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Commit a70b95c0 authored by Stephen Kitt's avatar Stephen Kitt Committed by Dave Airlie
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agp: ensure GART has an address before enabling it 

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 96576a9e ("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: default avatarStephen 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>
Cc: <stable@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarDave Airlie <airlied@redhat.com>
parent cecd1455

drivers/char/agp/intel-agp.c

+16 −11
Original line number Original line Diff line number Diff line
@@ -773,21 +773,15 @@ static int __devinit agp_intel_probe(struct pci_dev *pdev, 




	dev_info(&pdev->dev, "Intel %s Chipset\n", intel_agp_chipsets[i].name);

	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

	* The following fixes the case where the BIOS has "forgotten" to

	* provide an address range for the GART.

	* provide an address range for the GART.

	* 20030610 - hamish@zot.org

	* 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];

	r = &pdev->resource[0];

	if (!r->start && r->end) {

	if (!r->start && r->end) {
@@ -798,6 +792,17 @@ static int __devinit agp_intel_probe(struct pci_dev *pdev, 
		}

		}

	}

	}





	/*

	* 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 */

	/* Fill in the mode register */

	if (cap_ptr) {

	if (cap_ptr) {

		pci_read_config_dword(pdev,

		pci_read_config_dword(pdev,