Re: [PATCH v2 3/3] usb: gadget: add f_uac1 variant based on new u_audio api

[Peter Chen <hzpeterchen@gmail.com>]

On Sun, Aug 14, 2016 at 01:21:24AM +0300, Ruslan Bilovol wrote:
> This patch adds new function f_uac1_newapi that
> uses recently created u_audio api. This makes
> f_uac1_newapi implementation much simpler by
> reusing existing u_audio core utilities.
> 
> This also drops previous f_uac1 approach (write
> audio samples directly to existing ALSA sound
> card) and moves to more generic/flexible
> one - create an f_uac1 ALSA sound card that
> represents USB Audio function and allows to
> be used by userspace tools.
> 
> f_uac1_newapi also has capture support (gadget->host).
> By default, capture interface has 48000kHz/2ch
> configuration, same as playback channel has.
> 
> f_uac1_newapi descriptors naming conventios
> uses f_uac2 driver naming convention that
> makes it more common and meaningful.
> 
> Comparing to f_uac1, the f_uac1_newapi doesn't
> have volume/mute functionality. This is because
> the volume/mute feature unit was dummy
> implementation since that driver creation (2009)
> and never had real volume control or mute
> functionality.
> 
> g_audio can be built using one of existing
> uac functions (f_uac1, f_uac1_newapi or f_uac2)
> 
> Signed-off-by: Ruslan Bilovol <ruslan.bilovol@gmail.com>
> ---
>  .../ABI/testing/configfs-usb-gadget-uac1_newapi    |  12 +
>  Documentation/usb/gadget-testing.txt               |  41 ++
>  drivers/usb/gadget/Kconfig                         |  21 +
>  drivers/usb/gadget/function/Makefile               |   2 +
>  drivers/usb/gadget/function/f_uac1_newapi.c        | 795 +++++++++++++++++++++
>  drivers/usb/gadget/function/u_uac1_newapi.h        |  39 +
>  drivers/usb/gadget/legacy/Kconfig                  |  15 +-
>  drivers/usb/gadget/legacy/audio.c                  |  52 ++
>  8 files changed, 975 insertions(+), 2 deletions(-)
>  create mode 100644 Documentation/ABI/testing/configfs-usb-gadget-uac1_newapi
>  create mode 100644 drivers/usb/gadget/function/f_uac1_newapi.c
>  create mode 100644 drivers/usb/gadget/function/u_uac1_newapi.h
> 
> diff --git a/Documentation/ABI/testing/configfs-usb-gadget-uac1_newapi b/Documentation/ABI/testing/configfs-usb-gadget-uac1_newapi
> new file mode 100644
> index 0000000..d355275
> --- /dev/null
> +++ b/Documentation/ABI/testing/configfs-usb-gadget-uac1_newapi
> @@ -0,0 +1,12 @@
> +What:		/config/usb-gadget/gadget/functions/uac1_newapi.name
> +Date:		Aug 2016
> +KernelVersion:	4.9
> +Description:
> +		The attributes:
> +
> +		c_chmask - capture channel mask
> +		c_srate - capture sampling rate
> +		c_ssize - capture sample size (bytes)
> +		p_chmask - playback channel mask
> +		p_srate - playback sampling rate
> +		p_ssize - playback sample size (bytes)
> diff --git a/Documentation/usb/gadget-testing.txt b/Documentation/usb/gadget-testing.txt
> index 5819605..4598d7f 100644
> --- a/Documentation/usb/gadget-testing.txt
> +++ b/Documentation/usb/gadget-testing.txt
> @@ -20,6 +20,7 @@ provided by gadgets.
>  17. UAC2 function
>  18. UVC function
>  19. PRINTER function
> +20. UAC1 function (new API)
>  
>  
>  1. ACM function
> @@ -770,3 +771,43 @@ host:
>  
>  More advanced testing can be done with the prn_example
>  described in Documentation/usb/gadget-printer.txt.
> +
> +
> +20. UAC1 function (new API, using u_audio)
> +=================
> +
> +The function is provided by usb_f_uac1_newapi.ko module.
> +
> +Function-specific configfs interface
> +------------------------------------
> +
> +The function name to use when creating the function directory
> +is "uac1_newapi". The uac1_newapi function provides these attributes
> +in its function directory:
> +
> +	c_chmask - capture channel mask
> +	c_srate - capture sampling rate
> +	c_ssize - capture sample size (bytes)
> +	p_chmask - playback channel mask
> +	p_srate - playback sampling rate
> +	p_ssize - playback sample size (bytes)
> +
> +The attributes have sane default values.
> +
> +Testing the UAC1 function
> +-------------------------
> +
> +device: run the gadget
> +host: aplay -l # should list our USB Audio Gadget
> +
> +This function does not require real hardware support, it just
> +sends a stream of audio data to/from the host. In order to
> +actually hear something at the device side, a command similar
> +to this must be used at the device side:
> +
> +$ arecord -f dat -t wav -D hw:2,0 | aplay -D hw:0,0 &
> +
> +e.g.:
> +
> +$ arecord -f dat -t wav -D hw:CARD=UAC1Gadget,DEV=0 | \
> +aplay -D default:CARD=OdroidU3
> diff --git a/drivers/usb/gadget/Kconfig b/drivers/usb/gadget/Kconfig
> index a25afd8..abcb539 100644
> --- a/drivers/usb/gadget/Kconfig
> +++ b/drivers/usb/gadget/Kconfig
> @@ -194,6 +194,9 @@ config USB_F_FS
>  config USB_F_UAC1
>  	tristate
>  
> +config USB_F_UAC1_NEWAPI
> +	tristate
> +
>  config USB_F_UAC2
>  	tristate
>  
> @@ -397,6 +400,24 @@ config USB_CONFIGFS_F_UAC1
>  	  This driver requires a real Audio codec to be present
>  	  on the device.
>  
> +config USB_CONFIGFS_F_UAC1_NEWAPI
> +	bool "Audio Class 1.0 (new API)"
> +	depends on USB_CONFIGFS
> +	depends on SND
> +	select USB_LIBCOMPOSITE
> +	select SND_PCM
> +	select USB_U_AUDIO
> +	select USB_F_UAC1_NEWAPI
> +	help
> +	  This Audio function implements 1 AudioControl interface,
> +	  1 AudioStreaming Interface each for USB-OUT and USB-IN.

%s/1/one

-- 

Best Regards,
Peter Chen