Re: [Embedded-pv-devel] [Xen-devel] Access I2C bus from guest/DomU on ARM board

[Saumya Rajesh <saumyarajesh93@xxxxxxxxx>]

On Wed, Jan 31, 2018 at 8:36 PM, Andrii Anisov <andrii_anisov@xxxxxxxx> wrote:
> Hello Saumya,
>
>
> On 18.01.18 09:50, Saumya Rajesh wrote:
>>
>> Actually I am planning to set up Android as guest in Xen.
>
> I see.
>
>> In order to enable sound in the Android guest, I need to passthrough the
>> audio codec device which communicates through the I2C bus. For BE/FE scheme,
>> I think sharing the internal DMA and clock would pose problems. So I'm going
>> to go ahead with the device passthrough way.
>
> Passing through I2C bus to guest domain would not be enough to get sound in
> Android. You would face more dependencies, and they may appear not solvable.
>
>> Any thoughts or inputs you can possibly give regarding this use case will
>> be very helpful and valuable.
>
> We are using PV Audio solution for such a task:
>
> https://lists.xenproject.org/archives/html/xen-devel/2017-03/msg02428.html
> https://lkml.org/lkml/2017/8/7/115
>
> --
>
> *Andrii Anisov*
>
>

Hi Andrii

I guess you are right. I am already facing issues in doing I2C bus
passthrough. If you find time, please look into [1][2].

I was able to successfully build and execute the PV Audio solution on
R-Car H3, with xen-front[3] as frontend and snd_be[4] as backend. The
only issue I encountered was that Dom0 could not use the sound card as
long as the backend application ran. It is the only working solution
that I have found till now.

I think I am back to square one but I can't help but ask if you are
familiar with any work which is going on in Xen which makes it
possible for the guest domain(Linux based) to interact with all kinds
of I2C devices such as audio SoCs or sensors?

Regards
Saumya

[1] https://lists.xenproject.org/archives/html/xen-devel/2018-01/msg02711.html
[2] https://lists.xenproject.org/archives/html/xen-devel/2018-01/msg02618.html
[3] https://lists.xen.org/archives/html/xen-devel/2017-08/msg00626.html
[4] https://github.com/xen-troops/snd_be

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