Re: PCI IO resource question.

[Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>]

On Thu, Mar 17, 2016 at 05:28:31PM -0400, Murali Karicheri wrote:

[...]

> > The only ways I see that PCI_PROBE_ONLY can be set on ARM are if you have
> > "linux,pci-probe-only" in your DT or you boot with "pci=firmware".
> > 
> > I expect you're in this path:
> > 
> >   ahci_init_one
> >     pcim_enable_device
> >       pci_enable_device
> >         pci_enable_device_flags(dev, IORESOURCE_MEM | IORESOURCE_IO)
> >           # build "bars" mask
> >           do_pci_enable_device(dev, bars)
> >             pcibios_enable_device
> >               if (pci_has_flag(PCI_PROBE_ONLY))
> >                 return 0;
> >               pci_enable_resources
> > 
> > Can you add a little debug code like this to verify that we're in this
> > path?
> 
> Yes we are in the path.
> 
> 
> [    1.557561] ahci_init_one
> [    1.560214] ahci 0000:01:00.0: version 3.0
> [    1.564302] pcim_enable_device
> [    1.567349] pci_enable_device
> [    1.570340] pci_enable_device_flags
> [    1.573824] do_pci_enable_device
> [    1.577042] pcibios_enable_device
> [    1.580380] pci_enable_resources

So resources are actually enabled (ie PCI_PROBE_ONLY is not set)
and that makes sense otherwise you would not be able to use the
MEM resources anyway (ie they would not be enabled).

I suspect the PCI dev IO resources were reset in reset_resource() in
assign_requested_resource_sorted(), hence the bar mask that is built
in pci_enable_device_flags() does not contain the IO resources,
it would be helpful if you can print the bar mask passed to
pcibios_enable_device() (ie the mask parameter).

Not saying that's what should happen, I think that's what's happening,
that's the only reason I see why you do not have pci_enable_resources()
failures when you remove the IO range from the host bridge.

Lorenzo

> [    1.583608] ahci 0000:01:00.0: limiting MRRS to 256
> [    1.588595] ahci 0000:01:00.0: AHCI 0001.0000 32 slots 2 ports 6 Gbps 0x3 impl SATA mode
> [    1.596716] ahci 0000:01:00.0: flags: 64bit ncq sntf led only pmp fbs pio slum part sxs 
> [    1.606183] scsi host0: ahci
> [    1.609448] scsi host1: ahci
> [    1.612636] ata1: SATA max UDMA/133 abar m512@0x60000000 port 0x60000100 irq 82
> [    1.619974] ata2: SATA max UDMA/133 abar m512@0x60000000 port 0x60000180 irq 82
> 
> > 
> >> I looked at pci_enable_resources()
> >>
> >> 	for (i = 0; i < PCI_NUM_RESOURCES; i++) {
> >> 		if (!(mask & (1 << i)))
> >> 			continue;
> >>
> >> 		r = &dev->resource[i];
> > 
> >                 dev_info(&dev->dev, "BAR %d %pR mask %#04x parent %p\n", i, r, mask, r->parent);
> > 
> >>
> >> 		if (!(r->flags & (IORESOURCE_IO | IORESOURCE_MEM)))
> >> 			continue;
> >> 		if ((i == PCI_ROM_RESOURCE) &&
> >> 				(!(r->flags & IORESOURCE_ROM_ENABLE)))
> >> 			continue;
> >>
> >> 		if (r->flags & IORESOURCE_UNSET) {
> >> 			dev_err(&dev->dev, "can't enable device: BAR %d %pR not assigned\n",
> >> 				i, r);
> >> 			return -EINVAL;
> >> 		}
> >>
> >> 		if (!r->parent) {
> >> 			dev_err(&dev->dev, "can't enable device: BAR %d %pR not claimed\n",
> >> 				i, r);
> >> 			return -EINVAL;
> >> 		}
> >>
> >> I don't see the error "can't enable device: BAR %d %pR not assigned" , so it doesn't
> >> depend on IO bar as you mention below or is it in a different function?
> > 
> 
> 
> -- 
> Murali Karicheri
> Linux Kernel, Keystone
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