dm: pci: Enable VGA address forwarding on bridges
To support graphics card behind a PCI bridge, the bridge control
register (offset 0x3e) in the configuration space must turn on
VGA address forwarding.
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/pci/pci-uclass.c b/drivers/pci/pci-uclass.c
index d15de5a..1d93194 100644
--- a/drivers/pci/pci-uclass.c
+++ b/drivers/pci/pci-uclass.c
@@ -364,9 +364,23 @@
return 0;
}
+static void set_vga_bridge_bits(struct udevice *dev)
+{
+ struct udevice *parent = dev->parent;
+ u16 bc;
+
+ while (parent->seq != 0) {
+ dm_pci_read_config16(parent, PCI_BRIDGE_CONTROL, &bc);
+ bc |= PCI_BRIDGE_CTL_VGA;
+ dm_pci_write_config16(parent, PCI_BRIDGE_CONTROL, bc);
+ parent = parent->parent;
+ }
+}
+
int pci_auto_config_devices(struct udevice *bus)
{
struct pci_controller *hose = bus->uclass_priv;
+ struct pci_child_platdata *pplat;
unsigned int sub_bus;
struct udevice *dev;
int ret;
@@ -386,6 +400,10 @@
return ret;
max_bus = ret;
sub_bus = max(sub_bus, max_bus);
+
+ pplat = dev_get_parent_platdata(dev);
+ if (pplat->class == (PCI_CLASS_DISPLAY_VGA << 8))
+ set_vga_bridge_bits(dev);
}
debug("%s: done\n", __func__);