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Subject[patch 172/176] agp: ensure GART has an address before enabling it
2.6.36-stable review patch.  If anyone has any objections, please let us know.

------------------
From: Stephen Kitt <steve@sk2.org>

commit a70b95c017e8b518e1e069853355e4e497453dbb upstream.

Some BIOSs (eg. the AMI BIOS on the Asus P4P800 motherboard) don't
initialise the GART address, and pcibios_assign_resources() can ignore it
because it can be marked as a host bridge (see
https://bugzilla.kernel.org/show_bug.cgi?id=24392#c5 for details). This
was handled correctly up to 2.6.35, but the pci_enable_device() cleanup in
2.6.36 96576a9e1a0cdb8 ("agp: intel-agp: do not use PCI resources before
pci_enable_device()") means that the kernel tries to enable the GART
before assigning it an address; in such cases the GART overlaps with other
device assignments and ends up being disabled.

This patch fixes https://bugzilla.kernel.org/show_bug.cgi?id=24392

Note that I imagine efficeon-agp.c probably has the same problem, but
I can't test that and I'd like to make sure this patch is suitable for
-stable (since 2.6.36 and 2.6.37 are affected).

Signed-off-by: Stephen Kitt <steve@sk2.org>
Cc: Bjorn Helgaas <bjorn.helgaas@hp.com>
Cc: Maciej Rutecki <maciej.rutecki@gmail.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Kulikov Vasiliy <segooon@gmail.com>
Cc: Florian Mickler <florian@mickler.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/char/agp/intel-agp.c | 27 ++++++++++++++++-----------
1 file changed, 16 insertions(+), 11 deletions(-)
--- a/drivers/char/agp/intel-agp.c
+++ b/drivers/char/agp/intel-agp.c
@@ -927,20 +927,14 @@ static int __devinit agp_intel_probe(str
dev_info(&pdev->dev, "Intel %s Chipset\n", intel_agp_chipsets[i].name);

/*
- * If the device has not been properly setup, the following will catch
- * the problem and should stop the system from crashing.
- * 20030610 - hamish@zot.org
- */
- if (pci_enable_device(pdev)) {
- dev_err(&pdev->dev, "can't enable PCI device\n");
- agp_put_bridge(bridge);
- return -ENODEV;
- }
-
- /*
* The following fixes the case where the BIOS has "forgotten" to
* provide an address range for the GART.
* 20030610 - hamish@zot.org
+ * This happens before pci_enable_device() intentionally;
+ * calling pci_enable_device() before assigning the resource
+ * will result in the GART being disabled on machines with such
+ * BIOSs (the GART ends up with a BAR starting at 0, which
+ * conflicts a lot of other devices).
*/
r = &pdev->resource[0];
if (!r->start && r->end) {
@@ -951,6 +945,17 @@ static int __devinit agp_intel_probe(str
}
}

+ /*
+ * If the device has not been properly setup, the following will catch
+ * the problem and should stop the system from crashing.
+ * 20030610 - hamish@zot.org
+ */
+ if (pci_enable_device(pdev)) {
+ dev_err(&pdev->dev, "can't enable PCI device\n");
+ agp_put_bridge(bridge);
+ return -ENODEV;
+ }
+
/* Fill in the mode register */
if (cap_ptr) {
pci_read_config_dword(pdev,



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