drm/vc4: hdmi: Skip writes to disabled packet RAM

This path actually occurs when audio is started during a hdmi mode set.
As the data will be written by vc4_hdmi_set_infoframes when packet RAM
is enabled again, don't treat as an error
Signed-off-by: Dom Cobley <popcornmix@gmail.com>
Link: https://lore.kernel.org/r/20220613144800.326124-26-maxime@cerno.techSigned-off-by: Maxime Ripard <maxime@cerno.tech>

drivers/gpu/drm/vc4/vc4_hdmi.c

@@ -602,7 +602,9 @@ static void vc4_hdmi_set_audio_infoframe(struct drm_encoder *encoder)
 	union hdmi_infoframe frame;
 
 	memcpy(&frame.audio, audio, sizeof(*audio));
-	vc4_hdmi_write_infoframe(encoder, &frame);
+
+	if (vc4_hdmi->packet_ram_enabled)
+		vc4_hdmi_write_infoframe(encoder, &frame);
 }
 
 static void vc4_hdmi_set_hdr_infoframe(struct drm_encoder *encoder)
@@ -742,6 +744,8 @@ static void vc4_hdmi_encoder_post_crtc_disable(struct drm_encoder *encoder,
 
 	mutex_lock(&vc4_hdmi->mutex);
 
+	vc4_hdmi->packet_ram_enabled = false;
+
 	spin_lock_irqsave(&vc4_hdmi->hw_lock, flags);
 
 	HDMI_WRITE(HDMI_RAM_PACKET_CONFIG, 0);
@@ -1352,6 +1356,7 @@ static void vc4_hdmi_encoder_post_crtc_enable(struct drm_encoder *encoder,
 			   VC4_HDMI_RAM_PACKET_ENABLE);
 
 		spin_unlock_irqrestore(&vc4_hdmi->hw_lock, flags);
+		vc4_hdmi->packet_ram_enabled = true;
 
 		vc4_hdmi_set_infoframes(encoder);
 	}

drivers/gpu/drm/vc4/vc4_hdmi.h

@@ -212,6 +212,12 @@ struct vc4_hdmi {
 	 */
 	struct drm_display_mode saved_adjusted_mode;
 
+	/**
+	 * @packet_ram_enabled: Is the HDMI controller packet RAM currently
+	 * on? Protected by @mutex.
+	 */
+	bool packet_ram_enabled;
+
 	/**
 	 * @scdc_enabled: Is the HDMI controller currently running with
 	 * the scrambler on? Protected by @mutex.