[coreboot] New patch to review for coreboot: 6e5272a ASROCK Fam14 DSDT: Add secondary bus range to PCI0

Mike Loptien (mike.loptien@se-eng.com) gerrit at coreboot.org
Fri Mar 15 18:22:59 CET 2013

Mike Loptien (mike.loptien at se-eng.com) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/2736


commit 6e5272af247e5b379a8b17c997c0a86605bcabb2
Author: Mike Loptien <mike.loptien at se-eng.com>
Date:   Fri Mar 15 11:11:12 2013 -0600

    ASROCK Fam14 DSDT: Add secondary bus range to PCI0
    Adding the 'WordBusNumber' macro to the PCI0
    CRES ResourceTemplate in the Persimmon DSDT.
    This sets up the bus number for the PCI0 device
    and the secondary bus number in the CRS method.
    This change came in response to a 'dmesg' error
    which states:
    '[FIRMWARE BUG]: ACPI: no secondary bus range in _CRS'
    By adding the 'WordBusNumber' macro, ACPI can set
    up a valid range for the PCIe downstream busses,
    thereby relieving the Linux kernel from "guessing"
    the valid range based off _BBN or assuming [0-0xFF].
    The Linux kernel code that checks this bus range is
    in `drivers/acpi/pci_root.c`.  PCI busses can have
    up to 256 secondary busses connected to them via
    a PCI-PCI bridge.  However, these busses do not
    have to be sequentially numbered, so leaving out a
    section of the range (eg. allowing [0-0x7F]) will
    unnecessarily restrict the downstream busses.
    This is the same change as made to Persimmon with
    change-id I44f22:
    Change-Id: I5184df8deb7b5d2e15404d689c16c00493eb01aa
    Signed-off-by: Mike Loptien <mike.loptien at se-eng.com>
 src/mainboard/asrock/e350m1/dsdt.asl | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/src/mainboard/asrock/e350m1/dsdt.asl b/src/mainboard/asrock/e350m1/dsdt.asl
index bc45435..473092f 100644
--- a/src/mainboard/asrock/e350m1/dsdt.asl
+++ b/src/mainboard/asrock/e350m1/dsdt.asl
@@ -1477,6 +1477,22 @@ DefinitionBlock (
 			} /* end Ac97modem */
 			Name(CRES, ResourceTemplate() {
+				/* Set the Bus number and Secondary Bus number for the PCI0 device
+				 * The Secondary bus range for PCI0 lets the system
+				 * know what bus values are allowed on the downstream
+				 * side of this PCI bus if there is a PCI-PCI bridge.
+				 * PCI busses can have 256 secondary busses which
+				 * range from [0-0xFF] but they do not need to be
+				 * sequential.
+				 */
+				WordBusNumber (ResourceProducer, MinFixed, MaxFixed, PosDecode,
+					0x0000,		/* address granularity */
+					0x0000,		/* range minimum */
+					0x00FF,		/* range maximum */
+					0x0000,		/* translation */
+					0x0100,		/* length */
+					,, PSB0)	/* ResourceSourceIndex, ResourceSource, DescriptorName */
 				IO(Decode16, 0x0CF8, 0x0CF8, 1,	8)
 				WORDIO(ResourceProducer, MinFixed, MaxFixed, PosDecode, EntireRange,

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