[alsa-devel] writing an alsa driver

[Vinod Koul]

On Tue, Jun 23, 2015 at 11:09:33AM +0200, Michele Curti wrote:
> On Mon, Jun 15, 2015 at 06:04:28PM +0100, Liam Girdwood wrote:
> > Michele, can you change your machine driver to use the Vinods BYT DSP
> > PCM driver (base it on bytcr_rt5640.c). Please test probing/booting with
> > the current FW release from Vinod too. That way you should be ready to
> > integrate the new FW when it is released. Please also CC Vinod on any
> > issues you have getting the FW to boot using the new driver/FW.
> >
> 
> Hi,
> an update, thanks to Vinod now the driver compiles enabling only the (new)
> CONFIG_SND_SOC_INTEL_BYTCR_RT5645_MACH option.
> 
> The sound card shows up:
> [zio at asus ~]$ aplay -l
> **** List of PLAYBACK Hardware Devices ****
> card 0: baytrailcraudio [baytrailcraudio], device 0: Baytrail Audio (*) []
>   Subdevices: 1/1
>   Subdevice #0: subdevice #0
> 
> There are a lot of errors about missing backend dai:
> [    7.195570]  Baytrail Audio Port: ASoC: no backend DAIs enabled for Baytrail Audio Port
So in this driver we use DPCM, which means that you have to route Front End
to a BackEnd and then only you can open a device. Without linking to BE it
will fail

For Playback you can try:

#DSP routing
amixer -c0 sset 'codec_out0 mix 0 pcm0_in' on
amixer -c0 sset 'media0_out mix 0 media1_in' on
amixer -c0 sset 'media1_in Gain 0' 80% 
amixer -c0 sset 'media1_in Gain 0 Ramp Delay' 50
amixer -c0 sset 'media1_in Gain 0' off
amixer -c0 sset 'pcm0_in Gain 0' 80% 
amixer -c0 sset 'pcm0_in Gain 0 Ramp Delay' 50
amixer -c0 sset 'pcm0_in Gain 0' off
amixer -c0 sset 'codec_out0 Gain 0' 80%
amixer -c0 sset 'codec_out0 Gain 0 Ramp Delay' 50
amixer -c0 sset 'codec_out0 Gain 0' off

#Codec routin, if you have different one please modfiy
amixer -c0 sset "DAC MIXL INF1" on
amixer -c0 sset "DAC MIXR INF1" on
amixer -c0 sset "Stereo DAC MIXL DAC L1" on
amixer -c0 sset "Stereo DAC MIXR DAC R1" on
amixer -c0 sset "SPK MIXL DAC L1" on
amixer -c0 sset "SPK MIXR DAC R1" on
amixer -c0 sset "SPOL MIX SPKVOL L" on
amixer -c0 sset "SPOR MIX SPKVOL R" on
amixer -c0 sset "SPOL MIX DAC L1" on
amixer -c0 sset "SPOR MIX DAC R1" on
amixer -c0 sset "Speaker L" on
amixer -c0 sset "Speaker R" on
amixer -c0 sset "Headphone" off
amixer -c0 sset "Ext Spk" on

I have used this in T100.

-- 
~Vinod