On Thu, Oct 07, 2021 at 04:46:22PM -0400, Stephen Boyd wrote: > Quoting Andrzej Hajda (2021-10-07 03:16:27) > > Hi Stephen, > > > > On 06.10.2021 21:37, Stephen Boyd 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 aggregate 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. I no longer get a warning from i2c > > > at shutdown that we're trying to make an i2c transaction after the i2c > > > bus has been shutdown. There's more work to do on the msm drm driver to > > > extract component device resources like clks, regulators, etc. out of > > > the component bind function into the driver probe but I wanted to move > > > everything over now in other component drivers before tackling that > > > problem. > > > > > > As I understand you have DSI host with i2c-controlled DSI bridge. And > > there is an issue that bridge is shutdown before msmdrm. Your solution > > is to 'adjust' device order on pm list. > > I had similar issue and solved it locally by adding notification from > > DSI bridge to DSI host that is has to be removed: mipi_dsi_detach, this > > notification escalates in DSI host to component_del and this allow to > > react properly. > > > > Advantages: > > - it is local (only involves DSI host and DSI device), > > - it does not depend on PM internals, > > - it can be used in other scenarios as well - unbinding DSI device driver > > > > Disadvantage: > > - It is DSI specific (but this is your case), I have advertised some > > time ago more general approach [1][2]. > > > > [1]: https://static.sched.com/hosted_files/osseu18/0f/deferred_problem.pdf > > [2]: https://lwn.net/Articles/625454/ > > > > I think these are all points for or against using the component code in > general? Maybe you can send patches that you think can solve the problem > I'm experiencing and we can review them on the list. Yeah I think this is entirely orthogonal. If you use component, then component should provide a way to handle this. If you use something else, like drm_bridge or dsi or whatever, then that part should provide a solution to stage stuff correctly and handle all the ordering. Now there's a bunch of drivers which mix up component with bridge use and hilarity ensues, but since there's no real effort to fix that I think it's toally fine to just improve component.c meanwhile. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch
