drm/i915/sdvo: restore i2c adapter config on intel_sdvo_init() failures

SDVOB may be multiplexed with HDMIB. If it's not SDVOB, the same i2c
adapter may be used for HDMIB, with the adjusted config (i.e. with GPIO
bit-banging instead of gmbus). Restore i2c adapter config before error
return from intel_sdvo_init(), letting HDMIB enjoy the joys of gmbus.
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_sdvo.c

@@ -2055,6 +2055,13 @@ intel_sdvo_select_i2c_bus(struct drm_i915_private *dev_priv,
 	intel_gmbus_force_bit(sdvo->i2c, true);
 }
 
+/* undo any changes intel_sdvo_select_i2c_bus() did to sdvo->i2c */
+static void
+intel_sdvo_unselect_i2c_bus(struct intel_sdvo *sdvo)
+{
+	intel_gmbus_force_bit(sdvo->i2c, false);
+}
+
 static bool
 intel_sdvo_is_hdmi_connector(struct intel_sdvo *intel_sdvo, int device)
 {
@@ -2630,10 +2637,8 @@ bool intel_sdvo_init(struct drm_device *dev, uint32_t sdvo_reg, bool is_sdvob)
 	intel_sdvo->is_sdvob = is_sdvob;
 	intel_sdvo->slave_addr = intel_sdvo_get_slave_addr(dev, intel_sdvo) >> 1;
 	intel_sdvo_select_i2c_bus(dev_priv, intel_sdvo, sdvo_reg);
-	if (!intel_sdvo_init_ddc_proxy(intel_sdvo, dev)) {
-		kfree(intel_sdvo);
-		return false;
-	}
+	if (!intel_sdvo_init_ddc_proxy(intel_sdvo, dev))
+		goto err_i2c_bus;
 
 	/* encoder type will be decided later */
 	intel_encoder = &intel_sdvo->base;
@@ -2718,6 +2723,8 @@ bool intel_sdvo_init(struct drm_device *dev, uint32_t sdvo_reg, bool is_sdvob)
 err:
 	drm_encoder_cleanup(&intel_encoder->base);
 	i2c_del_adapter(&intel_sdvo->ddc);
+err_i2c_bus:
+	intel_sdvo_unselect_i2c_bus(intel_sdvo);
 	kfree(intel_sdvo);
 
 	return false;