[PATCH] drm/radeon: only add the mm i2c bus if the hw_i2c module param is set

[alexdeucher at gmail.com]

From: Alex Deucher <alexander.deucher at amd.com>

It seems it can corrupt the monitor EDID in certain cases on certain
boards when running sensors detect.  It's rarely used anyway outside
of AIW boards.

http://lists.lm-sensors.org/pipermail/lm-sensors/2012-April/035847.html
http://lists.freedesktop.org/archives/xorg/2011-January/052239.html

Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
Cc: stable at vger.kernel.org
Cc: Jean Delvare <khali at linux-fr.org>
---
 drivers/gpu/drm/radeon/radeon_i2c.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/drivers/gpu/drm/radeon/radeon_i2c.c b/drivers/gpu/drm/radeon/radeon_i2c.c
index 85bcfc8..3edec1c 100644
--- a/drivers/gpu/drm/radeon/radeon_i2c.c
+++ b/drivers/gpu/drm/radeon/radeon_i2c.c
@@ -900,6 +900,10 @@ struct radeon_i2c_chan *radeon_i2c_create(struct drm_device *dev,
 	struct radeon_i2c_chan *i2c;
 	int ret;
 
+	/* don't add the mm_i2c bus unless hw_i2c is enabled */
+	if (rec->mm_i2c && (radeon_hw_i2c == 0))
+		return NULL;
+
 	i2c = kzalloc(sizeof(struct radeon_i2c_chan), GFP_KERNEL);
 	if (i2c == NULL)
 		return NULL;
-- 
1.7.7.5