Re: I2S driver for implants

Re: I2S driver for implants

[Vasily Khoruzhick]

On Wed, Jul 23, 2014 at 11:10 AM, Matt Flax <flatmax@flatmax.org> wrote:
> Hi there,

Hi Matt,

I'd suggest you include alsa-devel ML next time (added it to CC)

> I saw your driver sound/soc/samsung
>
> I am wanting to look into an I2S driver for the Exynos 5250 for eye
> implants.

Driver for I2S in Exynos 5 is already included in mainline kernel.

> The implants use a serial bus and I am wanting to specify an I2S connection
> to them.
>
> In order to do that I would need to write an I2S driver to talk to them.
> Their bit rates are either 300 kbps or 600 kbps.
> They only need I2S and not I2C ... there are not controls, simply serial
> data in and out.

Are you sure that your implants can talk over I2S?

> I am wondering if I can do something simple ... I notice that your driver
> doesn't require too much code ...
> Do you think it is possible for me to take a similar approach in writing my
> implant driver ?

Don't know, you didn't share much details on your hardware.

> Can you give me advice - how to start ?

Start with reading specs and try to understand how your implants work,
then look at existing code and try to adapt it for your usage.
Then clean it up and prepare for submitting into mainline.

> thanks
> Matt

Regards,
Vasily

Re: I2S driver for implants

[Matt Flax]

On 23/07/14 18:23, Vasily Khoruzhick wrote:
> On Wed, Jul 23, 2014 at 11:10 AM, Matt Flax <flatmax@flatmax.org> wrote:
>> Hi there,
> Hi Matt,
>
> I'd suggest you include alsa-devel ML next time (added it to CC)
>
>> I saw your driver sound/soc/samsung
>>
>> I am wanting to look into an I2S driver for the Exynos 5250 for eye
>> implants.
> Driver for I2S in Exynos 5 is already included in mainline kernel.
>
>> The implants use a serial bus and I am wanting to specify an I2S connection
>> to them.
>>
>> In order to do that I would need to write an I2S driver to talk to them.
>> Their bit rates are either 300 kbps or 600 kbps.
>> They only need I2S and not I2C ... there are not controls, simply serial
>> data in and out.
> Are you sure that your implants can talk over I2S?

Yes, we do/will have custom hardware to reconstruct the required signals 
from the I2S lines.
>> I am wondering if I can do something simple ... I notice that your driver
>> doesn't require too much code ...
>> Do you think it is possible for me to take a similar approach in writing my
>> implant driver ?
> Don't know, you didn't share much details on your hardware.

The hardware requires one I2S output line and one I2S input line + the 
clock line.

You say "Driver for I2S in Exynos 5 is already included in mainline 
kernel." ... do you mean that all I need is a device tree file to enable 
it ? If so, then can you please link me to an example device tree ... my 
assumption is that this I2S device will show up in alsa once the device 
tree is setup ?

>> Can you give me advice - how to start ?
> Start with reading specs and try to understand how your implants work,
> then look at existing code and try to adapt it for your usage.
> Then clean it up and prepare for submitting into mainline.

>> thanks
>> Matt
> Regards,
> Vasily

Re: I2S driver for implants

[Vasily Khoruzhick]

On 23 July 2014 19:43:38 Matt Flax wrote:
> On 23/07/14 18:23, Vasily Khoruzhick wrote:
> > On Wed, Jul 23, 2014 at 11:10 AM, Matt Flax <flatmax@flatmax.org> wrote:
> >> Hi there,
> > 
> > Hi Matt,
> > 
> > I'd suggest you include alsa-devel ML next time (added it to CC)
> > 
> >> I saw your driver sound/soc/samsung
> >> 
> >> I am wanting to look into an I2S driver for the Exynos 5250 for eye
> >> implants.
> > 
> > Driver for I2S in Exynos 5 is already included in mainline kernel.
> > 
> >> The implants use a serial bus and I am wanting to specify an I2S
> >> connection
> >> to them.
> >> 
> >> In order to do that I would need to write an I2S driver to talk to them.
> >> Their bit rates are either 300 kbps or 600 kbps.
> >> They only need I2S and not I2C ... there are not controls, simply serial
> >> data in and out.
> > 
> > Are you sure that your implants can talk over I2S?
> 
> Yes, we do/will have custom hardware to reconstruct the required signals
> from the I2S lines.
> 
> >> I am wondering if I can do something simple ... I notice that your driver
> >> doesn't require too much code ...
> >> Do you think it is possible for me to take a similar approach in writing
> >> my
> >> implant driver ?
> > 
> > Don't know, you didn't share much details on your hardware.
> 
> The hardware requires one I2S output line and one I2S input line + the
> clock line.
> 
> You say "Driver for I2S in Exynos 5 is already included in mainline
> kernel." ... do you mean that all I need is a device tree file to enable
> it ? If so, then can you please link me to an example device tree ... my
> assumption is that this I2S device will show up in alsa once the device
> tree is setup ?

You'd probably need some codec stub, I'm not sure if it's possible to 
instantiate soundcard with only i2s and without a codec.

Regards
Vasily

> >> Can you give me advice - how to start ?
> > 
> > Start with reading specs and try to understand how your implants work,
> > then look at existing code and try to adapt it for your usage.
> > Then clean it up and prepare for submitting into mainline.
> > 
> >> thanks
> >> Matt
> > 
> > Regards,
> > Vasily

Re: I2S driver for implants

[Matt Flax]

On 23/07/14 19:52, Vasily Khoruzhick wrote:
> On 23 July 2014 19:43:38 Matt Flax wrote:
>> On 23/07/14 18:23, Vasily Khoruzhick wrote:
>>> On Wed, Jul 23, 2014 at 11:10 AM, Matt Flax <flatmax@flatmax.org> wrote:
>>>> Hi there,
>>> Hi Matt,
>>>
>>> I'd suggest you include alsa-devel ML next time (added it to CC)
>>>
>>>> I saw your driver sound/soc/samsung
>>>>
>>>> I am wanting to look into an I2S driver for the Exynos 5250 for eye
>>>> implants.
>>> Driver for I2S in Exynos 5 is already included in mainline kernel.
>>>
>>>> The implants use a serial bus and I am wanting to specify an I2S
>>>> connection
>>>> to them.
>>>>
>>>> In order to do that I would need to write an I2S driver to talk to them.
>>>> Their bit rates are either 300 kbps or 600 kbps.
>>>> They only need I2S and not I2C ... there are not controls, simply serial
>>>> data in and out.
>>> Are you sure that your implants can talk over I2S?
>> Yes, we do/will have custom hardware to reconstruct the required signals
>> from the I2S lines.
>>
>>>> I am wondering if I can do something simple ... I notice that your driver
>>>> doesn't require too much code ...
>>>> Do you think it is possible for me to take a similar approach in writing
>>>> my
>>>> implant driver ?
>>> Don't know, you didn't share much details on your hardware.
>> The hardware requires one I2S output line and one I2S input line + the
>> clock line.
>>
>> You say "Driver for I2S in Exynos 5 is already included in mainline
>> kernel." ... do you mean that all I need is a device tree file to enable
>> it ? If so, then can you please link me to an example device tree ... my
>> assumption is that this I2S device will show up in alsa once the device
>> tree is setup ?
> You'd probably need some codec stub, I'm not sure if it's possible to
> instantiate soundcard with only i2s and without a codec.
Thats fine, I can implement the codec stub. I guess I was originally 
contacting you (and others) to get some pointers on how to do that. Is 
there perhaps a codec stub for some very simple hardware (only I2S) 
which I could use as a reference ? Also would require an example dts 
file ... all for the Exynos.

thanks
Matt

> Regards
> Vasily
>
>>>> Can you give me advice - how to start ?
>>> Start with reading specs and try to understand how your implants work,
>>> then look at existing code and try to adapt it for your usage.
>>> Then clean it up and prepare for submitting into mainline.
>>>
>>>> thanks
>>>> Matt
>>> Regards,
>>> Vasily
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> Alsa-devel@alsa-project.org
> http://mailman.alsa-project.org/mailman/listinfo/alsa-devel

Re: I2S driver for implants

[Vasily Khoruzhick]

On 23 July 2014 21:08:11 Matt Flax wrote:

> > You'd probably need some codec stub, I'm not sure if it's possible to
> > instantiate soundcard with only i2s and without a codec.
> 
> Thats fine, I can implement the codec stub. I guess I was originally
> contacting you (and others) to get some pointers on how to do that. Is
> there perhaps a codec stub for some very simple hardware (only I2S)
> which I could use as a reference ?

You already have cpu dai (i2s), now you need codec dai (which is dummy).
Maybe I'm wrong, and you don't need a codec stub, I'm not an ASoC expert.

> Also would require an example dts
> file ... all for the Exynos.

Look for one in arch/arm/boot/dts?

> thanks
> Matt

Regards
Vasily