Daniel Barkalow wrote:
On Fri, 19 Oct 2007, Jeff Garzik wrote:
Linas Vepstas wrote:
On Fri, Oct 19, 2007 at 09:17:23PM +0800, Shane Huang wrote:
Since we have little experience on PCI and MSI here, we had to try to
As someone else pointed out, AMD should have *lots* of people with
pci and msi experience on the payroll. (Folks here buy AMD-designed pci
chips ...)
ONLY
comment out the pci_intx() call in drivers/ata/ahci.c
My system can boot up too with MSI enabled!
So does it mean that the root cause is our SB700 SATA controller
has a hardware bug where setting INTX_DISABLE in the PCI COMMAND
register masks MSI interrupts too?
That's what it sounds like, to me.
And what is the software solution or workaround?
Not sure. Sounds like the device driver needs a quirk for this part.
Take a look at tg3.c net driver change
2fbe43f6f631dd7ce19fb1499d6164a5bdb34568 which is a similar situation.
However, it may turn out that removing the pci_intx() stuff as a general rule
is easier than quirking these devices, if enough of them turn out to have this
hardware bug.
At a first approximation, ATI/AMD devices don't send any interrupts if
intx is disabled, nVidia devices send legacy interrupts in addition to MSI
ones if intx isn't disabled, and Intel devices actually work correctly. So
we need at least one kind of device quirk for intx and msi. (And doing it
in the drivers doesn't work, since everybody is making things driven by
snd_hda_intel and would like msi, afaict)
Note that INTX_DISABLE is a recent addition to PCI. Older PCI devices
support neither MSI nor INTX-disable, so make sure such devices don't
creep into your sample.
In general it is documented that INTX_DISABLE should apply only to INTx#
so devices that disable MSI based on that bit are out of spec. But
unfortunately that is rather irrelevant, since we see these out-of-spec
devices in the field today.
Jeff
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