On 22 August 2011 17:00, Felipe Balbi <balbi@xxxxxx> wrote: > Hi, > > On Fri, Aug 19, 2011 at 04:52:14PM +0530, Jassi Brar wrote: >> This is a flexible USB Audio Class 2.0 compliant gadget driver that >> implements a simple topology with a virtual sound card exposed at >> the function side. >> >> The driver doesn't expect any real audio codec to be present on the >> function - the audio streams are simply sinked to and sourced from a >> virtual ALSA sound card created. The user-space application 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. >> >> Capture(USB-Out) and Playback(USB-In) can be run at independent >> configurations specified via module parameters while loading the driver. >> >> Signed-off-by: Yadi Brar <yadi.brar01@xxxxxxxxx> >> Signed-off-by: Jassi Brar <jassisinghbrar@xxxxxxxxx> >> --- >> >> =========== >> How To Test >> =========== >> USB_DEV$ insmod g_audio2.ko c_srate=64000 p_srate=48000 ; say >> gadget: high speed config #1: UAC2 >> >> USB_DEV$ aplay -l >> **** List of PLAYBACK Hardware Devices **** >> card 0: uac2 [uac2], device 0: UAC2 PCM [UAC2 PCM] >> Subdevices: 1/1 >> Subdevice #0: subdevice #0 >> >> USB_DEV$ arecord -l >> **** List of CAPTURE Hardware Devices **** >> card 0: uac2 [uac2], device 0: UAC2 PCM [UAC2 PCM] >> Subdevices: 1/1 >> Subdevice #0: subdevice #0 >> >> USB_HOST$ aplay -l >> **** List of PLAYBACK Hardware Devices **** >> card 0: PCH [HDA Intel PCH], device 0: ALC665 Analog [ALC665 Analog] >> Subdevices: 0/1 >> Subdevice #0: subdevice #0 >> card 1: Gadget [UAC2 Gadget], device 0: USB Audio [USB Audio] <<<<<< >> Subdevices: 1/1 >> Subdevice #0: subdevice #0 >> >> USB_HOST$ arecord -l >> **** List of CAPTURE Hardware Devices **** >> card 0: PCH [HDA Intel PCH], device 0: ALC665 Analog [ALC665 Analog] >> Subdevices: 1/1 >> Subdevice #0: subdevice #0 >> card 1: Gadget [UAC2 Gadget], device 0: USB Audio [USB Audio] <<<<<<< >> Subdevices: 1/1 >> Subdevice #0: subdevice #0 >> >> After this confirmation, you should be able to use it just like another >> sound card in your system. That is, a new sound card should appear in the >> sound preferences which you can select to route your default audio to and >> from. >> >> ============ >> Test Results >> ============ >> The driver has been tested for Half as well as Full Duplex at >> Stereo, S16_LE at 44.1KHz, 48KHz and 64KHz. It should also >> work for other configurations as well, except for different >> sample-size(TODO). >> >> Obviously, much depends upon the underlying UDC driver. >> >> While testing with OMAP's implementation of Inventra HDRC, I observed >> some noise for configurations for which the USB-OUT packet size chosen >> by the Host is not a power of 2. USB-IN works just fine. >> For ex, on both Beagle/Panda board, 48KHz USB-OUT has some noise while >> 64KHz is smooth. Also, with full duplex, it occasioanally shows noise. >> >> Taking benefit of doubt, I assume this driver has unmasked some subtle >> bug in the underlying UDC's ISOCH handling code ;) >> Please feel free to find issue with this driver by testing it over >> some other UDC. >> >> drivers/usb/gadget/Kconfig | 20 + >> drivers/usb/gadget/Makefile | 2 + >> drivers/usb/gadget/audio2.c | 155 +++++ >> drivers/usb/gadget/f_audio2.c | 1448 +++++++++++++++++++++++++++++++++++++++++ >> 4 files changed, 1625 insertions(+), 0 deletions(-) >> create mode 100644 drivers/usb/gadget/audio2.c >> create mode 100644 drivers/usb/gadget/f_audio2.c >> >> diff --git a/drivers/usb/gadget/Kconfig b/drivers/usb/gadget/Kconfig >> index e35dfef..95c65d8 100644 >> --- a/drivers/usb/gadget/Kconfig >> +++ b/drivers/usb/gadget/Kconfig >> @@ -599,6 +599,26 @@ config USB_ZERO_HNPTEST >> the "B-Peripheral" role, that device will use HNP to let this >> one serve as the USB host instead (in the "B-Host" role). >> >> +config USB_AUDIO_2 >> + tristate "Audio Gadget Class 2.0 (EXPERIMENTAL)" >> + depends on SND && EXPERIMENTAL >> + select SND_PCM >> + help >> + This Gadget Audio driver is compatible with USB Audio Class >> + specification 2.0. It implements 1 AudioControl interface, >> + 1 AudioStreaming Interface each for USB-OUT and USB-IN. >> + Number of channels, sample rate and sample size can be >> + specified as module parameters. >> + This driver doesn't expect any real Audio codec to be present >> + on the device - the audio streams are simply sinked to and >> + sourced from a virtual ALSA sound card created. The user-space >> + application 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. >> + >> + Say "y" to link the driver statically, or "m" to build a >> + dynamically linked module called "g_audio2". >> + >> config USB_AUDIO >> tristate "Audio Gadget (EXPERIMENTAL)" >> depends on SND >> diff --git a/drivers/usb/gadget/Makefile b/drivers/usb/gadget/Makefile >> index 7409338..fa8472e 100644 >> --- a/drivers/usb/gadget/Makefile >> +++ b/drivers/usb/gadget/Makefile >> @@ -40,6 +40,7 @@ obj-$(CONFIG_USB_COMPOSITE) += usb-composite.o >> # >> g_zero-y := zero.o >> g_audio-y := audio.o >> +g_audio2-y := audio2.o > > instead of adding a new gadget driver, can't you just re-use g_audio and > add what's missing ? > Hi Felipe, Functionality wise, audio.c hardcodes the data-path to the physical audio-codec onboard whereas audio2.c provides user-space with a virtual sound-card to fool around with audio-data the way the user wants. The functionality that has lion's share of code. Also, although the functionality of audio.c can be achieved by audio2.c (but not vice-versa) we'll break user-space by changing the behavior of audio.c to audio2.c Besides fundamental differences in functionality, they differ by Usb-Audio-Class compliance as well. audio.c is UAC_1 compliant, whereas audio2.c is UAC_2 complaint. One can not replace the other. For ex, MS-Windows doesn't support UAC_2 by default yet, Linux does reasonably well. And by definition having Linux-USB-Gadget support UAC_2 also, is only better. So by having both we cover more ground than by having just one. Thanks -jassi -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
