Atmel AT91 support in mainstream kernel 4.4

Atmel AT91 support in mainstream kernel 4.4

[Fernando AE]

Hello all,

I'd like to know if AT91 boards (more specifically AT91SAM9G20) is
well supported in mainstream Kernel 4.4.

In more details, I'm working in a project of bringing up Linux 4.4 in
a iMX6 based board, while trying to keep the same sources for our
legacy AT91 based board. So, I'm wondering if it's a good idea to take
Freescale's repo based on 4.4 as reference and compiling both for iMX
and AT91.

Thanks in advance for your advices,
Fernando A. E.

Atmel AT91 support in mainstream kernel 4.4

[Fabio Estevam]

Hi Fernando,

On Tue, Aug 21, 2018 at 9:10 AM, Fernando AE <fernando.ae2017@gmail.com> wrote:
> Hello all,
>
> I'd like to know if AT91 boards (more specifically AT91SAM9G20) is
> well supported in mainstream Kernel 4.4.
>
> In more details, I'm working in a project of bringing up Linux 4.4 in
> a iMX6 based board, while trying to keep the same sources for our
> legacy AT91 based board. So, I'm wondering if it's a good idea to take
> Freescale's repo based on 4.4 as reference and compiling both for iMX
> and AT91.

There is no need to use the NXP provided kernel (there is no 4.4
kernel provided by NXP by the way - only 4.1 and 4.9).

You could use the latest mainline kernel instead for the two platforms.

Atmel AT91 support in mainstream kernel 4.4

[Willy Tarreau]

Hi,

On Tue, Aug 21, 2018 at 02:10:14PM +0200, Fernando AE wrote:
> Hello all,
> 
> I'd like to know if AT91 boards (more specifically AT91SAM9G20) is
> well supported in mainstream Kernel 4.4.
> 
> In more details, I'm working in a project of bringing up Linux 4.4 in
> a iMX6 based board, while trying to keep the same sources for our
> legacy AT91 based board. So, I'm wondering if it's a good idea to take
> Freescale's repo based on 4.4 as reference and compiling both for iMX
> and AT91.

FWIW I remember having been running an AT91 board (linuxstamp 2) on
2.6.35 with a single patch by then, the one needed to create the board.
Everything else used to work out of the box. I don't see why anything
would have regressed since then without anyone complaining loud, so I'd
be inclined to think it's well supported.

Regards,
Willy

Atmel AT91 support in mainstream kernel 4.4

[Alexander Dahl]

Hei hei,

Am Dienstag, 21. August 2018, 14:10:14 CEST schrieb Fernando AE:
> I'd like to know if AT91 boards (more specifically AT91SAM9G20) is
> well supported in mainstream Kernel 4.4.

In general from my experience: yes, very well.

In detail: we are using the external memory interface with some SRAM like 
device on an at91sam9g20 based board with special timings and I remember DT 
didn't support that fully until 4.12 IIRC, so depending on your hardware maybe 
you might need some tweaks on the DT side, but that should all be straight 
forward.

Maybe use some newer LTS kernel like 4.9 or 4.14?

> In more details, I'm working in a project of bringing up Linux 4.4 in
> a iMX6 based board, while trying to keep the same sources for our
> legacy AT91 based board. So, I'm wondering if it's a good idea to take
> Freescale's repo based on 4.4 as reference and compiling both for iMX
> and AT91.

AFAIK i.MX6 is also well supported in mainline, so I would also opt for using 
a recent vanilla kernel for both boards.

HTH & Greets
Alex

Atmel AT91 support in mainstream kernel 4.4

[Alexandre Belloni]

Hi,

On 21/08/2018 14:30:47+0200, Willy Tarreau wrote:
> Hi,
> 
> On Tue, Aug 21, 2018 at 02:10:14PM +0200, Fernando AE wrote:
> > Hello all,
> > 
> > I'd like to know if AT91 boards (more specifically AT91SAM9G20) is
> > well supported in mainstream Kernel 4.4.
> > 
> > In more details, I'm working in a project of bringing up Linux 4.4 in
> > a iMX6 based board, while trying to keep the same sources for our
> > legacy AT91 based board. So, I'm wondering if it's a good idea to take
> > Freescale's repo based on 4.4 as reference and compiling both for iMX
> > and AT91.
> 
> FWIW I remember having been running an AT91 board (linuxstamp 2) on
> 2.6.35 with a single patch by then, the one needed to create the board.
> Everything else used to work out of the box. I don't see why anything
> would have regressed since then without anyone complaining loud, so I'd
> be inclined to think it's well supported.
> 

I confirm we don't have any out of tree patch for the at91sam9g20 so you
will get the best support there is using a mainline kernel.

-- 
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com