[PATCH 1/1] drm/i915: ensure i2c adapter is all set before adding it

Jani Nikula
2012-08-13T14:33:02Z

i2c_add_adapter() may do i2c transfers on the bus to detect supported
devices. Therefore the adapter needs to be all set before adding it. This
was not the case for the bit-banging fallback, resulting in an oops if the
device detection GMBUS transfers timed out. Fix the issue by calling
i2c_add_adapter() only after intel_gpio_setup().

LKML-Reference: <5021F00B.7000503@ionic.de>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
---
drivers/gpu/drm/i915/intel_i2c.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_i2c.c b/drivers/gpu/drm/i915/intel_i2c.c
index 1991a44..a23ba84f 100644
--- a/drivers/gpu/drm/i915/intel_i2c.c
+++ b/drivers/gpu/drm/i915/intel_i2c.c
@@ -486,9 +486,6 @@ int intel_setup_gmbus(struct drm_device *dev)
bus->dev_priv = dev_priv;

bus->adapter.algo = &gmbus_algorithm;
- ret = i2c_add_adapter(&bus->adapter);
- if (ret)
- goto err;

/* By default use a conservative clock rate */
bus->reg0 = port | GMBUS_RATE_100KHZ;
@@ -498,6 +495,10 @@ int intel_setup_gmbus(struct drm_device *dev)
bus->force_bit = true;

intel_gpio_setup(bus, port);
+
+ ret = i2c_add_adapter(&bus->adapter);
+ if (ret)
+ goto err;
}

intel_i2c_reset(dev_priv->dev);
--
1.7.9.5