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

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@amd.com>
Cc: stable@vger.kernel.org
Acked-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>

diff --git a/drivers/gpu/drm/radeon/radeon_i2c.c b/drivers/gpu/drm/radeon/radeon_i2c.c
index 85bcfc8923a789bf73101a1c5ef7cadc9ec1300f..3edec1c198e3145addb0b47bbafdf3cf2abd1e49 100644 (file)
--- 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;