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

quoted

On Mon, Oct 22, 2019 at 6:11 AM Leo Li wrote
-----Original Message-----
From: Li Yang <redacted>
Sent: 2019年10月22日 6:11
To: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Timur Tabi <timur@kernel.org>; Greg Kroah-Hartman
[off-list ref]; linux-kernel@vger.kernel.org;
linux-serial@vger.kernel.org; Jiri Slaby [off-list ref];
linuxppc-dev@lists.ozlabs.org; linux-arm-kernel@lists.infradead.org; Qiang
Zhao [off-list ref]
Subject: Re: [PATCH 0/7] towards QE support on ARM

On Mon, Oct 21, 2019 at 3:46 AM Rasmus Villemoes
[off-list ref] wrote:
On 18/10/2019 23.52, Li Yang wrote:
On Fri, Oct 18, 2019 at 3:54 PM Rasmus Villemoes
[off-list ref] wrote:
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://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.ke
rnel.org%2Flkml%2FAM3PR04MB11857AE8D2B0BE56121B97D391C90%40A
M3PR04MB1185.eurprd04.prod.outlook.com%2FT%2F%23u&amp;data=02%7
C01%7Cqiang.zhao%40nxp.com%7C1ba8c50c2db14b22bef608d756739d82%
7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C6370729268771788
75&amp;sdata=k4zM75OczXwZF%2Br9ec4RxiVR2a%2F8GhSZmK70JYddIck%3
D&amp;reserved=0>?
Oops, I totally forgot about this discussion which is just three
years ago.  :)  The QE-HDLC on LS1021a is kind of a special case.

 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://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2F
www.nxp.com%2Fproducts%2Fprocessors-and-microcontrollers%2Farm-proc
essors%2Flayerscape-communication-process%2Fqoriq-layerscape-1021a-
dual-core-communications-processor-with-lcd-controller%3ALS1021A&am
p;data=02%7C01%7Cqiang.zhao%40nxp.com%7C1ba8c50c2db14b22bef608d
7567
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771788
75&amp;sdata=vqPYSZqEv6vCEIxJshLuA4gngh9J4IsFAQrTwJKMjm4%3D&amp;r
es
erved=0>

The forks at
https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.
com%2Fqoriq-open-source%2Flinux.git&amp;data=02%7C01%7Cqiang.zhao%
40nxp.com%7C1ba8c50c2db14b22bef608d756739d82%7C686ea1d3bc2b4c6
fa92cd99c5c301635%7C0%7C0%7C637072926877178875&amp;sdata=v4eG
4KqGTWQkQHp%2FYg2OHCKITLWaOgH64JYpY%2B1LilA%3D&amp;reserved=0
have various degrees of support (grep for commits saying stuff like "remove
PPCisms"
- some versions can be found on
<https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2F
lore.kernel.org%2Flkml%2F%3Fq%3Dremove%2Bppcisms&amp;data=02%7C0
1%7
Cqiang.zhao%40nxp.com%7C1ba8c50c2db14b22bef608d756739d82%7C686e
a1d3
bc2b4c6fa92cd99c5c301635%7C0%7C0%7C637072926877178875&amp;sdat
a=i2WdKNHLV68a1mTOMQ%2FoMr0y5ee8edS07xq61M8%2BvPU%3D&amp;r
eserved=0>). 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.
Can you try the 4.14 branch from a newer LSDK release?  LS1021a
should be supported platform on LSDK.  If it is broken, something is
wrong.
What newer release? LSDK-18.06-V4.14 is the latest -V4.14 tag at
https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgith
ub.com%2Fqoriq-open-source%2Flinux.git&amp;data=02%7C01%7Cqiang.zha
o%4
0nxp.com%7C1ba8c50c2db14b22bef608d756739d82%7C686ea1d3bc2b4c6f
a92cd99c
5c301635%7C0%7C0%7C637072926877188868&amp;sdata=vdm4qPoTzfIpXL
mRrv17EW
noxG3n91qELMGqvRh9we4%3D&amp;reserved=0, and identical to the
That tree has been abandoned for a while, we probably should state that in the
github.  The latest tree can be found at
https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fsource.
codeaurora.org%2Fexternal%2Fqoriq%2Fqoriq-components%2Flinux%2F&amp
;data=02%7C01%7Cqiang.zhao%40nxp.com%7C1ba8c50c2db14b22bef608d7
56739d82%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C6370729
26877188868&amp;sdata=NooBFUWnceTG2OF24pCuP0AYgKfr0Df%2BtrcCY6
X6Dog%3D&amp;reserved=0

linux-4.14 branch. And despite commit 4c33e2d0576b removing the PPC32
dependency from QUICC_ENGINE, it clearly hasn't been built on arm,
since back around v4.12, mainline's qe.c grew a call to pvr_version_is
which is ppc-only. So from that I sort of assumed that NXP had dropped
trying to support the LS1021A even in their own kernels.

In any case, we have zero interest in running an NXP kernel. Maybe I
should clarify what I meant by "based on commits from" above: We're
currently running a mainline 4.14 kernel on LS1021A, with a few
patches inspired from the NXP 4.1 branch applied on top - but also
with some manual fixes for e.g. the pvr_version_is() issue. Now we
want to move that to a 4.19-based kernel (so that it aligns with our
MPC8309 platform).

We also provide 4.19 based kernel in the codeaurora repo.  I think it will be
helpful to reuse patches there if you want to make your own tree.

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.
Understood.  Zhao Qiang also maintains some patches similar to your
patchset and I think they are tested on ARM.  But the review of
these patches from last submission didn't finish.  It looks like
your patches are better divided but not really verified on ARM.
Zhao Qiang's patches are tested but maybe need some final touch for
cleaning up.  I will let you guys decide what is the best approach
to make this upstreamed.
Yes, as I said, I wanted to try a fresh approach since Zhao Qiang's
patches seemed to be getting nowhere. Splitting the patches into
smaller pieces is definitely part of that - for example, the
completely trivial whitespace fix in patch 1 is to make sure the later
coccinelle generated patch is precisely that (i.e., a later respin can
just rerun the coccinelle script, with zero manual fixups). I also
want to avoid mixing the ppcism cleanups with other things (e.g.
replacing some
of_get_property() by of_property_read_u32()). And the "testing on ARM"
part comes once I get to actually building on ARM. But there's not
much point doing all that unless there's some indication that this can
be applied to some tree that actually feeds into Linus', which is why
I started with a few trivial patches and precisely to start this discussion.
Right.  I'm really interested in getting this applied to my tree and make it
upstream.  Zhao Qiang, can you help to review Rasmus's patches and
comment?
As you know, I maintained a similar patchset removing PPC, and someone told me qe_ic should moved into drivers/irqchip/.
I also thought qe_ic is a interrupt control driver, should be moved into dir irqchip.

Regards,
Qiang
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