Date: Wed, 27 May 2020 23:05:47 +0200 From: Hans Petter Selasky <hps@selasky.org> To: Justin Hibbits <chmeeedalf@gmail.com>, John Baldwin <jhb@FreeBSD.org> Cc: Andriy Gapon <avg@FreeBSD.org>, Konstantin Belousov <kostikbel@gmail.com>, FreeBSD Current <current@FreeBSD.org> Subject: Re: acpi timer reads all ones [Was: efirtc + atrtc at the same time] Message-ID: <41192c31-f377-0517-5fa6-ec712313d7ea@selasky.org> In-Reply-To: <20200527084107.671238bb@titan.knownspace> References: <021d8df4-a4f8-620d-73b6-b6103d0bf7f1@FreeBSD.org> <199c8845-e42c-fbee-3f13-0b3d0d7234dc@FreeBSD.org> <20200526185528.GA48478@kib.kiev.ua> <b6f5429a-fa0b-3d85-1250-a11807757ef7@FreeBSD.org> <114f788a-3947-0783-5472-173cf3a30d32@FreeBSD.org> <da33c67e-7fbd-59cc-a9b3-1b6f24fafeb2@FreeBSD.org> <618658d9-b892-9255-2747-c5efbada0210@FreeBSD.org> <20200527084107.671238bb@titan.knownspace>
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On 2020-05-27 15:41, Justin Hibbits wrote: > On Wed, 27 May 2020 06:27:16 -0700 > John Baldwin <jhb@FreeBSD.org> wrote: > >> On 5/27/20 2:39 AM, Andriy Gapon wrote: >>> On 27/05/2020 11:13, Andriy Gapon wrote: >>>> I added more diagnostics and it seems to support the idea that the >>>> problem is related to I/O cycles and bridges. >>>> >>>> ACPI timer suddenly starts returning 0xffffffff and that lasts for >>>> tens of microseconds before the timer goes back to returning >>>> normal values with an expected increase. >>>> AMD provides a proprietary way to access ACPI registers via MMIO >>>> (0xfed808xx). That mechanism is unaffected, ACPI timer register >>>> always returns good values. >>>> >>>> The problem seems to happen when restoring configuration of a >>>> particular PCI bridge. What's interesting is that the bridge >>>> decodes one memory range and one I/O range. >>>> >>>> Looking at pci_cfg_restore() I wonder if it is wise to restore >>>> PCIR_COMMAND so early. Could it be that after the resume the >>>> bridge is configured with a wrong I/O range (e.g., too wide) and >>>> by writing PCIR_COMMAND we enable that decoding. So, the bridge >>>> steals I/O cycles destined for ACPI support hardware. If there is >>>> nothing behind the bridge to handle those ports, then we get those >>>> bad readings. Once the bridge configuration is fully restored, the >>>> I/O handling goes back to normal. >>> >>> From what I see, this looks like a BIOS bug. >>> Upon resume, it swaps window configurations of pcib1 and pcib2 >>> (until FreeBSD restores them). pcib1 originally does not have an >>> I/O window. So, BIOS programs both base and limit of pcib2 I/O >>> window to zero. When FreeBSD writes its command register to >>> enable I/O decoding it starts claiming 0x0 - 0xFFF I/O port range. >>> That covers the ACPI ports at 0x8xx. >>> >>> Some printf-s. >>> From (verbose) boot time: >>> pcib1: domain 0 >>> pcib1: secondary bus 1 >>> pcib1: subordinate bus 1 >>> pcib1: memory decode 0xfea00000-0xfeafffff >>> pcib2: domain 0 >>> pcib2: secondary bus 2 >>> pcib2: subordinate bus 2 >>> pcib2: I/O decode 0xf000-0xffff >>> pcib2: memory decode 0xfe900000-0xfe9fffff >>> >>> My printf-s from resume time: >>> pcib1: old I/O base (low): 0xf1 >>> pcib1: old I/O base (high): 0x0 >>> pcib1: old I/O limit (low): 0x1 >>> pcib1: old I/O limit (high): 0x0 >>> pcib2: old I/O base (low): 0x1 >>> pcib2: old I/O base (high): 0x0 >>> pcib2: old I/O limit (low): 0x1 >>> pcib2: old I/O limit (high): 0x0 >> >> The "solution" I think is to have resume be multi-pass and to resume >> all the bridges first before trying to resume leaf devices (including >> timers), but that's a fair bit of work. It might be that we just >> need to resume timer interrupts later after the new-bus resume (I >> think we currently do it before?), though the reason for that was to >> allow resume methods in devices to sleep (I'm not sure if any do). >> > > That sounds like a good fit for https://reviews.freebsd.org/D203 . > Someone (TM) just needs to take it over the finish line... 6 years > later. Is this perhaps related to: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=237666 --HPS
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