Hi Saravana, On Tue, 20 Feb 2024 19:28:17 -0800 Saravana Kannan <saravanak@xxxxxxxxxx> wrote: ... > > > > > > Do I understand correctly that the devlink is created between "led-5" > > > and "tca6424_dock_2" but actually should also be created between > > > "leds-dock" and "tca6424_dock_2"? > > > > > > > Yes, that's my understanding too. > > I'm replying here instead of the RESEND because here's where the > context and example are provided. > > I quickly poked into the gpio-leds driver. Please correct me if I'm > misunderstanding anything. > > It looks like led-5 will be added as a class device. But the > dev->fwnode is not set before it's added because it uses > device_create_with_groups(). So, fw_devlink doesn't create a link > between led-5 and tca6424_dock_2 unless tca6424_dock_2 is added after > led-5. Which coincidentally seems to be the case here. Might want to > explicitly create the device in gpio-leds driver. > > The issue you are trying to fix is a generic issue that I'd like to > fix in a generic fashion. It's one of my TODOs which I've mentioned > before in conferences/emails to LKML: device links framework has a > bunch of gaps when it comes to class devices. I've been thinking about > it for a while, but it needs a lot more work and testing. I'll roll in > this case when I deal with it in a generic fashion. But here's the > general idea of things that need to be addressed: > > 1. "Managed" device links allow having a class device as a supplier, > but that'll mean the consumer will never probe. > 2. What if a class device is a consumer and the supplier isn't ready. > What does it mean for the class device to be added? Is it available > for use? Probably not. Can we do something here that'll be useful for > the class implementation? > 3. What if the supplier and consumer are class devices, when does the > consumer class device become "available" (do we check the suppliers of > the supplier?)? > 4. What happens if the supplier of a class device gets removed? Do we > notify the class so it can do the right thing? Do we force unbind the > first ancestor that's on a bus? (your case). > 5. What if a supplier class device is removed, should we unbind the > consumer (if it's a bus device)? > > I'm currently working on a patch to break dependency cycles. Once > that's in, the next TODO item I work on is going to be this or clock > framework sync_state() support. > > So, I'd recommend waiting this out if it's not urgent. > > Heh, here's my commit on my local repo from a year ago when I touched > on this and realised the scope of the work. > > commit 7dcaad52e569209104408f3e472fde4ef8cd5585 (class-devlinks-v1) > Author: Saravana Kannan <saravanak@xxxxxxxxxx> > Date: Mon Feb 13 13:40:43 2023 -0800 > > add class support to device links > > > Thanks, > Saravana Did you move forward on this topic ? Best regards, Hervé
