Messages in this thread | | | Subject | Re: Kernel Options: To use MSI-X or not? | From | Valdis.Kletnieks@vt ... | Date | Wed, 04 Nov 2009 12:36:51 -0500 |
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On Wed, 04 Nov 2009 11:53:18 EST, Justin Piszcz said:
> Example, 3ware cards/Intel Audio Drivers you can use MSI-X instead of > having several devices use/share an interrupt. > > What are the pros/cons to using MSI-X vs. having devices share an IRQ?
Cons: Sometimes, you'll find a device that claims to support MSI but in fact is to some extent borked...
I'm the proud owner of a Dell Latitude D820, which includes this PCI:
00:1b.0 Audio device: Intel Corporation 82801G (ICH7 Family) High Definition Audio Controller (rev 01) Subsystem: Dell Device 01cc Flags: bus master, fast devsel, latency 0, IRQ 30 Memory at efffc000 (64-bit, non-prefetchable) [size=16K] Capabilities: [50] Power Management version 2 Capabilities: [60] MSI: Enable+ Count=1/1 Maskable- 64bit+ Capabilities: [70] Express Root Complex Integrated Endpoint, MSI 00 Capabilities: [100] Virtual Channel <?> Capabilities: [130] Root Complex Link <?> Kernel driver in use: HDA Intel
However, actually trying to enable MSI gets me this at some pseudo-random time after booting (one for each of 7 boots):
[ 4.519264] ALSA sound/pci/hda/hda_intel.c:683: No response from codec, disabling MSI: last cmd=0x00df0900 [ 22.788015] ALSA sound/pci/hda/hda_intel.c:683: No response from codec, disabling MSI: last cmd=0x008f0c00 [ 4.719263] ALSA sound/pci/hda/hda_intel.c:683: No response from codec, disabling MSI: last cmd=0x00df0900 [ 12.497263] ALSA sound/pci/hda/hda_intel.c:683: No response from codec, disabling MSI: last cmd=0x00df0900 [ 815.350265] ALSA sound/pci/hda/hda_intel.c:683: No response from codec, disabling MSI: last cmd=0x00df0900 [ 595.171267] ALSA sound/pci/hda/hda_intel.c:683: No response from codec, disabling MSI: last cmd=0x00171700 [ 4.968263] ALSA sound/pci/hda/hda_intel.c:683: No response from codec, disabling MSI: last cmd=0x00df0900
(Am slightly mystified about the resets at 4 and 12 seconds - at that point, we're not up far enough to actually try to use the audio. I suspect udev trying to initialize the card - except sometimes it works and runs just fine with MSI for quite some time:
[14267.701267] ALSA sound/pci/hda/hda_intel.c:683: No response from codec, disabling MSI: last cmd=0x00df0900 [12841.892050] ALSA sound/pci/hda/hda_intel.c:683: No response from codec, disabling MSI: last cmd=0x00df0900 [10647.783274] ALSA sound/pci/hda/hda_intel.c:683: No response from codec, disabling MSI: last cmd=0x001f1500 [15091.102034] ALSA sound/pci/hda/hda_intel.c:683: No response from codec, disabling MSI: last cmd=0x00171700 [20085.955293] ALSA sound/pci/hda/hda_intel.c:683: No response from codec, disabling MSI: last cmd=0x00df0700
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