Re: [PATCH 0/7] towards QE support on ARM

[Rasmus Villemoes]

On 18/10/2019 22.16, Leo Li wrote:
> 
>>
>> There have been several attempts in the past few years to allow building the
>> QUICC engine drivers for platforms other than PPC. This is (the beginning of)
>> yet another attempt. I hope I can get someone to pick up these relatively
>> trivial patches (I _think_ they shouldn't change functionality at all), and then
>> I'll continue slowly working towards removing the PPC32 dependency for
>> CONFIG_QUICC_ENGINE.
> 
> Hi Rasmus,
> 
> I don't fully understand the motivation of this work.  As far as I know the QUICC ENGINE is only used on PowerPC based SoCs. 

Hm, you're not the Leo Li that participated in this thread
<https://lore.kernel.org/lkml/AM3PR04MB11857AE8D2B0BE56121B97D391C90@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/T/#u>?


 Can you give an example on how is it used on ARM system?

LS1021A, for example, which is the one I'm aiming for getting fully
supported in mainline.
<https://www.nxp.com/products/processors-and-microcontrollers/arm-processors/layerscape-communication-process/qoriq-layerscape-1021a-dual-core-communications-processor-with-lcd-controller:LS1021A>

The forks at https://github.com/qoriq-open-source/linux.git have various
degrees of support (grep for commits saying stuff like "remove PPCisms"
- some versions can be found on
<https://lore.kernel.org/lkml/?q=remove+ppcisms>). Our current kernel is
based on commits from the now-vanished 4.1 branch, and unfortunately at
least the 4.14 branch (LSDK-18.06-V4.14) trivially doesn't build on ARM,
despite the PPC32 dependency having been removed from CONFIG_QUICC_ENGINE.

>>
>> Tested on an MPC8309-derived board.
> 
> MPC8309 is also PPC based.

True, of course. This is just some first few steps, and I'm not claiming
that this is sufficient to make the QE drivers build on ARM yet. But I
have a customer with both mpc8309-based and ls1021a-based platforms, and
they want to run the same, as-close-to-mainline-as-possible, kernel on
both. So I will take a piecemeal approach, and try to make sure I don't
break the ppc boards in the process (just building and booting one board
is of course not sufficient, but better than nothing). Once I get to
actually build some of the QE drivers for ARM, I'll of course also test
them.

Rasmus