Odroid-C2 solid green screen on "echo c > /proc/sysrq-trigger" on Arch 4.16/4.17rc6

Neil Armstrong narmstrong at baylibre.com
Sat May 26 01:33:02 PDT 2018


Hi,

I'm sorry to disappoint you, but with the HW watchdog, we *can't* execute any code from Linux when the watchdoog resets the system.
We could eventually add some code in U-Boot to disable the HDMI output, but U-boot is not the first code executed, you will still see the green screen.
You may need to contact Hardkernel to see if they can update the BL* binaries to include such reset.

Neil

On 26/05/2018 05:49, Swabey, Matthew A wrote:
> Can also confirm green screen on watchdog reboot from "echo c > /proc/sysrq-trigger" for Armbian 5.44 with linux-u-boot-odroidc2-next version 2018.03.
> 
> This is in addition to the Armbian bug where shutdown -r now doesn’t reboot the system, just either freezes or powers down. Supposed to be fixed on 2018.03 but not working for me.
> 
> Matthew
> 
> Dr. Matthew Swabey - Director 
> Bechtel Innovation Design Center - Purdue University
> room: BIDC 225      phone: +1-765-494-8655
> 
> -----Original Message-----
> From: linux-amlogic [mailto:linux-amlogic-bounces at lists.infradead.org] On Behalf Of Swabey, Matthew A
> Sent: Friday, May 25, 2018 10:37 PM
> To: Tony McKahan <tonymckahan at gmail.com>; Neil Armstrong <narmstrong at baylibre.com>
> Cc: linux-amlogic at lists.infradead.org
> Subject: RE: Odroid-C2 solid green screen on "echo c > /proc/sysrq-trigger" on Arch 4.16/4.17rc6
> 
> I just had a look at the Arch linux PKGBUILD for the uboot package I am using, and it is mainline 2017.07. So I am using the mainline uboot, just a bit older.
> 
> I’ll give Armbian a try – is it the distro wit1h the most development so far? (Other than the 3.14.x releases which I would prefer not to use for now).
> 
> Matthew
> 
> Dr. Matthew Swabey - Director
> Bechtel Innovation Design Center - Purdue University
> room: BIDC 225      phone: +1-765-494-8655
> 
> From: Tony McKahan [mailto:tonymckahan at gmail.com]
> Sent: Friday, May 25, 2018 3:46 PM
> To: Neil Armstrong <narmstrong at baylibre.com>
> Cc: Swabey, Matthew A <maswabey at purdue.edu>; linux-amlogic at lists.infradead.org
> Subject: Re: Odroid-C2 solid green screen on "echo c > /proc/sysrq-trigger" on Arch 4.16/4.17rc6
> 
> Hello Neil, Matt,
> 
> Change to 2018.03 is in Armbian's development branch, just waiting to be rolled into the master.  I don't have this particular board for testing, but it should be updated soon.
> 
> On Fri, May 25, 2018, 3:57 AM Neil Armstrong <mailto:narmstrong at baylibre.com> wrote:
> Hi,
> 
> On 25/05/2018 04:19, Swabey, Matthew A wrote:
>> Odroid-C2 solid green screen on echo c > /proc/sysrq-trigger on Arch 
>> Linux mainline 4.16/4.17rc6 Using lightdm on xorg fb. No mali, utgard or odroid specific framebuffers. However it seems to happen on them too.
>>
>> Steps to reproduce:
>> 1. Boot
>> 2. Echo c > /proc/sysrq-trigger with watchdog set. Or trigger the watchdog another way, i.e. watchdogd or system.
>> 3. Watchdog causes reboot
>> 4. Boots with screen solid green, see photo here: 
>> https://photos.app.goo.gl/9VyiweNAIMD07VSM2
>>        a. No error messages visible, see attached log file bundles 
>> containing dmesg, journalctl, package list, Xorg.0.log
>>        b. Linux-aarch64 is 4.16
>>        c. Linux-aarch64-rc is 4.17rc6
>> 5. Reboot - screen back to normal and working
> Well, since screen goes back to normal means there is no bug on the kernel side.
> 
> This is caused by Amlogic's U-Boot.
> The HW watchdog does a complete SoC reset, we cannot execute any code from kernel when the watchdog wakes up.
> 
> Please report this to Armbian and ask them to use Mainline U-Boot, this won't happen anymore.
> 
> Neil
> 
>>
>> Thought - something about the way to trigger this reset isn't working, or a race condition is present which is being more reliably triggered? Perhaps in the dma controller or the HDMI?
>>
>> Any help to track this bug down would be very helpful, or someone else who would be interested? I can't figure out where in the stack the problem is occurring, but I guess it is the bootloader.
>>
>> Thanks,
>>
>> Matthew
>>
>>
>>
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