsi file to support the four channel use case and this snd-soc-dummy patch is not needed. Thanks for the discussion!
