From 589d604bf94ac7bd516772c9ee98afc800713680 Mon Sep 17 00:00:00 2001 From: John Baldwin Date: Fri, 16 Jan 2009 22:22:30 +0000 Subject: [PATCH] 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 --- sys/dev/pci/pci.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/sys/dev/pci/pci.c b/sys/dev/pci/pci.c index 295e68d9730..a027e9948e5 100644 --- a/sys/dev/pci/pci.c +++ b/sys/dev/pci/pci.c @@ -2291,9 +2291,27 @@ pci_add_map(device_t pcib, device_t bus, device_t dev, 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;