Hi, Thanks for your answer On Tue, Nov 07, 2023 at 04:26:34PM +0100, Greg Kroah-Hartman wrote: > On Tue, Nov 07, 2023 at 01:18:14PM +0100, Maxime Ripard wrote: > > On Tue, Nov 07, 2023 at 12:22:21PM +0100, Greg Kroah-Hartman wrote: > > > On Tue, Nov 07, 2023 at 11:57:49AM +0100, Maxime Ripard wrote: > > > > +GKH > > > > > > Why? I don't see a question for me here, sorry. > > > > I guess the question is: we have a bus with various power states > > (powered off, low power, high speed) > > Great, have fun! And is this per-device or per-bus-instance? Per bus instance > > low power is typically used to send commands to a device, high speed to > > transmit pixels, but still allows to send commands. > > > > Depending on the devices, there's different requirements about the state > > devices expect the bus to be in to send commands. Some will need to send > > all the commands in the low power state, some don't care, etc. See > > the mail I was replying too for more details. > > > > We've tried so far to model that in KMS itself, so the framework the > > drivers would register too, but we're kind of reaching the limits of > > what we can do there. It also feels to me that "the driver can't access > > its device" is more of a problem for the bus to solve rather than the > > framework. > > This is up to the specific bus to resolve, there's nothing special > needed in the driver core for it, right? Yeah, we weren't really looking to handle this into the driver core, but rather if there was a set of guidelines or feedback on implementing those kind of features for a bus. > > Do you agree? Are you aware of any other bus in Linux with similar > > requirements we could look at? Or any suggestion on how to solve it? > > There might be others, yes, look at how the dynamic power management > works for different devices on most busses, that might help you out > here. Thanks for the pointers, we'll have a look Maxime
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