On Fri, Aug 30, 2013 at 1:48 PM, Tony Lindgren <tony@xxxxxxxxxxx> wrote: > * zhangfei gao <zhangfei.gao@xxxxxxxxx> [130829 04:03]: >> On Thu, Aug 29, 2013 at 4:58 PM, Linus Walleij <linus.walleij@xxxxxxxxxx> wrote: >> > On Wed, Aug 28, 2013 at 11:57 AM, Wolfram Sang <wsa@xxxxxxxxxxxxx> wrote: >> >> On Tue, Aug 20, 2013 at 04:32:28PM +0800, Zhangfei Gao wrote: >> > >> >>> Instead of use platform_driver_probe, use module_platform_driver >> >>> To support deferred probing >> >>> Also subsys_initcall may too early to auto set pinctl >> >>> >> >>> Signed-off-by: Zhangfei Gao <zhangfei.gao@xxxxxxxxxx> >> >>> Acked-by: Baruch Siach <baruch@xxxxxxxxxx> >> >> >> >> This patch is tougher than it looks. You need it, because >> >> subsys_initcall may be too early for pinctrl. >> > >> > pinctrl is initialized very early, core_initcall(). >> > >> > This is more a question of individual pin control drivers >> > and when they probe, and dependencies trying to take >> > a pinctrl handle before the pin controller is available >> > will be deferred. Even by those grabbed in the core >> > by drivers/base/pinctrl.c. >> >> Thanks Linus. >> Your explanation is really make sense. >> >> We use drivers/pinctrl/pinctrl-single.c, if subsys_initcall for >> pinctrl-single, no issue at all. > > So far we've seen that if you have issues with this, the real > problem is that some other driver is trying to initialize way > too early probably because of legacy reasons that no longer > apply. > > FYI, it's best to have all the drivers initialize with just > module_init and make them work as loadable modules because of > the following reasons: > > 1. You will get real console error messages when something > goes wrong with no need for debug_ll and earlyprintk > > 2. By creating loadable driver modules you're already getting > some protection from spaghetti code as the interfaces > are defined > > 3. It will be easier for distros to support various ARM SoCs > with loadable driver modules > > Regards, > > Tony Thanks Tony, What about concerns from Wolfram: " Other people might be depending on subsys_initcall to get I2C active before they want to activate, say, PMICs. So, I fear regressions, since deferred probing might not be available in the needed places to avoid these regressions." Is it too late using module_init for PMIC? Besides, the deferred probing still there if depend on late registered pin control driver. Thanks -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
