Len Ovens wrote: > On Wed, 30 Apr 2014, Clemens Ladisch wrote: >> Len Ovens wrote: >>> PCI bridge: Intel Corporation 8 Series/C220 Series Chipset Family PCI Express Root Port #3 (rev d5) >>> 00:1c.3 PCI bridge: Intel Corporation 82801 PCI Bridge (rev d5) >>> >>> I am not sure which is which. The first may be the express port. >> >> The ASM1083 (which the manual says you have) should be listed as "ASM1083". >> What is the output of "lspci -t"? > > len@music:~$ lspci -t > -[0000:00]-+-00.0 > +-01.0-[01]-- > +-02.0 > +-14.0 > +-16.0 > +-1a.0 > +-1c.0-[02]-- > +-1c.2-[03]----00.0 > +-1c.3-[04-05]----00.0-[05]--+-00.0 > | \-02.0 > +-1d.0 > +-1f.0 > +-1f.2 > \-1f.3 > > 00:1c.3 would be the PCI bridge then as my two audio cards are listed > as 05:00.0 and 05:02.0. I would guess that the third PCI slot would be > 01. I see that the bridge is listed as [04-05] I am guessing that > means 04 is the PCIe side and 05 is the PCI side? Device 00:1c.3 is one of the PCIe ports of the southbridge. Device 04:00 is the ASM1083 PCIe/PCI bridge. Devices 05:xx are the chips on the PCI cards. Bus 00: is the "root complex", i.e., CPU/northbridge/southbridge. Bus 04: is the PCIe connection between the southbridge and the ASM1083. Bus 05: is the PCI bus. "[04-05]" means that both buses are reachable through this bridge. > So it sounds like you are saying that the PCIe devices are assigned > an irq to be compatible with the PCI standard, but most PCIe devices > don't use the irq having another way to get the OS attention. There are different kinds of interrupts. 0-15 are ISA-compatible interrupts; the next four or eight can be used for PCI interrupts. (The interrupt controller (IOAPIC) has only a limited number of interrupt lines.) Message-signaled interrupts (MSIs) are implemented with a different mechanism and do not need to go through the IOAPIC; you can have any number of them, and they are never shared between devices. > Looking at /proc/interrupts, I see that ahci (which from lspci seems > to be the SATA controller) shows irq 42 even though the book says it > is sharing an irq with PCI slot 1 which has an ens1370 at irq 19. So > I would guess that this irq 42 is a "soft" irq? Yes, it's an MSI. > (and why do I have an ISA bridge?) Because you have ISA devices. (Intel likes to call them "legacy", but they are still there.) > I would guess that if I installed a PCIe card that was PCI HW with > a PCIe->PCI bridge on the card to update it, that it would still use > the old irq and could clash with one of my other PCI audio cards. Yes. Regards, Clemens _______________________________________________ Linux-audio-user mailing list Linux-audio-user@xxxxxxxxxxxxxxxxxxxx http://lists.linuxaudio.org/listinfo/linux-audio-user
