Date: Fri, 24 May 2013 08:08:21 -0700 From: Justin Hibbits <jrh29@alumni.cwru.edu> To: Warner Losh <imp@bsdimp.com> Cc: freebsd-arch@freebsd.org Subject: Re: late suspend/early resume Message-ID: <CAHSQbTBBQnvtqXiXq_vOK=%2Bvt78P2LBGQTi7i-EnOV77w7UDng@mail.gmail.com> In-Reply-To: <780B27A1-AA4F-4382-BE33-7587BD9EB615@bsdimp.com> References: <CAHSQbTBNjrx=9DT7vk29D=Y%2BOK0qV=Ld4qN-sxy%2B8_OONazKAA@mail.gmail.com> <AE98E779-E22B-434D-9BEE-BF66241BB2E6@bsdimp.com> <51913B7D.1040801@freebsd.org> <288C9B9E-E943-4C5B-BCFB-15B721CBE94C@bsdimp.com> <CAHSQbTCEOfCH5tLeWgP4gPVbsBwDKLKBboQ2d74npkQomoJJJQ@mail.gmail.com> <519369C4.6060402@FreeBSD.org> <CAHSQbTDQQz1r%2BpsH3-Z6DESLoenXcjnefsNxZO7NtbboMtJ0rw@mail.gmail.com> <780B27A1-AA4F-4382-BE33-7587BD9EB615@bsdimp.com>
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On Thu, May 23, 2013 at 10:11 PM, Warner Losh <imp@bsdimp.com> wrote: > > On May 23, 2013, at 11:08 PM, Justin Hibbits wrote: > > > John, > > > > > > On Wed, May 15, 2013 at 3:56 AM, John Baldwin <jhb@freebsd.org> wrote: > > > >> On 5/14/13 1:14 PM, Justin Hibbits wrote: > >>> You are right that the late suspend could lead to silly proliferation, > >> and > >>> an ordered list is much better, but another API would need to be added > to > >>> do that as well. > >>> > >>> My north bridge is first in the top list of the tree, right under the > >>> nexus, so to suspend it last I wrote the nexus suspend to traverse its > >>> children in reverse. The problem comes that the clock controller is > >> under a > >>> later PCI bus, not even the immediate following one, and the north > bridge > >>> children are i2c devices, so suspending them after their clock head > away > >> is > >>> problematic. We can discuss this more at bsdcan, where it may be > easier > >> to > >>> describe. But essentially I need the north bridge and that pesky clock > >>> controller to be the last to suspend and the first to resume. I guess > we > >>> can take this as the starting discussion for modeling this relationship > >> on > >>> all platforms, since you mention it is common in embedded platforms. > >> > >> I think you can do this by having a notion of passes with drivers having > >> a suspend pass level and doing passes over the tree suspending devices > >> at each pass level and then walking the passes back up in reverse during > >> resume. You could borrow from the multipass stuff used on probe/attach > >> for this. > >> > >> -- > >> John Baldwin > >> > > > > I have an update in the projects/pmac_pmu branch. It works for my > > PowerBook, but I'm not certain how well it will fare in the end, because > of > > the way the PCI driver resumes its children. It doesn't call > > bus_generic_resume(), and instead suspends each child individually, which > > can lead to devices being resumed multiple times, but I'm uncertain how > to > > fix that. Any ideas? One I had was to have some kind of > > 'bus_generic_resume_filtered' or similar, that lets bus_generic_resume > run > > its logic, but filter through a function to determine if the child is > > resumable. But that doesn't quite feel right to me. > > How does it lead there? Did you change the suspend/resume function > signatures? Or did you create new ones like I suggested that had a default > method that called the old suspend/resume function iff pass was the last > one.... > > > Warner > > I must've misunderstood you during our discussion. I simply reused the existing bus_generic_suspend/resume, and used EAGAIN to pass a token of 'rescan this again'. - Justin
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