[PATCH 2/2][Quantal] drm/nv50-/gpio: initialise to vbios defaults during init

[Seth Forshee]

From: Ben Skeggs <bskeggs at redhat.com>

This is required to fix an issue on the Retina MBP where the eDP panel's
AUX channel isn't wired up to the HPD pin for the panel, causing our aux
code to bail out early.

>From looking at various traces of the binary driver, it appears NVIDIA do
something very similar on at least all nv50+ chipsets during their
initialisation sequence.  So, hopefully this is safe.

Issue and fix initially tracked down by Ryan Bourgeois on fdo#51971.

Backported fix from reworked nouveau kernel module.

Signed-off-by: Ben Skeggs <bskeggs at redhat.com>
(cherry picked from commit 991083ba60f89e717e3a4175be96d48a810e9eae)
BugLink: http://bugs.launchpad.net/bugs/1058088
Signed-off-by: Seth Forshee <seth.forshee at canonical.com>
---
 drivers/gpu/drm/nouveau/nv50_gpio.c |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/nouveau/nv50_gpio.c b/drivers/gpu/drm/nouveau/nv50_gpio.c
index f429e6a..f034905 100644
--- a/drivers/gpu/drm/nouveau/nv50_gpio.c
+++ b/drivers/gpu/drm/nouveau/nv50_gpio.c
@@ -115,6 +115,9 @@ nv50_gpio_init(struct drm_device *dev)
 {
 	struct drm_nouveau_private *dev_priv = dev->dev_private;
 
+	/* initialise gpios and routing to vbios defaults */
+	nouveau_gpio_reset(dev);
+
 	/* disable, and ack any pending gpio interrupts */
 	nv_wr32(dev, 0xe050, 0x00000000);
 	nv_wr32(dev, 0xe054, 0xffffffff);
-- 
1.7.9.5