i.MX51 kernel trees: Where to start?

i.MX51 kernel trees: Where to start?

[David Jander]

Hi all,

I just subscribed to this list, in the hope that I have picked the right place 
to ask questions about linux kernel development for the Freescale i.MX51 SoC. 
If there are better/other places to be for that, I'd be very happy to know.

We are busy designing a new board based on the i.MX51 SoC, that will be 
running linux. This is the first ARM-linux development we are doing, after a 
few powerpc-linux developments.

To aid in design decision-making, we decided to purchase a MX51EVK board and 
investigate the state of linux/bsp/drivers for that platform, so here I am 
with quite a lot of newbie questions and the hope to get some of them answered 
here:

Please forgive me if I am asking something that has been discussed before. I 
have looked at the archives of this list, but did not find good answers.

1.- What's the most recommended (git-) tree to start from doing BSP 
development?
Right now, I am playing with sources downloaded from freescale directly, and 
AFAICS this is quite similar to the "tracking-fsl-imx_2.6.31" branch from denx 
git:

http://git.denx.de/?p=linux-2.6-denx.git;a=shortlog;h=refs/heads/tracking-fsl-
imx_2.6.31

Is this indeed the best place to start? What other trees are there, and how 
can I get an impression of the state of each one? How far are effords for 
mainline inclusion of the freescale patches?

2.- Using this kernel, I notice the touchscreen driver, (mxc_ts.c) not working 
correctly. It looks like it works for a few seconds after boot, and then 
starts delaying samples very much, to the point that it is unusable. Is this a 
known problem? Is there someone working on this? Should I use another driver?

Also, at least libts does not recognize touches as clicks, but merely updates 
the touch coordinates. I have yet to check which kinds of events are generated 
exactly, but it doesn't seem to be correct.


3.- What about the android patches? Is there someone actively working on 
Android on the i.MX51? What's the state of the Android patches from Freescale? 
Are they useable/combineable with current "normal" kernel trees?
We don't have plans currently on using Android, but it seems at least feasible 
that one of our clients might start asking for it....


Best regards,

-- 
David Jander
Protonic Holland.

i.MX51 kernel trees: Where to start?

[Baruch Siach]

Hi David,

On Wed, Jul 07, 2010 at 02:08:50PM +0200, David Jander wrote:
> 1.- What's the most recommended (git-) tree to start from doing BSP 
> development?
> Right now, I am playing with sources downloaded from freescale directly, and 
> AFAICS this is quite similar to the "tracking-fsl-imx_2.6.31" branch from denx 
> git:
> 
> http://git.denx.de/?p=linux-2.6-denx.git;a=shortlog;h=refs/heads/tracking-fsl-
> imx_2.6.31
> 
> Is this indeed the best place to start?

If you want to go with the mainline kernel then the place where i.MX 
development is happening is 
http://git.pengutronix.de/?p=imx/linux-2.6.git;a=summary

> What other trees are there, and how can I get an impression of the state of 
> each one?  How far are effords for mainline inclusion of the freescale 
> patches?

Freescale are doing very little to push their work for mainline inclusion.  
Amit Kucheria from Canonical/Linaro has been doing some work on the i.MX5 
front. This work is in the mainline kernels since 2.6.34.

> 2.- Using this kernel, I notice the touchscreen driver, (mxc_ts.c) not 
> working correctly. It looks like it works for a few seconds after boot, and 
> then starts delaying samples very much, to the point that it is unusable. Is 
> this a known problem? Is there someone working on this? Should I use another 
> driver?

This driver is not in the mainline kernel, so the help you may get from kernel 
developers is limited. In any case, questions about the input subsystem should 
go to the linux-input mailing list (linux-input at vger.kernel.org).

baruch

-- 
                                                     ~. .~   Tk Open Systems
=}------------------------------------------------ooO--U--Ooo------------{=
   - baruch at tkos.co.il - tel: +972.2.679.5364, http://www.tkos.co.il -

i.MX51 kernel trees: Where to start?

[David Jander]

Hi Baruch,

Thanks a lot for your reply.

On Thursday 08 July 2010 07:44:36 am Baruch Siach wrote:
> If you want to go with the mainline kernel then the place where i.MX
> development is happening is
> http://git.pengutronix.de/?p=imx/linux-2.6.git;a=summary

Is there a way of finding out exactly which peripherals of the i.MX51 are 
currently supported in this tree?
The master seems almost 2 months old, is there no ongoing porting work 
anymore, or is it all going into "for-next"?

> > What other trees are there, and how can I get an impression of the state
> > of each one?  How far are effords for mainline inclusion of the freescale
> > patches?
> 
> Freescale are doing very little to push their work for mainline inclusion.

That doesn't surprise me anymore, although I get the impression that they have 
learned at least a little bit form past lessons, since they are now at least 
"using" git ;-)

> Amit Kucheria from Canonical/Linaro has been doing some work on the i.MX5
> front. This work is in the mainline kernels since 2.6.34.

Sounds great... I'll need to figure out in what state the drivers for each 
peripheral are. Any hint other than just trying out?

> > 2.- Using this kernel, I notice the touchscreen driver, (mxc_ts.c) not
> > working correctly. It looks like it works for a few seconds after boot,
> > and then starts delaying samples very much, to the point that it is
> > unusable. Is this a known problem? Is there someone working on this?
> > Should I use another driver?
> 
> This driver is not in the mainline kernel, so the help you may get from
>  kernel developers is limited. In any case, questions about the input
>  subsystem should go to the linux-input mailing list
>  (linux-input at vger.kernel.org).

Thanks for the tip. If I get serious plans in porting that driver, I'll 
contact that list.

Best regards,

-- 
David Jander
Protonic Holland.

i.MX51 kernel trees: Where to start?

[Baruch Siach]

Hi David,

On Thu, Jul 08, 2010 at 09:28:36AM +0200, David Jander wrote:
> On Thursday 08 July 2010 07:44:36 am Baruch Siach wrote:
> > If you want to go with the mainline kernel then the place where i.MX
> > development is happening is
> > http://git.pengutronix.de/?p=imx/linux-2.6.git;a=summary
> 
> Is there a way of finding out exactly which peripherals of the i.MX51 are 
> currently supported in this tree?
> The master seems almost 2 months old, is there no ongoing porting work 
> anymore, or is it all going into "for-next"?

The for-next branch contains changes intended to go upstream in the next merge 
window. So, yes, that's where you find the new stuff.

[snip]

> > Amit Kucheria from Canonical/Linaro has been doing some work on the i.MX5
> > front. This work is in the mainline kernels since 2.6.34.
> 
> Sounds great... I'll need to figure out in what state the drivers for each 
> peripheral are. Any hint other than just trying out?

I guess that some of the i.MX51 peripherals are either identical or very close 
to those found in earlier i.MX chips, which already have drives in the 
mainline kernel. The only sure way to know which one works is to look at the 
chip Reference Manual, compare to the actual driver code, and test.

baruch

-- 
                                                     ~. .~   Tk Open Systems
=}------------------------------------------------ooO--U--Ooo------------{=
   - baruch at tkos.co.il - tel: +972.2.679.5364, http://www.tkos.co.il -