Re: [RFC PATCH 0/5] USB Audio Gadget refactoring

From: Ruslan Bilovol <ruslan.bilovol@gmail.com>
To: Felipe Balbi <balbi@kernel.org>
Cc: Daniel Mack <zonque@gmail.com>,
	Jassi Brar <jassisinghbrar@gmail.com>,
	"linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH 0/5] USB Audio Gadget refactoring
Date: Fri, 15 Jul 2016 00:38:21 +0300	[thread overview]
Message-ID: <CAB=otbRK6r2eNagQySizvozjttEdHTBD_9kdEu3xTmt8=nCZ9w@mail.gmail.com> (raw)
In-Reply-To: <CAB=otbRg9Xh_qhzw4joR24FtZCyJE=fPpgsj+N3UiTeGY1MhFg@mail.gmail.com>

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On Wed, Jun 8, 2016 at 11:03 AM, Ruslan Bilovol
<ruslan.bilovol@gmail.com> wrote:
> Hi guys,
>
> Any feedback on this patch series? Has anybody had a chance to test it?
>
> Regards,
> Ruslan
>
> On Tue, May 24, 2016 at 2:50 AM, Ruslan Bilovol
> <ruslan.bilovol@gmail.com> wrote:
>> I came to this patch series when wanted to do two things:
>>  - use UAC1 as virtual ALSA sound card on gadget side,
>>    just like UAC2 is used so it's possible to do rate
>>    resampling
>>  - have both playback/capture support in UAC1
>>
>> Since I wanted to have same behavior for both UAC1/UAC2,
>> obviously I've got an utility part (u_audio.c) for
>> virtual ALSA sound card handling like we have
>> for ethernet(u_ether) or serial(u_serial) functions.
>> Function-specific parts (f_uac1/f_uac2) became almost
>> as storage for class-specfic USB descriptors, some
>> boilerplate for configfs, binding and few USB
>> config request handling.
>>
>> Major change to f_uac1 it that it can't do
>> direct play to existing ALSA sound card anymore,
>> representing audio on gadget side as virtual
>> ALSA sound card where audio streams are simply
>> sinked to and sourced from it, so it may break
>> current usecase for some people (and that's why
>> it's RFC).
>>
>> Luckily, it's possible to use existing user-space
>> applications for audio routing between Audio Gadget
>> and real sound card. I personally use alsaloop tool
>> from alsautils and have ability to create PCM
>> loopback between two different ALSA cards using
>> rate resampling, which is not possible with previous
>> "direct play to ALSA card" approach in f_uac1.
>>
>> While here, also dropped redundant platform
>> driver/device creation in f_uac2 driver as well as
>> "never implemented" volume/mute functionality in f_uac1
>> that made this work even easier to do.
>>
>> This series is tested with both legacy g_audio.ko and
>> modern configfs approaches under Ubuntu 14.04 (UAC1 and
>> UAC2) and under Windows7 x64 (UAC1 only) having
>> perfect results in all cases.
>>
>> Some changes may have lack of good description that may
>> be obvious for me but not so clear for others, but I
>> hope to fix it in next versions.
>>
>> Comments, testing are welcome.
>>
>> Ruslan Bilovol (5):
>>   usb: gadget: f_uac2: remove platform driver/device creation
>>   usb: gadget: f_uac2: split out audio core
>>   usb: gadget: f_uac1: drop volume/mute functionality
>>   usb: gadget: f_uac1: switch to u_audio core utilities
>>   usb: gadget: f_uac1: add capture support
>>
>>  drivers/usb/gadget/Kconfig            |  13 +-
>>  drivers/usb/gadget/function/Makefile  |   3 +-
>>  drivers/usb/gadget/function/f_uac1.c  | 842 +++++++++++++---------------------
>>  drivers/usb/gadget/function/f_uac2.c  | 778 ++++---------------------------
>>  drivers/usb/gadget/function/u_audio.c | 632 +++++++++++++++++++++++++
>>  drivers/usb/gadget/function/u_audio.h |  93 ++++
>>  drivers/usb/gadget/function/u_uac1.c  | 314 -------------
>>  drivers/usb/gadget/function/u_uac1.h  |  71 +--
>>  drivers/usb/gadget/legacy/Kconfig     |   1 +
>>  drivers/usb/gadget/legacy/audio.c     |  54 ++-
>>  10 files changed, 1208 insertions(+), 1593 deletions(-)
>>  create mode 100644 drivers/usb/gadget/function/u_audio.c
>>  create mode 100644 drivers/usb/gadget/function/u_audio.h
>>  delete mode 100644 drivers/usb/gadget/function/u_uac1.c
>>
>> --
>> 1.9.1
>>