[coreboot-gerrit] New patch to review for coreboot: nb/intel/gm45: Clear GTT correctly for IOMMU (igd)

[Damien Zammit (damien@zamaudio.com)]

Damien Zammit (damien at zamaudio.com) just uploaded a new patch set to gerrit, which you can find at https://review.coreboot.org/17645

-gerrit

commit 8684bf8685a58fcc13792d1d6cf3a6c706677d14
Author: Damien Zammit <damien at zamaudio.com>
Date:   Wed Nov 30 14:32:20 2016 +1100

    nb/intel/gm45: Clear GTT correctly for IOMMU (igd)
    
    Bit 11 of BDF(0,0,0), GGC(0x52) is actually the correct bit
    for detecting VT mode on IGD, not bit 10, according to
    GM45 Intel chipset datasheet.
    
    Now we use the correct bit for detecting VT mode on IGD.
    
    UNTESTED ON HW.
    
    Change-Id: I60268072619253443a04e61c9617f2260d5a750c
    Signed-off-by: Damien Zammit <damien at zamaudio.com>
---
 src/northbridge/intel/gm45/iommu.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/northbridge/intel/gm45/iommu.c b/src/northbridge/intel/gm45/iommu.c
index 77aba94..76432fb 100644
--- a/src/northbridge/intel/gm45/iommu.c
+++ b/src/northbridge/intel/gm45/iommu.c
@@ -46,8 +46,8 @@ void init_iommu()
 	MCHBAR32(0x20) = IOMMU_BASE4 | 1; /* all other DMA sources */
 
 	/* clear GTT */
-	u32 gtt = pci_read_config16(PCI_DEV(0, 0, 0), 0x52);
-	if (gtt & 0x400) { /* VT mode */
+	u16 ggc = pci_read_config16(PCI_DEV(0, 0, 0), D0F0_GGC);
+	if (ggc & 0x800) { /* VT mode */
 		pci_devfn_t igd = PCI_DEV(0, 2, 0);
 
 		/* setup somewhere */