On Wed, May 14, 2014 at 3:58 PM, Alexander Holler <holler@xxxxxxxxxxxxx> wrote: > Am 14.05.2014 16:13, schrieb Grant Likely: > >> On Mon, 12 May 2014 18:47:56 +0200, Alexander Holler >> <holler@xxxxxxxxxxxxx> wrote: >>> >>> The init system currently calls unknown functions with almost unknown >>> functionality in an almost random order. >> >> >> Correct, we've got a module system. Some would say that is a strength! >> :-) That said, I don't object to optimizing to the optimal order when >> possible. > > > Modules do work after init happened, that isn't what this feature is about. Oops, I meant modular. I wasn't talking about modules either. The driver model is designed to match devices with drivers regardless of the order that either of them get registered to the system. I think that is a strong aspect of the drivercore. What it doesn't have is any way of optimizing the probe order, which is at the heart of your proposal. > > >> >>> Fixing this is on a short-term basis is a bit tricky. >>> >>> In order to register drivers with a deterministic order, a list of all >>> available in-kernel drivers is needed. Unfortunately such a list doesn't >>> exist, just a list of initcalls does exist. >>> >>> The trick now is to first call special annotated initcalls (I call those >>> "well done") for platform drivers, but not actualy starting those drivers >>> by calling their probe function, but just collectiong their meta datas >>> (struct platform_driver). After all those informations were collected, >>> available the drivers will be started according to the previously >>> determined order. >> >> >> Why does the initcall level matter? Why not just let the initcalls >> happen, capture the calls that register a driver, and then use that list >> later? > > > Some initcalls assume that stuff is present when they called probe or > register and do further action based on the rc code. What I mean is that manipulating the initcall level isn't the best way to handle it. We've got enough initcalls and there isn't a need to add more. Other ways to handle the problem would be to either have a variant of the platform_driver_register() that triggers your desired behavour, or add a flag to the struct device_driver that tells the driver core that it should try to resolve ordering. In both cases the module_platform_driver() macro can do the magic bit. Other drivers will have to do it manually. g. -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
