Re: [PATCH v4 5/5] PCI: Handle Enhanced Allocation (EA) capability for bridges

On 10/05/2015 03:54 PM, Sean O. Stalley wrote:

On Fri, Oct 02, 2015 at 03:37:56PM -0700, David Daney wrote:

quoted

From: David Daney <redacted>

PCI bridges may have their properties be specified via EA entries.

Extend the EA parser to extract the bridge resources, and modify
pci_read_bridge_{io,mmio,mmio_pref}() to use resources previously
obtained via EA.

Save the offset to the EA capability in struct pci_dev, and use it to
easily find the EA bridge subordinate and secondary bus numbers.

When assigning the bridge resources a couple of changes are required
so that the EA obtained IORESOURCE_PCI_FIXED are not resized, and
correctly linked into the resource tree.

1) In pbus_size_mem() do not attempt to resize the bridge resources if
    they are marked as IORESOURCE_PCI_FIXED.

2) In pci_bus_alloc_from_region()for IORESOURCE_PCI_FIXED resources, just
    try to request the resource as is, without attempting to resize it.

Signed-off-by: David Daney <redacted>
---
  drivers/pci/bus.c       |  7 +++++++
  drivers/pci/pci.c       | 13 +++++++++++++
  drivers/pci/probe.c     | 31 +++++++++++++++++++++++++++++--
  drivers/pci/setup-bus.c |  3 +++
  include/linux/pci.h     |  1 +
  5 files changed, 53 insertions(+), 2 deletions(-)

@@ -801,8 +813,23 @@ int pci_scan_bridge(struct pci_bus *bus, struct pci_dev *dev, int max, int pass)

  	pci_read_config_dword(dev, PCI_PRIMARY_BUS, &buses);
  	primary = buses & 0xFF;
-	secondary = (buses >> 8) & 0xFF;
-	subordinate = (buses >> 16) & 0xFF;
+	if (dev->ea_cap) {
+		u32 dw1;
+
+		pci_read_config_dword(dev, dev->ea_cap + 4, &dw1);
+		if (dw1 & 0xFF)
+			secondary = dw1 & 0xFF;
+		else
+			secondary = (buses >> 8) & 0xFF;
+
+		if ((dw1 >> 8) & 0xFF)
+			subordinate = (dw1 >> 8) & 0xFF;
+		else
+			subordinate = (buses >> 16) & 0xFF;
+	} else {
+		secondary = (buses >> 8) & 0xFF;
+		subordinate = (buses >> 16) & 0xFF;
+	}

We can refactor this to make it cleaner/more compact. from V3 review:


	secondary = (buses >> 8) & 0xFF;
	subordinate = (buses >> 16) & 0xFF;
	if (dev->ea_cap) {
		u32 sdw;
		
		pci_read_config_dword(dev, dev->ea_cap + 4, &sdw);
		
		if (sdw & 0xFF)
			secondary = sdw & 0xFF;
		
		sdw >>= 8;
		if (sdw & 0xFF)
			subordinate = sdw & 0xFF;
	}

Yes, that is cleaner.  I think I didn't read the comments on v3 closely 
enough.  I will switch to doing it this way.

Thanks,
David Daney

-Sean