diff options
Diffstat (limited to 'drivers/gpu/drm/i915/intel_i2c.c')
| -rw-r--r-- | drivers/gpu/drm/i915/intel_i2c.c | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/intel_i2c.c b/drivers/gpu/drm/i915/intel_i2c.c index c7eab724c418..b94acc4cc05f 100644 --- a/drivers/gpu/drm/i915/intel_i2c.c +++ b/drivers/gpu/drm/i915/intel_i2c.c @@ -118,6 +118,23 @@ static void set_data(void *data, int state_high) udelay(I2C_RISEFALL_TIME); /* wait for the line to change state */ } +/* Clears the GMBUS setup. Our driver doesn't make use of the GMBUS I2C + * engine, but if the BIOS leaves it enabled, then that can break our use + * of the bit-banging I2C interfaces. This is notably the case with the + * Mac Mini in EFI mode. + */ +void +intel_i2c_reset_gmbus(struct drm_device *dev) +{ + struct drm_i915_private *dev_priv = dev->dev_private; + + if (IS_IGDNG(dev)) { + I915_WRITE(PCH_GMBUS0, 0); + } else { + I915_WRITE(GMBUS0, 0); + } +} + /** * intel_i2c_create - instantiate an Intel i2c bus using the specified GPIO reg * @dev: DRM device @@ -168,6 +185,8 @@ struct i2c_adapter *intel_i2c_create(struct drm_device *dev, const u32 reg, if(i2c_bit_add_bus(&chan->adapter)) goto out_free; + intel_i2c_reset_gmbus(dev); + /* JJJ: raise SCL and SDA? */ intel_i2c_quirk_set(dev, true); set_data(chan, 1); |