Date: Mon, 9 Feb 2009 12:54:06 -0500 From: John Baldwin <jhb@freebsd.org> To: Jason Harmening <jason.harmening@gmail.com> Cc: freebsd-drivers@freebsd.org Subject: Re: PCI-Express interrupt issues Message-ID: <200902091254.06917.jhb@freebsd.org> In-Reply-To: <2d1264630902090811p761b0a14w997985779aad8748@mail.gmail.com> References: <20090208113202.6d591589@CORONA> <200902090946.46917.jhb@freebsd.org> <2d1264630902090811p761b0a14w997985779aad8748@mail.gmail.com>
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On Monday 09 February 2009 11:11:20 am Jason Harmening wrote: > On Mon, Feb 9, 2009 at 8:46 AM, John Baldwin <jhb@freebsd.org> wrote: > > On Sunday 08 February 2009 12:32:02 pm Jason Harmening wrote: > >> Hi All, > >> > >> I'm the maintainer for the FreeBSD cx88 driver (multimedia/cx88). I've > >> recently encountered some issues w/ interrupt handling, specifically on > >> PCI-Express systems, and I was hoping someone would be able to help me. > >> > >> Issue #1: > >> > >> The cx88 driver has split interrupt handling between filters and > >> ithreads since filters became available w/ 7.0. For the past year, the > >> filters have been set up to return FILTER_SCHEDULE_THREAD if the status > >> register indicates an interrupt, FILTER_STRAY otherwise. Everything > >> has worked fine. > >> > >> However, I recently stumbled across some documentation indicating that > >> FILTER_SCHEDULE_THREAD shouldn't be returned alone--instead, the filter > >> should return FILTER_HANDLED | FILTER_SCHEDULE_THREAD. So I modified > >> the cx88 driver to do that instead, and that's where things turned > >> strange: > >> > >> On machine #1, which uses a VIA K8T800 chipset, everything still worked > >> fine. > >> > >> On machine #2, which uses a VIA K8T890 chipset, the threaded interrupt > >> handlers were no longer invoked. It's as though the bus driver saw > >> FILTER_HANDLED in the bitmask and assumed the interrupt was already > >> processed without checking to see if an ithread should be scheduled. > >> What's interesting is that the only significant difference between the > >> K8T800 in machine #1 and the K8T890 in machine #2 is that the K8T890 > >> supports PCI-Express, while the K8T800 is PCI-only. > > > > Are you seeing this only on 7.0? Also, do you have 'INTR_FILTER' enabled in > > the kernel? If you don't, then your ithread will never be called if you have > > a filter (actually, the bus_setup_intr() should fail in that case if you > > specify both). > > All machines are running 7.1-STABLE. Filters are enabled across the > board, and reverting to just returning FILTER_SCHEDULE_THREAD fixes > the issue. Do you see a dedicated interrupt thread for your device in top/ps? It should be 'intr: pcm0' (or whatever the device name is). -- John Baldwin
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