svn commit: r187348 - head/sys/dev/pci
John Baldwin
jhb at FreeBSD.org
Fri Jan 16 14:22:31 PST 2009
Author: jhb
Date: Fri Jan 16 22:22:30 2009
New Revision: 187348
URL: http://svn.freebsd.org/changeset/base/187348
Log:
Disable decoding of BARs by devices before we trash the value in the BAR
by writing all 1's to it to determine its length. This fixes issues with
MCFG on at least some machines where a trashed BAR claimed subsequent
attempts at PCI config transactions because the addresses in the MCFG
window fell in the decoding range of the BAR.
In general it is a bad idea to leave the BARs enabled while we are
frobbing with them in this manner.
Sleuthing by: tegge
MFC after: 1 week
Modified:
head/sys/dev/pci/pci.c
Modified: head/sys/dev/pci/pci.c
==============================================================================
--- head/sys/dev/pci/pci.c Fri Jan 16 22:16:54 2009 (r187347)
+++ head/sys/dev/pci/pci.c Fri Jan 16 22:22:30 2009 (r187348)
@@ -2291,9 +2291,27 @@ pci_add_map(device_t pcib, device_t bus,
struct resource *res;
map = PCIB_READ_CONFIG(pcib, b, s, f, reg, 4);
+
+ /*
+ * Disable decoding via the command register before
+ * determining the BARs length since we will be placing them
+ * in a weird state.
+ */
+ cmd = PCIB_READ_CONFIG(pcib, b, s, f, PCIR_COMMAND, 2);
+ PCIB_WRITE_CONFIG(pcib, b, s, f, PCIR_COMMAND,
+ cmd & ~(PCI_BAR_MEM(map) ? PCIM_CMD_MEMEN : PCIM_CMD_PORTEN), 2);
+
+ /*
+ * Determine the BAR's length by writing all 1's. The bottom
+ * log_2(size) bits of the BAR will stick as 0 when we read
+ * the value back.
+ */
PCIB_WRITE_CONFIG(pcib, b, s, f, reg, 0xffffffff, 4);
testval = PCIB_READ_CONFIG(pcib, b, s, f, reg, 4);
+
+ /* Restore the BAR and command register. */
PCIB_WRITE_CONFIG(pcib, b, s, f, reg, map, 4);
+ PCIB_WRITE_CONFIG(pcib, b, s, f, PCIR_COMMAND, cmd, 2);
if (PCI_BAR_MEM(map))
type = SYS_RES_MEMORY;
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