Re: [patch 2.5.31] transparent PCI-to-PCI bridges

Ivan Kokshaysky
2002-08-26T13:53:52Z

On Sun, Aug 25, 2002 at 06:55:59PM +0200, Manfred Spraul wrote:
> Why not
> if ((dev->class & 0xff) == 0x01)
>
> Is the lowest bit an indicator of subtractive decoding, or is
> Progif==0x01 the indicator of subtractive decoding?

The latter.

> The code and the comment should match.

Ok. Updated patch appended.

Ivan.

--- 2.5.31/arch/i386/pci/fixup.c Sun Aug 11 05:41:21 2002
+++ linux/arch/i386/pci/fixup.c Mon Aug 26 17:48:37 2002
@@ -166,6 +166,23 @@ static void __init pci_fixup_via_northbr
}
}

+/*
+ * For some weird reasons Intel decided that certain parts of their
+ * 815, 845 and some other chipsets must look like PCI-to-PCI bridges
+ * while they are obviously not. The 82801 family (AA, AB, BAM/CAM,
+ * BA/CA/DB and E) PCI bridges are actually HUB-to-PCI ones, according
+ * to Intel terminology. These devices do forward all addresses from
+ * system to PCI bus no matter what are their window settings, so they are
+ * "transparent" (or subtractive decoding) from programmers point of view.
+ * Indicate this by setting ProgIf to 0x01.
+ */
+static void __init pci_fixup_transparent_bridge(struct pci_dev *dev)
+{
+ if ((dev->class >> 8) == PCI_CLASS_BRIDGE_PCI &&
+ (dev->device & 0xff00) == 0x2400)
+ dev->class = (dev->class & ~0xff) | 1;
+}
+
struct pci_fixup pcibios_fixups[] = {
{ PCI_FIXUP_HEADER, PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_82451NX, pci_fixup_i450nx },
{ PCI_FIXUP_HEADER, PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_82454GX, pci_fixup_i450gx },
@@ -183,5 +200,6 @@ struct pci_fixup pcibios_fixups[] = {
{ PCI_FIXUP_HEADER, PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_8361, pci_fixup_via_northbridge_bug },
{ PCI_FIXUP_HEADER, PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_8367_0, pci_fixup_via_northbridge_bug },
{ PCI_FIXUP_HEADER, PCI_VENDOR_ID_NCR, PCI_DEVICE_ID_NCR_53C810, pci_fixup_ncr53c810 },
+ { PCI_FIXUP_HEADER, PCI_VENDOR_ID_INTEL, PCI_ANY_ID, pci_fixup_transparent_bridge },
{ 0 }
};
--- 2.5.31/drivers/pci/quirks.c Sun Aug 11 05:41:17 2002
+++ linux/drivers/pci/quirks.c Mon Aug 26 17:50:16 2002
@@ -471,6 +471,11 @@ static void __init quirk_dunord ( struct
r -> end = 0xffffff;
}

+static void __init quirk_transparent_bridge(struct pci_dev *dev)
+{
+ dev->class = (dev->class & ~0xff) | 1;
+}
+
/*
* The main table of quirks.
*/
@@ -525,6 +530,12 @@ static struct pci_fixup pci_fixups[] __i

{ PCI_FIXUP_FINAL, PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_VIPER_7410, quirk_amd_ioapic },
{ PCI_FIXUP_FINAL, PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_FE_GATE_700C, quirk_amd_ordering },
+ /*
+ * i82380FB mobile docking controller: its PCI-to-PCI bridge
+ * is subtractive decoding (transparent), and does indicate this
+ * in the ProgIf. Unfortunately, in the wrong bit - 7 instead of 0.
+ */
+ { PCI_FIXUP_HEADER, PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_82380FB, quirk_transparent_bridge },

{ 0 }
};
--- 2.5.31/drivers/pci/probe.c Sun Aug 11 05:41:21 2002
+++ linux/drivers/pci/probe.c Mon Aug 26 17:38:51 2002
@@ -128,6 +128,18 @@ void __devinit pci_read_bridge_bases(str
if (!dev) /* It's a host bus, nothing to read */
return;

+ /*
+ * The PCI-to-PCI bridge spec requires that subtractive decoding
+ * (i.e. transparent) bridge must have programming interface code
+ * of 0x01.
+ */
+ if ((dev->class & 0xff) == 0x01) {
+ printk("Transparent bridge - %s\n", dev->name);
+ for(i = 0; i < 3; i++)
+ child->resource[i] = child->parent->resource[i];
+ return;
+ }
+
for(i=0; i<3; i++)
child->resource[i] = &dev->resource[PCI_BRIDGE_RESOURCES+i];

@@ -149,13 +161,6 @@ void __devinit pci_read_bridge_bases(str
res->flags = (io_base_lo & PCI_IO_RANGE_TYPE_MASK) | IORESOURCE_IO;
res->start = base;
res->end = limit + 0xfff;
- } else {
- /*
- * Ugh. We don't know enough about this bridge. Just assume
- * that it's entirely transparent.
- */
- printk(KERN_ERR "Unknown bridge resource %d: assuming transparent\n", 0);
- child->resource[0] = child->parent->resource[0];
}

res = child->resource[1];
@@ -167,10 +172,6 @@ void __devinit pci_read_bridge_bases(str
res->flags = (mem_base_lo & PCI_MEMORY_RANGE_TYPE_MASK) | IORESOURCE_MEM;
res->start = base;
res->end = limit + 0xfffff;
- } else {
- /* See comment above. Same thing */
- printk(KERN_ERR "Unknown bridge resource %d: assuming transparent\n", 1);
- child->resource[1] = child->parent->resource[1];
}

res = child->resource[2];
@@ -197,10 +198,6 @@ void __devinit pci_read_bridge_bases(str
res->flags = (mem_base_lo & PCI_MEMORY_RANGE_TYPE_MASK) | IORESOURCE_MEM | IORESOURCE_PREFETCH;
res->start = base;
res->end = limit + 0xfffff;
- } else {
- /* See comments above */
- printk(KERN_ERR "Unknown bridge resource %d: assuming transparent\n", 2);
- child->resource[2] = child->parent->resource[2];
}
}