[PATCH v2 0/6] Switch to generic syscon regmap based drivers

Alim Akhtar alim.akhtar at samsung.com
Wed Oct 21 03:44:23 PDT 2015

Hi Javier,

On 10/21/2015 03:46 PM, Javier Martinez Canillas wrote:
> Hello Alim,
> On 10/21/2015 08:09 AM, Alim Akhtar wrote:
> [snip]
>>>>>> Hi Alim,
>>>>>> I have installed your patch set above with git am on top of
>>>>>> 4.3.0-rc6-00108-gce1fad2 torvalds/linux of today
>>>>>> with make exynos_defconfig on Odroid U3.
>>>>> which exynos soc Odroid U3 uses?
>>>> OK, I can see its uses exynos4412 and exynos4412-odroidu3.dts does
>>>> include exynos4.dtsi,
>>>> so these should have worked.
>>>>>> "halt -p" worked (power 0.0W).
>>>>>> "reboot" got stuck at 0.5W.
>>>>> reboot stuck mean system does not reboot any more?
>>> It freezes when going for reboot.
>>> Have to power off/on to boot again.
>>> Btw I use an mmc, not an sd-card.
>>> No other HW connected, just LAN-cable.
>>> Bootloader is u-boot v2015.10.
>>> o
>> Have checked on 4.3.0-rc6-00006-gd03c139e7e77, still works on peach boards.
>> Sorry I don't have Odroid U3 with me, may be Javier or Krzysztof might help here to check whats wrong. To me its looks more of a board specific issue for now.
> Krzysztof has an Odroid XU3 lite and I have an Odroid XU4, both uses an
> Exynos5422 so we can't check what's wrong with Odroid U3 (Exynos4412).
> Having said that I think I know what is the issue here. Markus said that
> he is using an eMMC instead of an uSD (which is what I used and my guess
> is that Krzysztof did too).
> Now, there is a subtle difference between the old PMU restart handler
> and the syscon-reboot one, and that is the restart handler priorities:
> notifier                    priority
> ------------------------------------
> pmu_restart_notify          128
> mmc_pwrseq_emmc_reset_nb    129
> syscon_restart_handle       192
> So, without Alim's patches, first the eMMC reset handler will be called
> and then the PMU restart handler but after his series, the syscon reset
> handler has a higher priority so the eMMC reset will never be called.
> But the problem is that the eMMC card has to be properly reset on system
> restart to allow the SoC iROM to be able to read the bootloader from the
> eMMC since the iROM doesn't have restart logic and the card shouldn't be
> left in an unknown state.
> So the problem here is not that the system is not being reset (that I
> think that works) but that on reboot, the system is not able to boot
> again since the ROM is not able to read the second stage bootloader.
Thanks for nailing it down, this make lots of sense and probably the 
main cause of Odroid U3 reboot failure.
I was going to suggest Markus to try a uSD boot. But looks like your 
suggested patch will do the trick for him.

> Markus,
> Can you please test following patch [0] on top of Alim's series? If that
> works then it should either be part of Alim's series or the patches will
> have to wait until that patch lands into mainline. I don't have an eMMC
> to test it in XU4 but I'm pretty confident that it will solve the issue.
I am fine with including this with my series or lowering 
syscon_restart_handler priority to 128.
It also make sense to increase eMMC priority as you suggested as before 
system reboot, devices should have reseted itself.

> Best regards,

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