[PATCH v2 09/22] drm/nouveau: Lock/unlock DDC lines on probe

[Lukas Wunner]

On dual gpu laptops such as the MacBook Pro, ask vga_switcheroo to
switch the DDC lines to the Nvidia gpu before probing them.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=88861
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=61115
Tested-by: Paul Hordiienko <pvt.gord at gmail.com>
    [MBP  6,2 2010  intel ILK + nvidia GT216  pre-retina]
Tested-by: William Brown <william at blackhats.net.au>
    [MBP  8,2 2011  intel SNB + amd turks     pre-retina]
Tested-by: Lukas Wunner <lukas at wunner.de>
    [MBP  9,1 2012  intel IVB + nvidia GK107  pre-retina]
Tested-by: Bruno Bierbaumer <bruno at bierbaumer.net>
    [MBP 11,3 2013  intel HSW + nvidia GK107  retina -- work in progress]

Signed-off-by: Lukas Wunner <lukas at wunner.de>
---
 drivers/gpu/drm/nouveau/nouveau_connector.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_connector.c b/drivers/gpu/drm/nouveau/nouveau_connector.c
index 3162040..ad59eab 100644
--- a/drivers/gpu/drm/nouveau/nouveau_connector.c
+++ b/drivers/gpu/drm/nouveau/nouveau_connector.c
@@ -27,6 +27,7 @@
 #include <acpi/button.h>
 
 #include <linux/pm_runtime.h>
+#include <linux/vga_switcheroo.h>
 
 #include <drm/drmP.h>
 #include <drm/drm_edid.h>
@@ -148,7 +149,11 @@ nouveau_connector_ddc_detect(struct drm_connector *connector)
 				break;
 		} else
 		if (nv_encoder->i2c) {
-			if (nv_probe_i2c(nv_encoder->i2c, 0x50))
+			int ret;
+			vga_switcheroo_lock_ddc(dev->pdev);
+			ret = nv_probe_i2c(nv_encoder->i2c, 0x50);
+			vga_switcheroo_unlock_ddc(dev->pdev);
+			if (ret)
 				break;
 		}
 	}
-- 
1.8.5.2 (Apple Git-48)