drm/i915/audio: do not mess with audio registers if port is invalid

We should no longer enter the codec enable/disable functions in question
with port A anyway, but to err on the safe side, keep the warnings. Just
bail out early without messing with the registers.
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Sivakumar Thulasimani <sivakumar.thulasimani@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_audio.c

@@ -269,6 +269,9 @@ static void ilk_audio_codec_disable(struct intel_encoder *encoder)
 	DRM_DEBUG_KMS("Disable audio codec on port %c, pipe %c\n",
 		      port_name(port), pipe_name(pipe));
 
+	if (WARN_ON(port == PORT_A))
+		return;
+
 	if (HAS_PCH_IBX(dev_priv->dev)) {
 		aud_config = IBX_AUD_CFG(pipe);
 		aud_cntrl_st2 = IBX_AUD_CNTL_ST2;
@@ -290,12 +293,7 @@ static void ilk_audio_codec_disable(struct intel_encoder *encoder)
 		tmp |= AUD_CONFIG_N_VALUE_INDEX;
 	I915_WRITE(aud_config, tmp);
 
-	if (WARN_ON(!port)) {
-		eldv = IBX_ELD_VALID(PORT_B) | IBX_ELD_VALID(PORT_C) |
-			IBX_ELD_VALID(PORT_D);
-	} else {
 	eldv = IBX_ELD_VALID(port);
-	}
 
 	/* Invalidate ELD */
 	tmp = I915_READ(aud_cntrl_st2);
@@ -325,6 +323,9 @@ static void ilk_audio_codec_enable(struct drm_connector *connector,
 	DRM_DEBUG_KMS("Enable audio codec on port %c, pipe %c, %u bytes ELD\n",
 		      port_name(port), pipe_name(pipe), drm_eld_size(eld));
 
+	if (WARN_ON(port == PORT_A))
+		return;
+
 	/*
 	 * FIXME: We're supposed to wait for vblank here, but we have vblanks
 	 * disabled during the mode set. The proper fix would be to push the
@@ -349,12 +350,7 @@ static void ilk_audio_codec_enable(struct drm_connector *connector,
 		aud_cntrl_st2 = CPT_AUD_CNTRL_ST2;
 	}
 
-	if (WARN_ON(!port)) {
-		eldv = IBX_ELD_VALID(PORT_B) | IBX_ELD_VALID(PORT_C) |
-			IBX_ELD_VALID(PORT_D);
-	} else {
 	eldv = IBX_ELD_VALID(port);
-	}
 
 	/* Invalidate ELD */
 	tmp = I915_READ(aud_cntrl_st2);