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Subject: Re: [PATCH v2 0/5] ALSA: xen-front: Add Xen para-virtualized frontend
 driver
From:   Oleksandr Andrushchenko <andr2000@gmail.com>
To:     xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org,
        alsa-devel@alsa-project.org, jgross@suse.com,
        boris.ostrovsky@oracle.com, konrad.wilk@oracle.com, perex@perex.cz,
        tiwai@suse.com
Cc:     Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
References: <20180416062453.24743-1-andr2000@gmail.com>
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Message-ID: <198552e8-d1e2-d9e1-9636-927b0778ef9d@gmail.com>
Date:   Mon, 23 Apr 2018 09:34:26 +0300
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On 04/18/2018 06:15 PM, Oleksandr Andrushchenko wrote:
> On 04/16/2018 09:24 AM, Oleksandr Andrushchenko wrote:
>> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
>>
>> Please note: this patch series depends on [3].
> The dependency is now merged into Xen kernel tree [4] for-linus-4.17
The dependency is now pulled into Linus tree [5]
>>
>> This patch series adds support for Xen [1] para-virtualized
>> sound frontend driver. It implements the protocol from
>> include/xen/interface/io/sndif.h with the following limitations:
>> - mute/unmute is not supported
>> - get/set volume is not supported
>> Volume control is not supported for the reason that most of the
>> use-cases (at the moment) are based on scenarious where
>> unprivileged OS (e.g. Android, AGL etc) use software mixers.
>>
>> Both capture and playback are supported.
>>
>> Corresponding backend, implemented as a user-space application, can be
>> found at [2].
>>
>> Thank you,
>> Oleksandr
>>
>> Changes since v1:
>> *****************
>>
>> 1. Moved driver from sound/drivers to sound/xen
>>
>> 2. Coding style changes to better meet Linux Kernel
>>
>> 3. Added explicit back and front synchronization
>>     In order to provide explicit synchronization between backend and
>>     frontend the following changes are introduced in the protocol:
>>      - add new ring buffer for sending asynchronous events from
>>        backend to frontend to report number of bytes played by the
>>        frontend (XENSND_EVT_CUR_POS)
>>      - introduce trigger events for playback control: 
>> start/stop/pause/resume
>>      - add "req-" prefix to event-channel and ring-ref to unify naming
>>        of the Xen event channels for requests and events
>>
>> 4. Added explicit back and front parameter negotiation
>>     In order to provide explicit stream parameter negotiation between
>>     backend and frontend the following changes are introduced in the 
>> protocol:
>>     add XENSND_OP_HW_PARAM_QUERY request to read/update
>>     configuration space for the parameters given: request passes
>>     desired parameter's intervals/masks and the response to this request
>>     returns allowed min/max intervals/masks to be used.
>>
>> [1] https://xenproject.org/
>> [2] https://github.com/xen-troops/snd_be
>> [3] https://lkml.org/lkml/2018/4/12/522
>>
>> Oleksandr Andrushchenko (5):
>>    ALSA: xen-front: Introduce Xen para-virtualized sound frontend driver
>>    ALSA: xen-front: Read sound driver configuration from Xen store
>>    ALSA: xen-front: Implement Xen event channel handling
>>    ALSA: xen-front: Implement handling of shared buffers
>>    ALSA: xen-front: Implement ALSA virtual sound driver
>>
>>   sound/Kconfig                     |   2 +
>>   sound/Makefile                    |   2 +-
>>   sound/xen/Kconfig                 |  10 +
>>   sound/xen/Makefile                |   9 +
>>   sound/xen/xen_snd_front.c         | 410 +++++++++++++++++++
>>   sound/xen/xen_snd_front.h         |  57 +++
>>   sound/xen/xen_snd_front_alsa.c    | 830 
>> ++++++++++++++++++++++++++++++++++++++
>>   sound/xen/xen_snd_front_alsa.h    |  23 ++
>>   sound/xen/xen_snd_front_cfg.c     | 517 ++++++++++++++++++++++++
>>   sound/xen/xen_snd_front_cfg.h     |  46 +++
>>   sound/xen/xen_snd_front_evtchnl.c | 478 ++++++++++++++++++++++
>>   sound/xen/xen_snd_front_evtchnl.h |  92 +++++
>>   sound/xen/xen_snd_front_shbuf.c   | 193 +++++++++
>>   sound/xen/xen_snd_front_shbuf.h   |  36 ++
>>   14 files changed, 2704 insertions(+), 1 deletion(-)
>>   create mode 100644 sound/xen/Kconfig
>>   create mode 100644 sound/xen/Makefile
>>   create mode 100644 sound/xen/xen_snd_front.c
>>   create mode 100644 sound/xen/xen_snd_front.h
>>   create mode 100644 sound/xen/xen_snd_front_alsa.c
>>   create mode 100644 sound/xen/xen_snd_front_alsa.h
>>   create mode 100644 sound/xen/xen_snd_front_cfg.c
>>   create mode 100644 sound/xen/xen_snd_front_cfg.h
>>   create mode 100644 sound/xen/xen_snd_front_evtchnl.c
>>   create mode 100644 sound/xen/xen_snd_front_evtchnl.h
>>   create mode 100644 sound/xen/xen_snd_front_shbuf.c
>>   create mode 100644 sound/xen/xen_snd_front_shbuf.h
>>
> [4] 
> https://git.kernel.org/pub/scm/linux/kernel/git/xen/tip.git/commit/?h=for-linus-4.17&id=cd6e992b3aab072cc90839508aaf5573c8f7e066
[5] 
https://elixir.bootlin.com/linux/v4.17-rc2/source/include/xen/interface/io/sndif.h