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

Marek Szyprowski m.szyprowski at samsung.com
Thu Jun 16 23:24:23 PDT 2016

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 at samsung.com>  wrote:
>> From: Krzysztof Kozlowski<k.kozlowski at samsung.com>
>> 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 at samsung.com>.
>> Signed-off-by: Krzysztof Kozlowski<k.kozlowski at samsung.com>
>> Signed-off-by: Marek Szyprowski<m.szyprowski at samsung.com>
> 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

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