Re: Aw: Re: [PATCH] pci: mediatek: fix warning in msi.h

[Marc Zyngier]

On 2020-11-03 10:16, Thomas Gleixner wrote:
> On Tue, Nov 03 2020 at 09:54, Marc Zyngier wrote:
> > On 2020-11-02 22:18, Thomas Gleixner wrote:
> > > On Mon, Nov 02 2020 at 17:16, Thomas Gleixner wrote:
> > > > On Mon, Nov 02 2020 at 11:30, Marc Zyngier wrote:
> > > > > --- a/drivers/pci/probe.c
> > > > > +++ b/drivers/pci/probe.c
> > > > > @@ -871,6 +871,8 @@ static void pci_set_bus_msi_domain(struct 
> > > > > pci_bus
> > > > > *bus)
> > > > >   		d = pci_host_bridge_msi_domain(b);
> > > > >
> > > > >   	dev_set_msi_domain(&bus->dev, d);
> > > > > +	if (!d)
> > > > > +		bus->bus_flags |= PCI_BUS_FLAGS_NO_MSI;
> > > >
> > > > Hrm, that might break legacy setups (no irqdomain support). I'd 
> > > > rather
> > > > prefer to explicitly tell the pci core at host registration time.
> > >
> > > s/might break/ breaks /     Just validated :)
> >
> > For my own edification, can you point me to the failing case?
>
> Any architecture which selects PCI_MSI_ARCH_FALLBACKS and does not have
> irqdomain support runs into:
>
> 	if (!d)
> 		bus->bus_flags |= PCI_BUS_FLAGS_NO_MSI;
>
> which in turn makes pci_msi_supported() return 0 and consequently makes
> pci_enable_msi[x]() fail.

I pointer that out in [1], together with a potential fix. Not sure if
anything else breaks though.

Thanks,

        M.

[1] 
https://lore.kernel.org/r/336d6588567949029c52ecfbb87660c1@xxxxxxxxxx/
--
Jazz is not dead. It just smells funny...