drm/i915: HDMI hot remove notification to audio driver

On HDMI monitor hot remove, clear SDVO_AUDIO_ENABLE accordingly, so that
the audio driver will receive hot plug events and take action to refresh
its device state and ELD contents.

The cleared SDVO_AUDIO_ENABLE bit needs to be restored to prevent losing
HDMI audio after DPMS on.

CC: Wang Zhenyu <zhenyu.z.wang@intel.com>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Keith Packard <keithp@keithp.com>

drivers/gpu/drm/i915/intel_hdmi.c

@@ -269,6 +269,10 @@ static void intel_hdmi_dpms(struct drm_encoder *encoder, int mode)
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct intel_hdmi *intel_hdmi = enc_to_intel_hdmi(encoder);
 	u32 temp;
+	u32 enable_bits = SDVO_ENABLE;
+
+	if (intel_hdmi->has_audio)
+		enable_bits |= SDVO_AUDIO_ENABLE;
 
 	temp = I915_READ(intel_hdmi->sdvox_reg);
 
@@ -281,9 +285,9 @@ static void intel_hdmi_dpms(struct drm_encoder *encoder, int mode)
 	}
 
 	if (mode != DRM_MODE_DPMS_ON) {
-		temp &= ~SDVO_ENABLE;
+		temp &= ~enable_bits;
 	} else {
-		temp |= SDVO_ENABLE;
+		temp |= enable_bits;
 	}
 
 	I915_WRITE(intel_hdmi->sdvox_reg, temp);