Re: [PATCH v4 0/5] Functional dependencies between devices

[Marek Szyprowski]

Hi Rafael,

On 2016-09-29 02:24, Rafael J. Wysocki wrote:
> Hi Everyone,
>
> On Thursday, September 08, 2016 11:25:44 PM Rafael J. Wysocki wrote:
> > > Hi Everyone,
> > >
> > > This is a refresh of the functional dependencies series that I posted last
> > > year and which has picked up by Marek quite recently.  For reference,
> > > appended is my introductory message sent previously (which may be
> > > slightly outdated now).
> > >
> > > As last time, the first patch rearranges the code around
> > > __device_release_driver() a bit to prepare it for the next one (it
> > > actually hasn't changed AFAICS).
> > >
> > > The second patch introduces the actual device links mechanics, but without
> > > system suspend/resume and runtime PM support which are added by the
> > > subsequent patches.
> > >
> > > Some bugs found by Marek during his work on these patches should be fixed
> > > here.  In particular, the endless recursion in device_reorder_to_tail()
> > > which simply was broken before.
> > >
> > > There are two additional patches to address the issue with runtime PM
> > > support
> > > that occured when runtime PM was disabled for some suppliers due to a PM
> > > sleep transition in progress.  Those patches simply make runtime PM
> > > helpers
> > > return 0 in that case which may be controversial, so please let me know if
> > > there are concerns about those.
> > >
> > > The way device_link_add() works is a bit different, as it takes an
> > > additional
> > > status argument now.  That makes it possible to create a link in any
> > > state,
> > > with extra care of course, and should address the problem pointed to by
> > > Lukas
> > > during the previous discussion.
> > >
> > > Also some comments from Tomeu have been addressed.
> > An update here.
> >
> > The first patch hasn't changed, so I'm resending it.
> >
> > The majority of changes in the other patches are in order to address Lukas'
> > comments.
> >
> > First off, I added a DEVICE_LINK_STATELESS flag that will prevent the driver
> > core from trying to maintain device links having it set.
> >
> > Also, the DEVICE_LINK_PERSISTENT flag was dropped (as link "persistence" is
> > the default behavior now) and there's a new one, DEVICE_LINK_AUTOREMOVE,
> > that will cause the driver core to remove the link on the consumer driver
> > unbind.
> >
> > Moreover, the code checks attempts to create a link between a parent and a
> > child device now and actively prevents that from happening.
> >
> > The changelog of the second patch has been updated as requested by Ulf.
> >
> > The third patch was updated to fix a bug related to the (previously missing)
> > clearing of power.direct_complete for supplier devices having consumers that
> > don't use direct_complete.
> >
> > The next two (runtime PM) patches turned out to be unnecessary, so I've
> > dropped them.
> >
> > The runtime PM patch [4/5] was reorganized somewhat to reduce the
> > indentation
> > level in there, but the code flow introduced by it is essentially the same
> > and the last patch was simply rebased on top of the new series.
> Time for another update. :-)
>
> Fewer changes this time, mostly to address issues found by Lukas and Marek.
>
> The most significant one is to make device_link_add() cope with the case when
> the consumer device has not been registered yet when it is called.  The
> supplier device still is required to be registered and the function will return
> NULL if that is not the case.
>
> Another significant change is in patch [4/5] that now makes the core apply
> pm_runtime_get_sync()/pm_runtime_put() to supplier devices around the probing
> of a consumer one (in analogy with the parent).

Thanks for the update! Updated version fixes all the remaining issues.

Tested-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>

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