[coreboot-gerrit] Change in coreboot[master]: device/pci: fix legacy VGA encoding

[Michael Niewöhner (Code Review)]

Michael Niewöhner has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/35514 )

Change subject: device/pci: fix legacy VGA encoding
......................................................................

device/pci: fix legacy VGA encoding

Enable decoding of 16-bit legacy VGA addresses to prevent resource
conflicts with other devices (like SMBus and SATA on X11SS* boards).

Tested on X11SSM-F.

Change-Id: I29e37ac69d68ef8e0f37ef02660a53101f254992
Signed-off-by: Michael Niewöhner 
---
M src/device/cardbus_device.c
M src/device/device.c
M src/include/device/pci_def.h
3 files changed, 18 insertions(+), 4 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/14/35514/1

diff --git a/src/device/cardbus_device.c b/src/device/cardbus_device.c
index a440746..4cd9f85 100644
--- a/src/device/cardbus_device.c
+++ b/src/device/cardbus_device.c
@@ -156,6 +156,7 @@
    		PCI_BRIDGE_CTL_SERR |
    		PCI_BRIDGE_CTL_NO_ISA |
    		PCI_BRIDGE_CTL_VGA |
+			PCI_BRIDGE_CTL_VGA16 |
    		PCI_BRIDGE_CTL_MASTER_ABORT |
    		PCI_BRIDGE_CTL_BUS_RESET));
    /* Error check */
diff --git a/src/device/device.c b/src/device/device.c
index 44d1f95..d0806ea 100644
--- a/src/device/device.c
+++ b/src/device/device.c
@@ -19,6 +19,7 @@
 #include <device/device.h>
 #include <device/pci_def.h>
 #include <device/pci_ids.h>
+#include <device/pci_ops.h>
 #include <stdlib.h>
 #include <string.h>
 #include <smp/spinlock.h>
@@ -748,6 +749,7 @@
    /* FIXME: Handle the VGA palette snooping. */
    struct device *dev, *vga, *vga_onboard;
    struct bus *bus;
+	u16 ctrl;

bus = 0;
    vga = 0;
@@ -793,11 +795,21 @@
    	bus = vga->bus;
    }

-	/* Now walk up the bridges setting the VGA enable. */
+	/* Now walk up the bridges setting the VGA enable if supported. */
    while (bus) {
-		printk(BIOS_DEBUG, "Setting PCI_BRIDGE_CTL_VGA for bridge %s\n",
-		       dev_path(bus->dev));
-		bus->bridge_ctrl |= PCI_BRIDGE_CTL_VGA;
+		/* try to set VGA16; it will return 1 if it is supported */
+		ctrl = pci_read_config16(bus->dev, PCI_CB_BRIDGE_CONTROL);
+		if (!(ctrl & PCI_BRIDGE_CTL_VGA16)) {  // no test needed if already set
+			pci_or_config16(bus->dev, PCI_CB_BRIDGE_CONTROL, PCI_BRIDGE_CTL_VGA16);
+			ctrl = pci_read_config16(bus->dev, PCI_CB_BRIDGE_CONTROL);
+			/* restore */
+			pci_write_config16(bus->dev, PCI_CB_BRIDGE_CONTROL, ctrl & ~PCI_BRIDGE_CTL_VGA16);
+		}
+		if (ctrl & PCI_BRIDGE_CTL_VGA16) {
+			printk(BIOS_DEBUG, "Setting PCI_BRIDGE_CTL_VGA(16) for bridge %s\n", dev_path(bus->dev));
+			bus->bridge_ctrl |= (PCI_BRIDGE_CTL_VGA | PCI_BRIDGE_CTL_VGA16);
+		}
+
    	bus = (bus == bus->dev->bus) ? 0 : bus->dev->bus;
    }
 }
diff --git a/src/include/device/pci_def.h b/src/include/device/pci_def.h
index bc5bc79..660edcb 100644
--- a/src/include/device/pci_def.h
+++ b/src/include/device/pci_def.h
@@ -138,6 +138,7 @@
 #define  PCI_BRIDGE_CTL_SERR	0x02	/* The same for SERR forwarding */
 #define  PCI_BRIDGE_CTL_NO_ISA	0x04	/* Disable bridging of ISA ports */
 #define  PCI_BRIDGE_CTL_VGA	0x08	/* Forward VGA addresses */
+#define  PCI_BRIDGE_CTL_VGA16	0x16	/* Enable VGA16 decoding */
 #define  PCI_BRIDGE_CTL_MASTER_ABORT 0x20  /* Report master aborts */
 #define  PCI_BRIDGE_CTL_BUS_RESET 0x40	/* Secondary bus reset */
 /* Fast Back2Back enabled on secondary interface */