Den 17.10.2015 20:45, skrev Rob Clark: > On Sat, Oct 17, 2015 at 2:27 PM, Greg Kroah-Hartman > <gregkh at linuxfoundation.org> wrote: >> On Sat, Oct 17, 2015 at 01:54:43PM -0400, Rob Clark wrote: >>> On Sat, Oct 17, 2015 at 12:56 PM, Greg Kroah-Hartman >>> <gregkh at linuxfoundation.org> wrote: >>>>> I'm guessing the time is a matter of probing and undoing the probes >>>>> rather than slow h/w. We could maybe improve things by making sure >>>>> drivers move what they defer on to the beginning of probe, but that >>>>> seems like a horrible, fragile hack. >>>> How can calling probe and failing cause 2 seconds? How many different >>>> probe calls are failing here? Again, a boot log graph would be great to >>>> see as it will show the root cause, not just guessing at this. >>> >>> just fwiw, but when you have a driver that depends on several other >>> drivers (which in turn depend on other drivers and so on), the amount >>> of probe-defer we end up seeing is pretty comical. Yeah, there >>> probably is some room to optimize by juggling around order drivers do >>> things in probe. But that doesn't solve the fundamental problem with >>> the current state, about probe order having no clue about >>> dependencies.. >> I can imagine it is a lot of iterations, but how long does it really >> take? How many different devices are involved that it takes multiple >> loops in order to finally work out the correct order? Where is the time >> delays here, just calling probe() and having it instantly return >> shouldn't take all that long. > offhand, I think the dependencies go at *least* three levels deep.. > I'd say, from memory, I see drm/msm taking at least 5 or 6 tries to > get all the way through requesting it's various different > regulators/clks/gpios. I hadn't really paid attention to how many > tries the drivers I depend on go through. (Of those, I take clks from > two different clk drivers (which have dependency on a 3rd clk driver), > and regulators and gpio's come from at least two places, which in turn > have dependencies on clks, etc.) I don't have really good hard > numbers handy (since my observations of this are w/ console over uart > which effects timings, and so I see it taking much longer than 2sec).. > but the 2sec figure that Tomeu mentioned seemed pretty plausible to > me. > > I can try to get better #'s... I should have my kernel hat on at least > some of the time next week.. but the 2sec figure didn't seem > unrealistic to me.
Are you saying that the total boot time is increased by 2 sec due to deferred probing, or that display initialization is happening 2 sec after it's first try?