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i945/gma.c: Only init LVDS if it is detected 

Some devices have no LVDS output but if no VGA is connected or
no EDID can be found, it will try to init LVDS.

This patch detects the presence of an LVDS panel and makes sure that
LVDS is not initialized when it is absent.

Change-Id: Ie15631514535bab6c881c1f52e9edbfb8aaa5db7
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/16513
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Martin Roth <martinroth@google.com>
This commit is contained in:
Arthur Heymans 2016-09-06 23:53:32 +02:00 committed by Martin Roth
parent 4aa295ca28
commit 62f4dad88d
1 changed files with 9 additions and 5 deletions
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14
src/northbridge/intel/i945/gma.c
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@ -557,18 +557,20 @@ static int intel_gma_init_vga(struct northbridge_intel_i945_config *conf,
/* compare the header of the vga edid header */
/* if vga is not connected it should have a correct header */
static int vga_connected(u8 *pmmio) {
static int probe_edid(u8 *pmmio, u8 slave)
{
u8 vga_edid[128];
u8 header[8] = {0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00};
intel_gmbus_read_edid(pmmio + GMBUS0, 2, 0x50, vga_edid, 128);
intel_gmbus_read_edid(pmmio + GMBUS0, slave, 0x50, vga_edid, 128);
intel_gmbus_stop(pmmio + GMBUS0);
for (int i = 0; i < 8; i++) {
if (vga_edid[i] != header[i]) {
printk(BIOS_DEBUG, "VGA not connected. Using LVDS display\n");
printk(BIOS_DEBUG, "No display connected on slave %d\n",
slave);
return 0;
}
}
printk(BIOS_SPEW, "VGA display connected\n");
printk(BIOS_SPEW, "Found a display on slave %d\n", slave);
return 1;
}
@ -613,7 +615,9 @@ static void gma_func0_init(struct device *dev)
);
int err;
if (vga_connected(mmiobase))
/* probe if VGA is connected and alway run */
/* VGA init if no LVDS is connected */
if (!probe_edid(mmiobase, 3) || probe_edid(mmiobase, 2))
err = intel_gma_init_vga(conf, pci_read_config32(dev, 0x5c) & ~0xf,
iobase, mmiobase, graphics_base);
else