[+cc Lorenzo, since he takes care of this now]
On Tue, Jan 09, 2018 at 05:49:18PM +0100, Thomas Petazzoni wrote:
> Hello Bjorn,
>
> Again, reviving this very old thread :-)
>
> On Thu, 5 Oct 2017 12:23:30 -0500, Bjorn Helgaas wrote:
>
> > > - if (PCI_SLOT(devfn) != 0) {
> > > + if ((bus->number == pcie->root_bus_nr) && (PCI_SLOT(devfn) != 0)) {
> >
> > I'm fine with this, but please take a look at these:
> >
> > 8e7ca8ca5fd8 PCI: xilinx: Relax device number checking to allow SR-IOV
> > e18934b5e9c7 PCI: designware: Relax device number checking to allow SR-IOV
> > d99e30b7936a PCI: altera: Relax device number checking to allow SR-IOV
> >
> > and make sure that reasoning doesn't apply here, too.
> >
> > http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=8e7ca8ca5fd8
> > http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=e18934b5e9c7
> > http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=d99e30b7936a
>
> The original code for xilinx/designware/altera was doing:
>
> if (bus->number == port->root_busno && devfn > 0)
> return false;
>
> if (bus->primary == port->root_busno && devfn > 0)
> return false;
>
> I.e, it was checking both if bus->number *and* bus->primary were equal
> to port->root_busno.
>
> The commit you points removed the check on bus->primary, keeping the
> check on bus->number.
>
> Your patch for the Aadvark driver only adds a check on bus->number, i.e
> exactly what the xilinx/designware/altera code is still doing today:
This is a long time ago and I could have forgotten, but I don't think
this is *my* patch, is it?
> Altera:
>
> /* access only one slot on each root port */
> if (bus->number == pcie->root_bus_nr && dev > 0)
> return false;
>
> Designware:
>
> /* access only one slot on each root port */
> if (bus->number == pp->root_bus_nr && dev > 0)
> return 0;
>
> Xilinx:
>
> /* Only one device down on each root port */
> if (bus->number == port->root_busno && devfn > 0)
> return false;
>
> Aardvark (with our patch):
>
> if ((bus->number == pcie->root_bus_nr) && (PCI_SLOT(devfn) != 0)) {
> *val = 0xffffffff;
> return PCIBIOS_DEVICE_NOT_FOUND;
> }
>
> So we're doing exactly the same thing.
>
> Do you agree ?
I do agree. I can't remember what I was thinking when I first
responded.
I *would* suggest making an advk_pcie_valid_device() so your structure
matches the other drivers. I know it seems trivial when you're mostly
looking at one driver, but it really helps those who pay attention to
all of them.
Bjorn
