On Wed, May 19, 2021 at 09:41:27PM -0400, Stephen Boyd wrote: > Quoting Saravana Kannan (2021-05-19 18:27:50) > > On Wed, May 19, 2021 at 5:25 PM Stephen Boyd <swboyd@xxxxxxxxxxxx> wrote: > > > > > > This series is from discussion we had on reordering the device lists for > > > drm shutdown paths[1]. I've introduced an 'aggregate' bus that we put > > > the aggregate device onto and then we probe the device once all the > > > components are probed and call component_add(). The probe/remove hooks > > > are where the bind/unbind calls go, and then a shutdown hook is added > > > that can be used to shutdown the drm display pipeline at the right time. > > > > > > This works for me on my sc7180 board, but I'm currently struggling with > > > the last patch where we migrate the msm driver. It runs into a runtime > > > PM problem where the parent device isn't runtime PM enabled yet. I'm > > > still trying to figure out a clean solution there. Moving runtime PM > > > around breaks boot and I think that's because the power domain is off. > > > > > > Cc: Daniel Vetter <daniel.vetter@xxxxxxxx> > > > Cc: "Rafael J. Wysocki" <rafael@xxxxxxxxxx> > > > Cc: Rob Clark <robdclark@xxxxxxxxx> > > > Cc: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx> > > > Cc: Saravana Kannan <saravanak@xxxxxxxxxx> > > > > > > [1] https://lore.kernel.org/r/20210508074118.1621729-1-swboyd@xxxxxxxxxxxx > > > > > > > I skimmed through the series and in general the idea is good, but I'm > > not sure why each component user needs to be converted/"modern" before > > it can make use of the benefits of this series. Why not just have > > wrapper functions around the component ops that the new aggregate bus > > driver can just call? That'll give all the existing component users > > the new ability to use the new ops without having to have two > > versions. > > The existing users can only have one or the other. Either use the ops > structure or use the struct aggregate_driver. What benefits of this > series are they not gaining? > > > That'll also allow us to do other improvements (I have some > > in mind) that'll apply to all the component users instead of only the > > converted ones. > > What do you have in mind? I didn't want to convert drivers over to the > new way of doing things without making them consciously change their > code. Otherwise I worry it will break things in random, subtle ways. The > last patch, as I mentioned above in the cover, causes warnings because > the display driver is enabling runtime PM in an odd spot as part of the > bind callback of the aggregate/master. That should move out of there and > into the msm_pdev driver that registers the aggregate from what I can > tell. Hm yeah that's annoying. Another thing to check is that there's no locking issues with lockdep enabled. But there's plenty of other places that register/bind drivers within other drivers, so it should all work. I think this is a good reason why more drivers should be converted (in separate patches) so that we get a lot more testing and can find bugs in the design. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch
