Re: [PATCH 1/3] PM / Runtime: Add notifiers for device runtime PM events

[Marek Szyprowski]

Hi Rafael,


On 2016-06-08 19:18, Rafael J. Wysocki wrote:
> On Wed, Jun 8, 2016 at 12:25 PM, Marek Szyprowski
> <m.szyprowski@xxxxxxxxxxx>  wrote:
> > From: Krzysztof Kozlowski<k.kozlowski@xxxxxxxxxxx>
> >
> > Allow drivers registering for certain runtime PM events of other
> > devices. Some drivers in power domain are more or less coupled. When one
> > driver is suspending (thus leading to power domain being also turned
> > off) the other might have to perform some necessary steps. For example
> > Exynos IOMMU has to save its context.
> >
> > Based on previous work of Sylwester Nawrocki<s.nawrocki@xxxxxxxxxxx>.
> >
> > Signed-off-by: Krzysztof Kozlowski<k.kozlowski@xxxxxxxxxxx>
> > Signed-off-by: Marek Szyprowski<m.szyprowski@xxxxxxxxxxx>
> No, this is not the right way to address this and using notifiers for
> that is just wrong (because of the potential ordering issues).
>
> Also, the problem is not limited to runtime PM, but also to system
> suspend/resume and initialization/shutdown.
>
> I posted a series of device dependencies patches a few months ago that
> might help to address this problem, but there was almost no interest
> in it at that time.

I spent some time digging for your patches. Sadly no list archives had
them all and I finally found them only in the linux-pm patchwork. This
may explain why there was almost no interest in them.

After some debugging I've managed to get it working for my case. I will
include your patches in my v2 patchset together with the fixes needed to
get it working.

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