On 18.05.2017 00:37, Ruslan Bilovol wrote:
This patch adds a new function 'f_uac1_acard' (f_uac1 with virtual "ALSA card") that uses recently created u_audio API. Comparing to legacy f_uac1 function implementation it doesn't require any real Audio codec to be present on the device. In f_uac1_acard audio streams are simply sinked to and sourced from a virtual ALSA sound card created using u_audio API. Legacy f_uac1 approach is to write audio samples directly to existing ALSA sound card f_uac1_acard approach is more generic/flexible one - create an ALSA sound card that represents USB Audio function and allows to be used by userspace application that may choose to do whatever it wants with the data received from the USB Host and choose to provide whatever it wants as audio data to the USB Host. f_uac1_acard also has capture support (gadget->host) thanks to easy implementation via u_audio. By default, capture interface has 48000kHz/2ch configuration, same as playback channel has. f_uac1_acard descriptors naming convention uses f_uac2 driver naming convention that makes it more common and meaningful. Comparing to f_uac1, the f_uac1_acard doesn't have volume/mute functionality. This is because the f_uac1 volume/mute feature unit was dummy implementation since that driver creation (2009) and never had any real volume control or mute functionality, so there is no any difference here. Since f_uac1_acard functionality, exposed interface to userspace (virtual ALSA card), input parameters are so different comparing to legace f_uac1, that there is no any reason to keep them in the same file/module, and separate function was created. g_audio can be built using one of existing UAC functions (f_uac1, f_uac1_acard or f_uac2) Signed-off-by: Ruslan Bilovol <ruslan.bilovol@xxxxxxxxx> --- .../ABI/testing/configfs-usb-gadget-uac1_acard | 14 + Documentation/usb/gadget-testing.txt | 45 ++ drivers/usb/gadget/Kconfig | 21 + drivers/usb/gadget/function/Makefile | 2 + drivers/usb/gadget/function/f_uac1_acard.c | 803 +++++++++++++++++++++ drivers/usb/gadget/function/u_uac1_acard.h | 41 ++ drivers/usb/gadget/legacy/Kconfig | 15 +- drivers/usb/gadget/legacy/audio.c | 53 ++ 8 files changed, 992 insertions(+), 2 deletions(-) create mode 100644 Documentation/ABI/testing/configfs-usb-gadget-uac1_acard create mode 100644 drivers/usb/gadget/function/f_uac1_acard.c create mode 100644 drivers/usb/gadget/function/u_uac1_acard.h
Tested on iMX7D using chipidea usb gadget controller. Tested Windows 10 and Linux 4.11 as host. Both work fine.
Tested-by: Julian Scheel <julian@xxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
