Upstream linux-omap kernel on Nokia N900?

Upstream linux-omap kernel on Nokia N900?

[Arnaud Ebalard]

Hi,

Nokia N900 is shipped to users with a 2.6.28 omap kernel. Many patches
for the hardware and various features have been pushed upstream by Nokia
developers and possibly others. Those are now available in current l-o
tree.

Nonetheless, many drivers and various features are still missing
upstream. Simply put, one cannot expect to run a current l-o kernel on
the device (and expect to get a GUI and/or make call with the device).

To get an idea of what it would take to achieve that, I started looking
at what is missing upstream, what is already there and what is currently
being pushed. I started putting some notes on this triage work and a set
of patches here:

  http://natisbad.org/N900/n900-current-linux-omap-kernel.html

If some among you are interested and/or have comments on the topic, they
are welcome. Among other things, I am worried about the OMAP 3430 GPU
code: if some people from TI can provide some advice on that aspect,
that would be great!

Cheers,

a+

Re: Upstream linux-omap kernel on Nokia N900?

[Felipe Balbi]

Hi,

On Mon, Apr 19, 2010 at 01:49:15PM +0200, ext Arnaud Ebalard wrote:
>Nokia N900 is shipped to users with a 2.6.28 omap kernel. Many patches
>for the hardware and various features have been pushed upstream by Nokia
>developers and possibly others. Those are now available in current l-o
>tree.
>
>Nonetheless, many drivers and various features are still missing
>upstream. Simply put, one cannot expect to run a current l-o kernel on
>the device (and expect to get a GUI and/or make call with the device).

tell me about it :-p

Thing is that it doesn't really depend only on Nokia to get those parts 
done. Well, we can get the kernel part done by just cleaning up and 
porting the 2.6.28 drivers to current mainline, but in case of e.g. SGX 
we still miss the xorg driver and I don't think that'll be released any 
time soon.

Another problem is that the bootloader believes it can pass all the 
obsoleted OMAP TAGs to kernel and the 2.6.28 kernel depends on those, 
maybe that can be worked around. I don't know whether kernel simply 
drops invalid TAGs or not...

Good work anyways... At least it's now documented ;-)

PS:

BTW, CBUS isn't really necessary for n900 and I have almost 40 patches 
cleaning that up pending in this mailing list :-p

-- 
balbi

Re: Upstream linux-omap kernel on Nokia N900?

[Roger Quadros]

Balbi Felipe (Nokia-D/Helsinki) wrote:
> Hi,
> 
> On Mon, Apr 19, 2010 at 01:49:15PM +0200, ext Arnaud Ebalard wrote:
>> Nokia N900 is shipped to users with a 2.6.28 omap kernel. Many patches
>> for the hardware and various features have been pushed upstream by Nokia
>> developers and possibly others. Those are now available in current l-o
>> tree.
>>
>> Nonetheless, many drivers and various features are still missing
>> upstream. Simply put, one cannot expect to run a current l-o kernel on
>> the device (and expect to get a GUI and/or make call with the device).
> 
> tell me about it :-p
> 
> Thing is that it doesn't really depend only on Nokia to get those parts 
> done. Well, we can get the kernel part done by just cleaning up and 
> porting the 2.6.28 drivers to current mainline, but in case of e.g. SGX 
> we still miss the xorg driver and I don't think that'll be released any 
> time soon.
> 
> Another problem is that the bootloader believes it can pass all the 
> obsoleted OMAP TAGs to kernel and the 2.6.28 kernel depends on those, 
> maybe that can be worked around. I don't know whether kernel simply 
> drops invalid TAGs or not...

Yes kernel simply drops unrecognized TAGs and just prints a warning message.

> 
> Good work anyways... At least it's now documented ;-)
> 
> PS:
> 
> BTW, CBUS isn't really necessary for n900 and I have almost 40 patches 
> cleaning that up pending in this mailing list :-p
> 

Re: Upstream linux-omap kernel on Nokia N900?

[Arnaud Ebalard]

Hi,

Felipe Balbi <felipe.balbi@nokia.com> writes:

> On Mon, Apr 19, 2010 at 01:49:15PM +0200, ext Arnaud Ebalard wrote:
>>Nokia N900 is shipped to users with a 2.6.28 omap kernel. Many patches
>>for the hardware and various features have been pushed upstream by Nokia
>>developers and possibly others. Those are now available in current l-o
>>tree.
>>
>>Nonetheless, many drivers and various features are still missing
>>upstream. Simply put, one cannot expect to run a current l-o kernel on
>>the device (and expect to get a GUI and/or make call with the device).
>
> tell me about it :-p
>
> Thing is that it doesn't really depend only on Nokia to get those
> parts done. Well, we can get the kernel part done by just cleaning up
> and porting the 2.6.28 drivers to current mainline, but in case of
> e.g. SGX we still miss the xorg driver and I don't think that'll be
> released any time soon.

I agree. I also spotted SGX code as the main obstacle and I started
wondering at how "kernel-independent" it was. IIRC, it is possible to
make it compile againt current l-o with only limited changes. Maybe TI
developers can provide some hints.

The other main obstacle was the code to interface with the phone stack
(SSI MacSAAB, CMT stuff). Felipe, do you know if someone @nokia has some
more recent version available which could be shared if there is good
news from TI on SGX aspect.

> Another problem is that the bootloader believes it can pass all the
> obsoleted OMAP TAGs to kernel and the 2.6.28 kernel depends on those,
> maybe that can be worked around. I don't know whether kernel simply
> drops invalid TAGs or not...

Well, with the first patches (simple update from the ones in official
kernel) in my set, I think that I managed to get getbootstate happy,
i.e. get /proc/bootreason available.

> Good work anyways... At least it's now documented ;-)

Thanks.

> PS:
>
> BTW, CBUS isn't really necessary for n900 and I have almost 40 patches
> cleaning that up pending in this mailing list :-p

yep, I kept it in my series file (cbus-support.patch) as uneeded.

Thanks for your work,

a+

Re: Upstream linux-omap kernel on Nokia N900?

[Felipe Balbi]

Hi,

On Mon, Apr 19, 2010 at 02:23:39PM +0200, ext Arnaud Ebalard wrote:
>The other main obstacle was the code to interface with the phone stack
>(SSI MacSAAB, CMT stuff). Felipe, do you know if someone @nokia has some
>more recent version available which could be shared if there is good
>news from TI on SGX aspect.

personally I really dislike the way the whole SSI were written but 
that's only my opinion. And I don't whether anyone would have other 
version of that. Maybe you can contact the original author which should 
be listed in the files' header.

-- 
balbi

Re: Upstream linux-omap kernel on Nokia N900?

[Arnaud Ebalard]

Felipe Balbi <felipe.balbi@nokia.com> writes:

> On Mon, Apr 19, 2010 at 02:23:39PM +0200, ext Arnaud Ebalard wrote:
>>The other main obstacle was the code to interface with the phone stack
>>(SSI MacSAAB, CMT stuff). Felipe, do you know if someone @nokia has some
>>more recent version available which could be shared if there is good
>>news from TI on SGX aspect.
>
> personally I really dislike the way the whole SSI were written but
> that's only my opinion. And I don't whether anyone would have other
> version of that. Maybe you can contact the original author which
> should be listed in the files' header.

Carlos Chinea (@nokia). I sent him an eamil two weeks ago but got no
response yet. I will wait a bit more (he may be busy) and take a look at
the code meanwhile.

Cheers,

a+

Re: Upstream linux-omap kernel on Nokia N900?

[Tony Lindgren]

* Roger Quadros <roger.quadros@nokia.com> [100419 05:06]:
> Balbi Felipe (Nokia-D/Helsinki) wrote:
> >Hi,
> >
> >On Mon, Apr 19, 2010 at 01:49:15PM +0200, ext Arnaud Ebalard wrote:
> >>Nokia N900 is shipped to users with a 2.6.28 omap kernel. Many patches
> >>for the hardware and various features have been pushed upstream by Nokia
> >>developers and possibly others. Those are now available in current l-o
> >>tree.
> >>
> >>Nonetheless, many drivers and various features are still missing
> >>upstream. Simply put, one cannot expect to run a current l-o kernel on
> >>the device (and expect to get a GUI and/or make call with the device).
> >
> >tell me about it :-p
> >
> >Thing is that it doesn't really depend only on Nokia to get those
> >parts done. Well, we can get the kernel part done by just cleaning
> >up and porting the 2.6.28 drivers to current mainline, but in case
> >of e.g. SGX we still miss the xorg driver and I don't think
> >that'll be released any time soon.
> >
> >Another problem is that the bootloader believes it can pass all
> >the obsoleted OMAP TAGs to kernel and the 2.6.28 kernel depends on
> >those, maybe that can be worked around. I don't know whether
> >kernel simply drops invalid TAGs or not...
> 
> Yes kernel simply drops unrecognized TAGs and just prints a warning message.

All the the custom tags should be replaced with platform_data.

If something is needed for revision detection of the board,
there is arm-linux common ATAG_REVISION.

However, also Maemo userspace depends on some things set by the
custom tags. As this is non-standard, we should not spend much
effort on that. Instead we should concentrate on making N900
work with any distro the standard Linux way.

So I recommend using kexec patched Maemo kernel, then boot the
new mainline kernel from Maemo kernel and mount root directly
on the eMMC.

As Maemo user space has some dependencies to the partition
layout, you need to keep the existing partition layout too.
In any case, I ended up resizing the eMMC partitions and using
/dev/mmcblk0p2 (mounted as /home in Maemo) as the new root
partition.

Cheers,

Tony

Re: Upstream linux-omap kernel on Nokia N900?

[Roger Quadros]

ext Tony Lindgren wrote:
> * Roger Quadros <roger.quadros@nokia.com> [100419 05:06]:
>> Balbi Felipe (Nokia-D/Helsinki) wrote:
>>> Hi,
>>>
>>> On Mon, Apr 19, 2010 at 01:49:15PM +0200, ext Arnaud Ebalard wrote:
>>>> Nokia N900 is shipped to users with a 2.6.28 omap kernel. Many patches
>>>> for the hardware and various features have been pushed upstream by Nokia
>>>> developers and possibly others. Those are now available in current l-o
>>>> tree.
>>>>
>>>> Nonetheless, many drivers and various features are still missing
>>>> upstream. Simply put, one cannot expect to run a current l-o kernel on
>>>> the device (and expect to get a GUI and/or make call with the device).
>>> tell me about it :-p
>>>
>>> Thing is that it doesn't really depend only on Nokia to get those
>>> parts done. Well, we can get the kernel part done by just cleaning
>>> up and porting the 2.6.28 drivers to current mainline, but in case
>>> of e.g. SGX we still miss the xorg driver and I don't think
>>> that'll be released any time soon.
>>>
>>> Another problem is that the bootloader believes it can pass all
>>> the obsoleted OMAP TAGs to kernel and the 2.6.28 kernel depends on
>>> those, maybe that can be worked around. I don't know whether
>>> kernel simply drops invalid TAGs or not...
>> Yes kernel simply drops unrecognized TAGs and just prints a warning message.
> 
> All the the custom tags should be replaced with platform_data.
> 
> If something is needed for revision detection of the board,
> there is arm-linux common ATAG_REVISION.
> 
> However, also Maemo userspace depends on some things set by the
> custom tags. As this is non-standard, we should not spend much
> effort on that. Instead we should concentrate on making N900
> work with any distro the standard Linux way.
> 
> So I recommend using kexec patched Maemo kernel, then boot the
> new mainline kernel from Maemo kernel and mount root directly
> on the eMMC.

FYI. kexec-tools will be available in maemo.org repo soon and you can also 
expect kexec patched kernel to be available.

Then we need a kexec helper utility that parses /proc/atags and feeds the 
necessary stuff on Command line for the new kernel.

So the ATAG Hacks will be unnecessary.

cheers,
-roger

Re: Upstream linux-omap kernel on Nokia N900?

[Ameya Palande]

On Tue, 2010-04-20 at 10:36 +0200, Quadros Roger (Nokia-D/Helsinki)
wrote:
> ext Tony Lindgren wrote:
> > * Roger Quadros <roger.quadros@nokia.com> [100419 05:06]:
> >> Balbi Felipe (Nokia-D/Helsinki) wrote:
> >>> Hi,
> >>>
> >>> On Mon, Apr 19, 2010 at 01:49:15PM +0200, ext Arnaud Ebalard wrote:
> >>>> Nokia N900 is shipped to users with a 2.6.28 omap kernel. Many patches
> >>>> for the hardware and various features have been pushed upstream by Nokia
> >>>> developers and possibly others. Those are now available in current l-o
> >>>> tree.
> >>>>
> >>>> Nonetheless, many drivers and various features are still missing
> >>>> upstream. Simply put, one cannot expect to run a current l-o kernel on
> >>>> the device (and expect to get a GUI and/or make call with the device).
> >>> tell me about it :-p
> >>>
> >>> Thing is that it doesn't really depend only on Nokia to get those
> >>> parts done. Well, we can get the kernel part done by just cleaning
> >>> up and porting the 2.6.28 drivers to current mainline, but in case
> >>> of e.g. SGX we still miss the xorg driver and I don't think
> >>> that'll be released any time soon.
> >>>
> >>> Another problem is that the bootloader believes it can pass all
> >>> the obsoleted OMAP TAGs to kernel and the 2.6.28 kernel depends on
> >>> those, maybe that can be worked around. I don't know whether
> >>> kernel simply drops invalid TAGs or not...
> >> Yes kernel simply drops unrecognized TAGs and just prints a warning message.
> > 
> > All the the custom tags should be replaced with platform_data.
> > 
> > If something is needed for revision detection of the board,
> > there is arm-linux common ATAG_REVISION.
> > 
> > However, also Maemo userspace depends on some things set by the
> > custom tags. As this is non-standard, we should not spend much
> > effort on that. Instead we should concentrate on making N900
> > work with any distro the standard Linux way.
> > 
> > So I recommend using kexec patched Maemo kernel, then boot the
> > new mainline kernel from Maemo kernel and mount root directly
> > on the eMMC.
> 
> FYI. kexec-tools will be available in maemo.org repo soon and you can also 
> expect kexec patched kernel to be available.

Everything related to kexec (kernel patches and user-space) on n900 is
documented here:
http://wiki.meego.com/ARM/Meego_kexec_install_on_N900

kexec-tools is already available from maemo-extras (testing) repository.

Cheers,
Ameya.

Re: Upstream linux-omap kernel on Nokia N900?

[Lauri Leukkunen]

On 19/04/10 21:51 +0200, ext Tony Lindgren wrote:
> * Roger Quadros <roger.quadros@nokia.com> [100419 05:06]:
> > Balbi Felipe (Nokia-D/Helsinki) wrote:
> > >Hi,
> > >
> > >On Mon, Apr 19, 2010 at 01:49:15PM +0200, ext Arnaud Ebalard wrote:
> > >>Nokia N900 is shipped to users with a 2.6.28 omap kernel. Many patches
> > >>for the hardware and various features have been pushed upstream by Nokia
> > >>developers and possibly others. Those are now available in current l-o
> > >>tree.
> > >>
> > >>Nonetheless, many drivers and various features are still missing
> > >>upstream. Simply put, one cannot expect to run a current l-o kernel on
> > >>the device (and expect to get a GUI and/or make call with the device).
> > >
> > >tell me about it :-p
> > >
> > >Thing is that it doesn't really depend only on Nokia to get those
> > >parts done. Well, we can get the kernel part done by just cleaning
> > >up and porting the 2.6.28 drivers to current mainline, but in case
> > >of e.g. SGX we still miss the xorg driver and I don't think
> > >that'll be released any time soon.
> > >
> > >Another problem is that the bootloader believes it can pass all
> > >the obsoleted OMAP TAGs to kernel and the 2.6.28 kernel depends on
> > >those, maybe that can be worked around. I don't know whether
> > >kernel simply drops invalid TAGs or not...
> > 
> > Yes kernel simply drops unrecognized TAGs and just prints a warning message.
> 
> All the the custom tags should be replaced with platform_data.
> 
> If something is needed for revision detection of the board,
> there is arm-linux common ATAG_REVISION.
> 
> However, also Maemo userspace depends on some things set by the
> custom tags. As this is non-standard, we should not spend much
> effort on that. Instead we should concentrate on making N900
> work with any distro the standard Linux way.
> 
> So I recommend using kexec patched Maemo kernel, then boot the
> new mainline kernel from Maemo kernel and mount root directly
> on the eMMC.
> 
> As Maemo user space has some dependencies to the partition
> layout, you need to keep the existing partition layout too.
> In any case, I ended up resizing the eMMC partitions and using
> /dev/mmcblk0p2 (mounted as /home in Maemo) as the new root
> partition.

Yup, I agree with Tony. I would much prefer to see real debian running on the
device over a somewhat patched-up Maemo with a newer kernel. The X.org server
can work without the SGX driver just fine, only the OMAP DSS needs to
function in order to get stuff on screen. What you might miss is the task
switcher, but as one prolific person has said, having to have a task
manager indicates failure ;P

/lauri