Hello Kevin,

On Tue, Nov 25, 2014 at 8:50 AM, Kevin Hilman [off-list ref] wrote:

On Mon, Nov 24, 2014 at 5:50 PM, Kukjin Kim [off-list ref] wrote:

quoted

Olof Johansson wrote:

quoted

On Mon, Nov 24, 2014 at 5:37 PM, Olof Johansson [off-list ref] wrote:

quoted

On Mon, Nov 24, 2014 at 5:35 PM, Kevin Hilman [off-list ref] wrote:

quoted

On Mon, Nov 24, 2014 at 4:25 PM, Olof Johansson [off-list ref] wrote:

quoted

On Mon, Nov 24, 2014 at 11:51 AM, Kevin Hilman [off-list ref] wrote:

quoted

Kukjin,

On Mon, Nov 10, 2014 at 11:35 AM, Kevin Hilman [off-list ref] wrote:

quoted

Kukjin Kim [off-list ref] writes:

quoted

Kevin Hilman wrote:

quoted

From: Kevin Hilman <redacted>

The option CONFIG_EXYNOS5420_MCPM is causing imprecise external aborts
during boot testing, causing various userspace startup failures.

Disable until it has gotten more testing.

Cc: Kukjin Kim <redacted>,
Cc: Javier Martinez Canillas <redacted>,
Cc: Sachin Kamat <redacted>,
Cc: Doug Anderson <dianders@chromium.org>,
Cc: Bartlomiej Zolnierkiewicz <redacted>,
Cc: Krzysztof Kozlowski <redacted>,
Cc: Tushar Behera <redacted>,
Cc: stable at vger.kernel.org # v3.17+
Signed-off-by: Kevin Hilman <redacted>
---
This has been reported by a few people[1], but not investigated or fixed, so it's
time to disable this feature until it can be fixed.

Hi Kevin,

Yeah I agree with your opinion.

But as you can see my tree, I've queued regarding mcpm patches for 3.19 will
be shown in -next in this weekend.

Which of the recently queued patches are expected to address the
imprecise abort issue?  I'd be happy to test them out.

Exynos5 MCPM is still broken in linux-next and still causing an imprecise abort.

What is the status of $SUBJECT patch?

quoted

quoted

Anyway let me apply this into -fixes and
then let's enable after test its functionality in -next in a couple of days.

Yes, I think this needs to be applied until these aborts are understood
and fixed.

Is anyone at Samsung actually looking into these MCPM issues?

Hi Kevin,

What hardware are you having problems with? 5420 or 5422/5800?

Yes.  :)

exynos5420-arndale-octa:
http://storage.armcloud.us/kernel-ci/mainline/v3.18-rc6/arm-exynos_defconfig/boot-exynos5420-

arndale-octa.html

quoted

quoted

exynos5422-odroid-xu3:
http://storage.armcloud.us/kernel-ci/mainline/v3.18-rc6/arm-exynos_defconfig/boot-exynos5422-

odroid-xu3.html

quoted

quoted

My boot tests seem to pass fine because I have such a minimal
userspace, but Tyler Baker reported that with a "real" userspace, he
can't boot to a shell:

  http://lists.infradead.org/pipermail/linux-arm-kernel/2014-September/286203.html

Hmm...his report was in Sep...I think it should be fine with current -next?

No, it is still broken in linux-next (as I stated above.)

Moreover, earlier in this thread you mentioned you were merging some
MCPM patches that should address this, but did not respond when I
asked which patches you thing should address this issue

quoted

To be honest, since I don't have the exynos5420 arndale, chromebook...but smdk
which has different bootloader, I couldn't test it...I'll try to make a test
farm like you guys...

Do you have some colleagues with any other 542x hardware?  I had
assumed that linux-next was being better tested on the publicaly
available, and widely available boards like odroid-xu3 and
Chromebook2, but I've come to realize the hard way that that is not

Are you seeing this on Chromebook2 (Peach-Pi 5800) too ?

the case.  You mention your board has a different bootloader.  Do you
suspect there's a bootloader issue on these other platforms?  If so,
could you elaborate on possible fixes?  I'm more than willing to test
any proposed fixes, but I'm not familiar enough yet with these SoCs to
figure out the underlying issues alone.

Until you have a working board farm, you could start having a closer
look at the boot logs we're already producing.  Admittedly linux-next
broken in many ways besides this one for exynos currently, but it has
been having these imprecise aborts well before the other recent
issues.

Also, It's very possible that this issue is not even MCPM related at
all, and MCPM is just uncovering a previously hidden bug.  It would be
very helpful if people more familiar with this hardware and SoC would
investigate bug reports like these.

The 3 boards I have access to (SMDK5420, Chromebook Peach-Pi and
Chromebook Peach-Pit) work fine with MCPM enabled. I am not sure why
it is failing only on the above mentioned boards as there is nothing
specific to them in the MCPM back-end.

I assume that when you default to platsmp (on disabling MCPM), the
non-working boards boot all cores upto userspace without any issues ?

Based on the timeline (problems started about 2.5 months back), there
have only been a couple of changes in the 5420 MCPM back-end. Could
you revert the following commits and check if things improve.

20fe6f9 ARM: EXYNOS: Support cluster power off on exynos5420/5800
fbb0499 ARM: 8083/1: exynos: activate the CCI on boot CPU/cluster
using the MCPM loopback

These might not revert cleanly, so instead of the above you could also
comment the following 2 lines:

diff --git a/arch/arm/mach-exynos/mcpm-exynos.c

b/arch/arm/mach-exynos/mcpm-exynos.c
index dc9a764..9a07188 100644

--- a/arch/arm/mach-exynos/mcpm-exynos.c
+++ b/arch/arm/mach-exynos/mcpm-exynos.c

@@ -152,7 +152,7 @@ static void exynos_power_down(void)
                exynos_cpu_power_down(cpunr);

                if (exynos_cluster_unused(cluster)) {
-                       exynos_cluster_power_down(cluster);
+                       //exynos_cluster_power_down(cluster);
                        last_man = true;
                }
        } else if (cpu_use_count[cpu][cluster] == 1) {

@@ -356,8 +356,8 @@ static int __init exynos_mcpm_init(void)
        ret = mcpm_platform_register(&exynos_power_ops);
        if (!ret)
                ret = mcpm_sync_init(exynos_pm_power_up_setup);
-       if (!ret)
-               ret = mcpm_loopback(exynos_cache_off); /* turn on the CCI */
+       //if (!ret)
+               //ret = mcpm_loopback(exynos_cache_off); /* turn on the CCI */
        if (ret) {
                iounmap(ns_sram_base_addr);
                return ret;

If you still get aborts then I suspect that the problem is with the
bootloader configuration but am not sure. I am OK with disabling
5420_MCPM in the default configuration in such a case. This would
however mean that S2R also stops working by default on 5420.

Regards,
Abhilash

Kevin

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel at lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel