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dm: pci: Enable VGA address forwarding on bridges

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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>
This commit is contained in:
Bin Meng 2015-10-01 00:36:02 -07:00 committed by Simon Glass
parent 069155cbb4
commit bbbcb52628
1 changed files with 18 additions and 0 deletions
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18
drivers/pci/pci-uclass.c
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@ -364,9 +364,23 @@ int dm_pci_read_config32(struct udevice *dev, int offset, u32 *valuep)
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 @@ int pci_auto_config_devices(struct udevice *bus)
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__);