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[v4,4/6] drm/i915: Switch DDC when reading the EDID

Message ID 1f339369f889faa455ced90d68773e860cf93b1a.1444670070.git.lukas@wunner.de (mailing list archive)
State New, archived
Headers show

Commit Message

Lukas Wunner Sept. 11, 2015, 10:40 a.m. UTC
The pre-retina MacBook Pro uses an LVDS panel and a gmux controller
to switch the panel between its two GPUs. The panel mode in VBIOS
is notoriously bogus on these machines and some models have no
VBIOS at all.

Use drm_get_edid_switcheroo() in lieu of drm_get_edid() on LVDS.
This allows us to retrieve the EDID if the outputs are currently
muxed to the discrete GPU by temporarily switching the panel's DDC
lines to the integrated GPU.

This only enables EDID probing on the pre-retina MBP (2008 - 2013).
The retina MBP (2012 - present) uses eDP and gmux is not capable
of switching AUX separately from the main link on these models.
This will be addressed in later patches.

List of pre-retina MBPs with dual GPUs, one of them Intel:
    [MBP  6,2 2010  intel ILK + nvidia GT216  pre-retina  15"]
    [MBP  6,1 2010  intel ILK + nvidia GT216  pre-retina  17"]
    [MBP  8,2 2011  intel SNB + amd turks     pre-retina  15"]
    [MBP  8,3 2011  intel SNB + amd turks     pre-retina  17"]
    [MBP  9,1 2012  intel IVB + nvidia GK107  pre-retina  15"]

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=88861
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=61115
Tested-by: William Brown <william@blackhats.net.au>
    [MBP  8,2 2011  intel SNB + amd turks     pre-retina  15"]
Tested-by: Lukas Wunner <lukas@wunner.de>
    [MBP  9,1 2012  intel IVB + nvidia GK107  pre-retina  15"]

Signed-off-by: Lukas Wunner <lukas@wunner.de>
---
 drivers/gpu/drm/i915/intel_lvds.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
diff mbox

Patch

diff --git a/drivers/gpu/drm/i915/intel_lvds.c b/drivers/gpu/drm/i915/intel_lvds.c
index 881b5d1..a84727f 100644
--- a/drivers/gpu/drm/i915/intel_lvds.c
+++ b/drivers/gpu/drm/i915/intel_lvds.c
@@ -1067,7 +1067,8 @@  void intel_lvds_init(struct drm_device *dev)
 	 * preferred mode is the right one.
 	 */
 	mutex_lock(&dev->mode_config.mutex);
-	edid = drm_get_edid(connector, intel_gmbus_get_adapter(dev_priv, pin));
+	edid = drm_get_edid_switcheroo(connector,
+				       intel_gmbus_get_adapter(dev_priv, pin));
 	if (edid) {
 		if (drm_add_edid_modes(connector, edid)) {
 			drm_mode_connector_update_edid_property(connector,