Q: I2C multiplexer support

Q: I2C multiplexer support

[Michael Lawnick]

Hi,

on my current project I'm now at the point to have to implement
multiplexer support. The last patch set from Rodolfo was for 2.6.29,
most parts seem to have been integrated already in 2.6.31
If I got it correctly the patch based on creating a mux folder with
i2c-mux.c as a core file and then additional mux layer files.
So my questions:
Rodolfo, do you have a more resent patch set?
Jean, what are your plans about multiplexer support, where do you see
open issues? Do you agree with current centralized layout or would you
prefer independent single files integrating all necessary parts and
residing in bus folder?

-- 
Kind Regards,

Michael

Re: Q: I2C multiplexer support

[Jean Delvare]

Hi Michael,

On Mon, 07 Dec 2009 10:07:54 +0100, Michael Lawnick wrote:
> on my current project I'm now at the point to have to implement
> multiplexer support. The last patch set from Rodolfo was for 2.6.29,

Correct.

> most parts seem to have been integrated already in 2.6.31

I don't think so, no. What went in (or more exactly, out of) i2c-core
in 2.6.31 was the removal of the legacy i2c binding model, along with
the cleanups that allowed. It should make multiplexing support easier
to add, but that's about it.

> If I got it correctly the patch based on creating a mux folder with
> i2c-mux.c as a core file and then additional mux layer files.
> So my questions:
> Rodolfo, do you have a more resent patch set?

I've been asking the same some weeks ago.

> Jean, what are your plans about multiplexer support, where do you see
> open issues?

In all honesty, I did not look at Rodolfo's code at all. When he sent
it originally, I didn't have the time, being in the middle of major
i2c-core changes and cleanups. After 2.6.31 was released, I finally had
the time to look into it. But as I knew the recent i2c-core changes
would require Rodolfo's patches to be rebased, I asked him to do that
first. But now it's apparently Rodolfo's time to be busy :( If you want
to help, you're welcome.

> Do you agree with current centralized layout or would you
> prefer independent single files integrating all necessary parts and
> residing in bus folder?

Not having looked at the current proposal, I can't really comment on
the design. But having a separate folder for mux drivers sounds sane at
first sight.

-- 
Jean Delvare

Re: Q: I2C multiplexer support

[Rodolfo Giometti]

On Mon, Dec 07, 2009 at 10:51:32AM +0100, Jean Delvare wrote:
> 
> In all honesty, I did not look at Rodolfo's code at all. When he sent
> it originally, I didn't have the time, being in the middle of major
> i2c-core changes and cleanups. After 2.6.31 was released, I finally had
> the time to look into it. But as I knew the recent i2c-core changes
> would require Rodolfo's patches to be rebased, I asked him to do that
> first. But now it's apparently Rodolfo's time to be busy :( If you want
> to help, you're welcome.

I should have some spare time during december... however I cannot test
the code anymore due lack of hardware. :'(

Please, coordinate ourself and try to finish this job!

Ciao,

Rodolfo

-- 

GNU/Linux Solutions                  e-mail: giometti-AVVDYK/kqiJWk0Htik3J/w@public.gmane.org
Linux Device Driver                          giometti-k2GhghHVRtY@public.gmane.org
Embedded Systems                     phone:  +39 349 2432127
UNIX programming                     skype:  rodolfo.giometti
Freelance ICT Italia - Consulente ICT Italia - www.consulenti-ict.it

Re: Q: I2C multiplexer support

[Michael Lawnick]

Rodolfo Giometti said the following:
> On Mon, Dec 07, 2009 at 10:51:32AM +0100, Jean Delvare wrote:
>> 
>> In all honesty, I did not look at Rodolfo's code at all. When he sent
>> it originally, I didn't have the time, being in the middle of major
>> i2c-core changes and cleanups. After 2.6.31 was released, I finally had
>> the time to look into it. But as I knew the recent i2c-core changes
>> would require Rodolfo's patches to be rebased, I asked him to do that
>> first. But now it's apparently Rodolfo's time to be busy :( If you want
>> to help, you're welcome.
> 
> I should have some spare time during december... however I cannot test
> the code anymore due lack of hardware. :'(
>
I could make my H/W guys to do a little extra job, so I have a mux-tree
board based on PCA9544AD:

 ----mux--mux---------
      |
      +---mux---mux---
      |
      +---mux---------

So if you make a patch, I can give it a try. Until then I will try my
luck for my own.

-- 
Kind Regards,
Michael

Re: Q: I2C multiplexer support

[Jean Delvare]

On Mon, 7 Dec 2009 11:00:00 +0100, Rodolfo Giometti wrote:
> On Mon, Dec 07, 2009 at 10:51:32AM +0100, Jean Delvare wrote:
> > 
> > In all honesty, I did not look at Rodolfo's code at all. When he sent
> > it originally, I didn't have the time, being in the middle of major
> > i2c-core changes and cleanups. After 2.6.31 was released, I finally had
> > the time to look into it. But as I knew the recent i2c-core changes
> > would require Rodolfo's patches to be rebased, I asked him to do that
> > first. But now it's apparently Rodolfo's time to be busy :( If you want
> > to help, you're welcome.
> 
> I should have some spare time during december... however I cannot test
> the code anymore due lack of hardware. :'(

I don't have any hardware to test either, but I hope Michael does?

I am also considering adding some kind of multiplexing support to
i2c-stub, so that testing can be done without real hardware at hand.
Not sure what it would look like though, nor how much work would be
needed.

> Please, coordinate ourself and try to finish this job!

What is most needed now is to port your work on top of kernel 2.6.32
(or Linus' latest) so that the patches do apply and build again and can
get some testing. It is also easier for me to review patches and keep
track of them when they apply.

-- 
Jean Delvare

Re: Q: I2C multiplexer support

[Rodolfo Giometti]

On Mon, Dec 07, 2009 at 12:57:37PM +0100, Jean Delvare wrote:
> 
> What is most needed now is to port your work on top of kernel 2.6.32
> (or Linus' latest) so that the patches do apply and build again and can
> get some testing. It is also easier for me to review patches and keep
> track of them when they apply.

Ok, I'm going to do it in the next days. :)

Ciao,

Rodolfo

-- 

GNU/Linux Solutions                  e-mail: giometti-AVVDYK/kqiJWk0Htik3J/w@public.gmane.org
Linux Device Driver                          giometti-k2GhghHVRtY@public.gmane.org
Embedded Systems                     phone:  +39 349 2432127
UNIX programming                     skype:  rodolfo.giometti
Freelance ICT Italia - Consulente ICT Italia - www.consulenti-ict.it

Re: Q: I2C multiplexer support

[Rodolfo Giometti]

On Mon, Dec 07, 2009 at 10:07:54AM +0100, Michael Lawnick wrote:
> Hi,
> 
> on my current project I'm now at the point to have to implement
> multiplexer support. The last patch set from Rodolfo was for 2.6.29,
> most parts seem to have been integrated already in 2.6.31
> If I got it correctly the patch based on creating a mux folder with
> i2c-mux.c as a core file and then additional mux layer files.
> So my questions:
> Rodolfo, do you have a more resent patch set?

No.

> Jean, what are your plans about multiplexer support, where do you see
> open issues? Do you agree with current centralized layout or would you
> prefer independent single files integrating all necessary parts and
> residing in bus folder?

If Jean agree on my last rework I'm willing to do all whatever is
needed in order to finish this job and integrate this support into the
main line. :)

Ciao,

Rodolfo

-- 

GNU/Linux Solutions                  e-mail: giometti-AVVDYK/kqiJWk0Htik3J/w@public.gmane.org
Linux Device Driver                          giometti-k2GhghHVRtY@public.gmane.org
Embedded Systems                     phone:  +39 349 2432127
UNIX programming                     skype:  rodolfo.giometti
Freelance ICT Italia - Consulente ICT Italia - www.consulenti-ict.it

Re: Q: I2C multiplexer support

[Jean Delvare]

On Mon, 7 Dec 2009 10:56:24 +0100, Rodolfo Giometti wrote:
> On Mon, Dec 07, 2009 at 10:07:54AM +0100, Michael Lawnick wrote:
> > Hi,
> > 
> > on my current project I'm now at the point to have to implement
> > multiplexer support. The last patch set from Rodolfo was for 2.6.29,
> > most parts seem to have been integrated already in 2.6.31
> > If I got it correctly the patch based on creating a mux folder with
> > i2c-mux.c as a core file and then additional mux layer files.
> > So my questions:
> > Rodolfo, do you have a more resent patch set?
> 
> No.
> 
> > Jean, what are your plans about multiplexer support, where do you see
> > open issues? Do you agree with current centralized layout or would you
> > prefer independent single files integrating all necessary parts and
> > residing in bus folder?
> 
> If Jean agree on my last rework I'm willing to do all whatever is
> needed in order to finish this job and integrate this support into the
> main line. :)

I can't tell if I agree without reading the code, and I won't read the
code if the patches do not apply. But don't worry anyway: I do want to
add multiplexing support, so even if not in the exact form you're
proposing, your work will definitely be the starting point for whatever
we end up agreeing on. Which means that your forward porting work will
not be time wasted, whatever happens next.

Anyway I don't expect the forward porting to need too much work.

-- 
Jean Delvare