On Fri, May 24, 2013 at 5:45 PM, Stephen Warren <swar...@wwwdotorg.org> wrote: > On 05/24/2013 02:04 AM, Linus Walleij wrote:
>> Prevention of module unloading of pin controllers has never >> been working properly, as there is no way to release the >> pinctrl handles taken by different drivers. >> >> I think that is why most pin controller drivers are bool rather >> than tristate. > > Once we get to multi-platform distro kernels, we will probably want all > the pinctrl drivers to be modules so only the correct one gets loaded > from an initrd. Hence, we'll want to move things to tristate rather than > away from it. OK ... As some kind of excuse I think the current situation is an outgrowth of the fact that all the custom set-up used to be in machines down in arch/arm/* and inevitably done at machine init. > If we know the pinctrl subsystem doesn't yet work correctly with module > unloads, should we modify pinctrl_register() to simply take a lock on > the driver module and never drop it, so that we guarantee we don't try > to unload the module later? Or, is this effectively already in place? Hm, it won't happen with anything but pinctrl-single for sure. But I know that Tony used it at one point, however I still suspect that he was only using hogs. We should maybe take the lock at the instant we instatiate a pinctrl handle from something else than a hog, so as to mark that we then have external dependencies that make unloading impossible. But it'd be even cooler to actually just iterate over the pinctrl_list och handles and orphan them, and later recouple them if a driver is loaded back in. It can surely be done, but at the cost of introducing a state lock in struct pinctrl and some pieces of hairy code in the core. Yours, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
