On Thu, Apr 14, 2016 at 05:50:44PM +0200, Joerg Roedel wrote:
> Hi Bjorn,
>
> On Wed, Apr 13, 2016 at 12:56:59AM -0500, Bjorn Helgaas wrote:
> > We reverted the following changes from v4.5 to fix a regression:
> >
> > 8affb487d4a4 ("x86/PCI: Don't alloc pcibios-irq when MSI is enabled")
> > 811a4e6fce09 ("PCI: Add helpers to manage pci_dev->irq and pci_dev->irq_managed")
> > 991de2e59090 ("PCI, x86: Implement pcibios_alloc_irq() and pcibios_free_irq()")
>
> Do you have a link to the thread about these issues? I'd like to have a
> look at what has been tried to solve the regressions before the revert.
The revert was 6c777e8799a9 ("Revert "PCI, x86: Implement
pcibios_alloc_irq() and pcibios_free_irq()"").
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=111211
Email discussion: http://lkml.kernel.org/r/56A27E7E.4080609@xxxxxxxxxxxxx
> I had a look at commit 991de2e59090 and noted that the main difference
> it introduces is that the pcibios-irq is allocated earlier (probe time,
> before the commit it was pci_enable_device() time). In fact, it is now
> allocated before pci_enable_resources() has been called on the device
> (as far as I can see). I wonder if the regression can be fixed by
> also moving pci_enable_resources() to probe time.
I assume you're thinking about doing pci_enable_resources() before
the core calls the driver's probe method? One question there is how
we would deal with pci_enable_device_mem(). If the core calls
pci_enable_resources(), it has to assume the driver requires all BARs,
and there are quite a few drivers that don't need the I/O BARs.
I'd be very glad if you poked at this a little more. Jiang did a lot
of nice work on IOAPIC hotplug, and I feel bad reverting this piece of
it. It's just that nobody so far has had the time or interest to work
out a better fix.
Bjorn
--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html