Re: [GIT PULL] ARM: SoC fixes

Re: [GIT PULL] ARM: SoC fixes

[Tony Lindgren]

* Olof Johansson <olof@lixom.net> [181107 09:28]:
> On Wed, Nov 7, 2018 at 9:17 AM Linus Torvalds
> <torvalds@linux-foundation.org> wrote:
> >
> > On Wed, Nov 7, 2018 at 9:10 AM Olof Johansson <olof@lixom.net> wrote:
> > >
> > > ARM: SoC fixes
> >
> > Pulled.
> >
> > > I was a bit too trigger happy to enable PREEMPT on multi_v7_defconfig,
> > > and it ended up regressing at least BeagleBone XM boards.
> >
> > Odd. Did it hit some "may_sleep()" test in a driver that is hidden by
> > preempt being off? Otherwise I don't see how/why preempt should fail
> > in a board-specific manner..
> 
> The board hangs early during boot and the usual way of collecting
> early console doesn't seem to work when attempted (I haven't tried
> personally).
> 
> It's one of the major non-SMP platforms covered by tests. I'd be
> surprised if it turns out to be truly _board_ specific (and rather
> specific to OMAP3), but we don't have enough data yet. Chances are it
> either shuffles some timing around or indeed hits a may_sleep() test
> somewhere.
> 
> (I just realized I might have missed to attribute Guillaume in the
> revert patch. Sorry about that).

Looks like we're missing the stdout-path for earlycon, maybe try
with the following patch? I can't find my Beagleboard-xm right now,
time to clean-up a bit I guess.

At least omap3-evm, logicpd-torpedo and n900 all boot with PREEMPT.

Regards,

Tony

8< ----------------------
>From tony Mon Sep 17 00:00:00 2001
From: Tony Lindgren <tony@atomide.com>
Date: Thu, 8 Nov 2018 07:43:28 -0800
Subject: [PATCH] ARM: dts: Add missing earlycon UART for Beagleboard

We can get early boot messages if CONFIG_SERIAL_EARLYCON=y is set, and
kernel commandline has debug earlycon. But we're missing the related dts
entry for Beagleboard.

Signed-off-by: Tony Lindgren <tony@atomide.com>
---

Note: Untested, I can't find my Beagleboard-XM right now..

---
 arch/arm/boot/dts/omap3-beagle.dts | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/arm/boot/dts/omap3-beagle.dts b/arch/arm/boot/dts/omap3-beagle.dts
--- a/arch/arm/boot/dts/omap3-beagle.dts
+++ b/arch/arm/boot/dts/omap3-beagle.dts
@@ -24,6 +24,10 @@
 		reg = <0x80000000 0x10000000>; /* 256 MB */
 	};
 
+	chosen {
+		stdout-path = &uart3;
+	};
+
 	aliases {
 		display0 = &dvi0;
 		display1 = &tv0;
-- 
2.19.1

Re: [GIT PULL] ARM: SoC fixes

[Olof Johansson]

On Thu, Nov 8, 2018 at 7:49 AM Tony Lindgren <tony@atomide.com> wrote:
>
> * Olof Johansson <olof@lixom.net> [181107 09:28]:
> > On Wed, Nov 7, 2018 at 9:17 AM Linus Torvalds
> > <torvalds@linux-foundation.org> wrote:
> > >
> > > On Wed, Nov 7, 2018 at 9:10 AM Olof Johansson <olof@lixom.net> wrote:
> > > >
> > > > ARM: SoC fixes
> > >
> > > Pulled.
> > >
> > > > I was a bit too trigger happy to enable PREEMPT on multi_v7_defconfig,
> > > > and it ended up regressing at least BeagleBone XM boards.
> > >
> > > Odd. Did it hit some "may_sleep()" test in a driver that is hidden by
> > > preempt being off? Otherwise I don't see how/why preempt should fail
> > > in a board-specific manner..
> >
> > The board hangs early during boot and the usual way of collecting
> > early console doesn't seem to work when attempted (I haven't tried
> > personally).
> >
> > It's one of the major non-SMP platforms covered by tests. I'd be
> > surprised if it turns out to be truly _board_ specific (and rather
> > specific to OMAP3), but we don't have enough data yet. Chances are it
> > either shuffles some timing around or indeed hits a may_sleep() test
> > somewhere.
> >
> > (I just realized I might have missed to attribute Guillaume in the
> > revert patch. Sorry about that).
>
> Looks like we're missing the stdout-path for earlycon, maybe try
> with the following patch? I can't find my Beagleboard-xm right now,
> time to clean-up a bit I guess.
>
> At least omap3-evm, logicpd-torpedo and n900 all boot with PREEMPT.

To follow up on this, it turned out to be an issue where the kernel
outgrew the location it was loaded to, and overwrite the device tree
on decompression. So, not a code issue.

It's a known fragile aspect on some of the u-boot setups, and
something I've been hit by myself on my farm a few times.

Still, for now we'll keep PREEMPT off until next merge window.


-Olof

Re: [GIT PULL] ARM: SoC fixes

[Corentin Labbe]

On Sat, Nov 10, 2018 at 10:09:19AM -0800, Olof Johansson wrote:
> On Thu, Nov 8, 2018 at 7:49 AM Tony Lindgren <tony@atomide.com> wrote:
> >
> > * Olof Johansson <olof@lixom.net> [181107 09:28]:
> > > On Wed, Nov 7, 2018 at 9:17 AM Linus Torvalds
> > > <torvalds@linux-foundation.org> wrote:
> > > >
> > > > On Wed, Nov 7, 2018 at 9:10 AM Olof Johansson <olof@lixom.net> wrote:
> > > > >
> > > > > ARM: SoC fixes
> > > >
> > > > Pulled.
> > > >
> > > > > I was a bit too trigger happy to enable PREEMPT on multi_v7_defconfig,
> > > > > and it ended up regressing at least BeagleBone XM boards.
> > > >
> > > > Odd. Did it hit some "may_sleep()" test in a driver that is hidden by
> > > > preempt being off? Otherwise I don't see how/why preempt should fail
> > > > in a board-specific manner..
> > >
> > > The board hangs early during boot and the usual way of collecting
> > > early console doesn't seem to work when attempted (I haven't tried
> > > personally).
> > >
> > > It's one of the major non-SMP platforms covered by tests. I'd be
> > > surprised if it turns out to be truly _board_ specific (and rather
> > > specific to OMAP3), but we don't have enough data yet. Chances are it
> > > either shuffles some timing around or indeed hits a may_sleep() test
> > > somewhere.
> > >
> > > (I just realized I might have missed to attribute Guillaume in the
> > > revert patch. Sorry about that).
> >
> > Looks like we're missing the stdout-path for earlycon, maybe try
> > with the following patch? I can't find my Beagleboard-xm right now,
> > time to clean-up a bit I guess.
> >
> > At least omap3-evm, logicpd-torpedo and n900 all boot with PREEMPT.
> 
> To follow up on this, it turned out to be an issue where the kernel
> outgrew the location it was loaded to, and overwrite the device tree
> on decompression. So, not a code issue.
> 
> It's a known fragile aspect on some of the u-boot setups, and
> something I've been hit by myself on my farm a few times.
> 
> Still, for now we'll keep PREEMPT off until next merge window.
> 

Hello

Note that CONFIG_PREEMPT cause some errors also on sun8i-a83t-bananapi-m3
Already reported https://lkml.org/lkml/2017/12/29/139

Regards

Re: [GIT PULL] ARM: SoC fixes

[Tony Lindgren]

* Corentin Labbe <clabbe.montjoie@gmail.com> [181112 06:13]:
> On Sat, Nov 10, 2018 at 10:09:19AM -0800, Olof Johansson wrote:
> > On Thu, Nov 8, 2018 at 7:49 AM Tony Lindgren <tony@atomide.com> wrote:
> > >
> > > * Olof Johansson <olof@lixom.net> [181107 09:28]:
> > > > On Wed, Nov 7, 2018 at 9:17 AM Linus Torvalds
> > > > <torvalds@linux-foundation.org> wrote:
> > > > >
> > > > > On Wed, Nov 7, 2018 at 9:10 AM Olof Johansson <olof@lixom.net> wrote:
> > > > > >
> > > > > > ARM: SoC fixes
> > > > >
> > > > > Pulled.
> > > > >
> > > > > > I was a bit too trigger happy to enable PREEMPT on multi_v7_defconfig,
> > > > > > and it ended up regressing at least BeagleBone XM boards.
> > > > >
> > > > > Odd. Did it hit some "may_sleep()" test in a driver that is hidden by
> > > > > preempt being off? Otherwise I don't see how/why preempt should fail
> > > > > in a board-specific manner..
> > > >
> > > > The board hangs early during boot and the usual way of collecting
> > > > early console doesn't seem to work when attempted (I haven't tried
> > > > personally).
> > > >
> > > > It's one of the major non-SMP platforms covered by tests. I'd be
> > > > surprised if it turns out to be truly _board_ specific (and rather
> > > > specific to OMAP3), but we don't have enough data yet. Chances are it
> > > > either shuffles some timing around or indeed hits a may_sleep() test
> > > > somewhere.
> > > >
> > > > (I just realized I might have missed to attribute Guillaume in the
> > > > revert patch. Sorry about that).
> > >
> > > Looks like we're missing the stdout-path for earlycon, maybe try
> > > with the following patch? I can't find my Beagleboard-xm right now,
> > > time to clean-up a bit I guess.
> > >
> > > At least omap3-evm, logicpd-torpedo and n900 all boot with PREEMPT.
> > 
> > To follow up on this, it turned out to be an issue where the kernel
> > outgrew the location it was loaded to, and overwrite the device tree
> > on decompression. So, not a code issue.
> > 
> > It's a known fragile aspect on some of the u-boot setups, and
> > something I've been hit by myself on my farm a few times.
> > 
> > Still, for now we'll keep PREEMPT off until next merge window.
> > 
> 
> Hello
> 
> Note that CONFIG_PREEMPT cause some errors also on sun8i-a83t-bananapi-m3
> Already reported https://lkml.org/lkml/2017/12/29/139

Also thread "[PATCH v1 1/5] drivercore: Revert "deferral race condition fix"
is reverting commit 58b116bce136 ("drivercore: deferral race condition fix")
which has CONFIG_PREEMPT mentioned in the log. So more testing is
probably needed in Linux next before enabling CONFIG_PREEMPT again.

Regards,

Tony