Patch "x86/PCI: Use host bridge _CRS info on systems with >32 bit addressing" has been added to the 4.1-stable tree

This is a note to let you know that I've just added the patch titled

x86/PCI: Use host bridge _CRS info on systems with >32 bit addressing

to the 4.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
x86-pci-use-host-bridge-_crs-info-on-systems-with-32-bit-addressing.patch
and it can be found in the queue-4.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Bjorn Helgaas <[email protected]>
Date: Tue, 9 Jun 2015 17:31:38 -0500
Subject: x86/PCI: Use host bridge _CRS info on systems with >32 bit addressing

From: Bjorn Helgaas <[email protected]>

commit 3d9fecf6bfb8b12bc2f9a4c7109895a2a2bb9436 upstream.

We enable _CRS on all systems from 2008 and later. On older systems, we ignore _CRS and assume the whole physical address space (excluding RAM and other devices) is available for PCI devices, but on systems that support physical address spaces larger than 4GB, it's doubtful that the area above 4GB is really available for PCI.

After d56dbf5bab8c ("PCI: Allocate 64-bit BARs above 4G when possible"), we try to use that space above 4GB *first*, so we're more likely to put a device there.

On Juan's Toshiba Satellite Pro U200, BIOS left the graphics, sound, 1394, and card reader devices unassigned (but only after Windows had been booted). Only the sound device had a 64-bit BAR, so it was the only device placed above 4GB, and hence the only device that didn't work.

Keep _CRS enabled even on pre-2008 systems if they support physical address space larger than 4GB.

---
 arch/x86/pci/acpi.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

@@ -121,8 +121,10 @@ void __init pci_acpi_crs_quirks(void)
 {
 	int year;
 
-	if (dmi_get_date(DMI_BIOS_DATE, &year, NULL, NULL) && year < 2008)
-		pci_use_crs = false;
+	if (dmi_get_date(DMI_BIOS_DATE, &year, NULL, NULL) && year < 2008) {
+		if (iomem_resource.end <= 0xffffffff)
+			pci_use_crs = false;
+	}
 
 	dmi_check_system(pci_crs_quirks);
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.1/x86-pci-use-host-bridge-_crs-info-on-systems-with-32-bit-addressing.patch queue-4.1/x86-pci-use-host-bridge-_crs-info-on-foxconn-k8m890-8237a.patch