Re: libata, devm_*, and MSI ?

From: Michael Ellerman
Date: Tue Jan 20 2009 - 23:16:34 EST

On Tue, 2009-01-20 at 20:02 -0800, Grant Grundler wrote:
> On Tue, Jan 20, 2009 at 7:39 PM, Mark Lord <liml@xxxxxx> wrote:
> ...
> > Next.. who knows something about debugging MSI across PCI bridges ?
> > I've got a 64-bit box here, PCIe near the core, but with full PCI-X
> > slots on the far side of two bridges.
> >
> > The kernel happily allows my driver to setup MSI, but the interrupts
> > never arrive. So something somewhere in between is either
> >
> > (1) not set up or quirked quite right, or
> > (2) one of the bridges won't pass MSI and we don't detect that.
> >
> > I'll poke more at it later and post some info, if somebody out there
> > knows enough about this kind of thing to provide some basic hints.
> Basic Hints:
> 1) post lspci -v output to verify device (and bridges) is programmed correctly.
> 2) look for chipset quirks that disable global msi

The kernel shouldn't let you enable MSI if that's the case, ie.
pci_enable_msi() should fail.

It might still be worth looking at the quirks though, in case there's
one for a previous revision of your bridge or something.

> 3) Make sure MMIO ranges for 0xfee00000 are routed to local APIC
> ie each bridge needs to route that address somehow (negative decode
> is common for upstream).
> 4) manually trigger the MSI by doing a MMIO write to the correct
> 0xfee00000 address with the assigned vector in order to see if your
> interrupt handler gets called.

And can you plug something directly into the PCIe bus? If so does MSI
work on that?


Michael Ellerman
OzLabs, IBM Australia Development Lab

phone: +61 2 6212 1183 (tie line 70 21183)

We do not inherit the earth from our ancestors,
we borrow it from our children. - S.M.A.R.T Person

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