Re: [PATCH v2 00/10] Exynos IOMMU: proper runtime PM support (use device dependencies)

From: Marek Szyprowski
Date: Tue Jul 19 2016 - 02:26:30 EST

Hi Tobias

On 2016-07-18 18:43, Tobias Jakobi wrote:
Marek Szyprowski wrote:
On 2016-07-18 13:00, Tobias Jakobi wrote:
Marek Szyprowski wrote:
On 2016-07-15 15:21, Tobias Jakobi wrote:
Tobias Jakobi wrote:
Hello Marek,

I've tested the patchset on 4.7-rc7 and noticed that it breaks
reboot on

Going to check where exactly things break.
Sadly it's the last patch where everything comes together:
"iommu/exynos: Add proper runtime pm support"

I still have to check if forcing runpm status to 'on' makes a
difference. I suspect that the aggressive clock gating might be the
Thanks for testing. I will check this issue. Could you send me your
This is the config I'm currently using:

Do you think checking this with no_console_suspend makes sense?
no_console_suspend switch won't provide more information, but I managed
to reproduce your issue. I'm really confused how enabling runtime pm can
cause problems with usb/smsc95xx ethernet driver (that is the reason for
failed reboot). Maybe it is somehow related to the global relations
between devices and drivers and the fact that creating the runtime pm
links change the order of operations. I will check this again when
Rafael send updated patches. Here is the log I got (after waiting some
thanks for looking into this! I'll try to reproduce this on my board. I
have to admit that I didn't wait too long for the hung task message to

I wonder if this has something to do with regulator code cutting some
supplies too early. Is this on a X2 or a U2/U3?

I've reproduced it on U3.

I'm not sure if we
currently model the regulator setup correctly here (IIRC then buck8 is
supplying the LAN/USB block on U2/U3).

IMHO it is not really related to regulator operations, but the sequence
of shutting down logical devices in the system. For some reasons when pm links
are used, something changes the order of operations in system shutdown
procedure, what causes smsc95xx to hang. I have no idea why, but I don't have
time to investigate it further. I will wait for the next release of Rafael's
pm links patches and then check everything again.

Best regards
Marek Szyprowski, PhD
Samsung R&D Institute Poland