drm/vc4: hdmi: Stop checking for enabled output in audio

The current HDMI driver, in vc4_hdmi_audio_can_stream() checks whether
the display output is enabled.

This has been there in one form or the other since the introduction of
the audio support in the VC4 HDMI driver in commit bb7d7856
("drm/vc4: Add HDMI audio support"), but no justification for this check
is in the commit message, or in the discussions around the patches.

One can only assume this was done to prevent a user from playing audio
on the ALSA soundcard when the monitor doesn't support it.

However, this is causing some issues. Indeed, Kodi, for example, was
hitting some errors if it was streaming audio during a modeset. With the
theory above, it does make sense, but the display and audio threads are
typically completely different processes with no opportunity to
synchronise which makes it hard to workaround.

Removing that check also doesn't seem to cause any trouble, so let's
just remove it.
Signed-off-by: Dom Cobley <popcornmix@gmail.com>
Link: https://lore.kernel.org/r/20220613144800.326124-25-maxime@cerno.techSigned-off-by: Maxime Ripard <maxime@cerno.tech>

drivers/gpu/drm/vc4/vc4_hdmi.c

@@ -789,15 +789,6 @@ static void vc4_hdmi_encoder_post_crtc_powerdown(struct drm_encoder *encoder,
 	mutex_unlock(&vc4_hdmi->mutex);
 }
 
-static void vc4_hdmi_encoder_disable(struct drm_encoder *encoder)
-{
-	struct vc4_hdmi *vc4_hdmi = encoder_to_vc4_hdmi(encoder);
-
-	mutex_lock(&vc4_hdmi->mutex);
-	vc4_hdmi->output_enabled = false;
-	mutex_unlock(&vc4_hdmi->mutex);
-}
-
 static void vc4_hdmi_csc_setup(struct vc4_hdmi *vc4_hdmi,
 			       struct drm_connector_state *state,
 			       const struct drm_display_mode *mode)
@@ -1371,15 +1362,6 @@ static void vc4_hdmi_encoder_post_crtc_enable(struct drm_encoder *encoder,
 	mutex_unlock(&vc4_hdmi->mutex);
 }
 
-static void vc4_hdmi_encoder_enable(struct drm_encoder *encoder)
-{
-	struct vc4_hdmi *vc4_hdmi = encoder_to_vc4_hdmi(encoder);
-
-	mutex_lock(&vc4_hdmi->mutex);
-	vc4_hdmi->output_enabled = true;
-	mutex_unlock(&vc4_hdmi->mutex);
-}
-
 static void vc4_hdmi_encoder_atomic_mode_set(struct drm_encoder *encoder,
 					     struct drm_crtc_state *crtc_state,
 					     struct drm_connector_state *conn_state)
@@ -1673,8 +1655,6 @@ static const struct drm_encoder_helper_funcs vc4_hdmi_encoder_helper_funcs = {
 	.atomic_check = vc4_hdmi_encoder_atomic_check,
 	.atomic_mode_set = vc4_hdmi_encoder_atomic_mode_set,
 	.mode_valid = vc4_hdmi_encoder_mode_valid,
-	.disable = vc4_hdmi_encoder_disable,
-	.enable = vc4_hdmi_encoder_enable,
 };
 
 static u32 vc4_hdmi_channel_map(struct vc4_hdmi *vc4_hdmi, u32 channel_mask)
@@ -1771,19 +1751,15 @@ static inline struct vc4_hdmi *dai_to_hdmi(struct snd_soc_dai *dai)
 
 static bool vc4_hdmi_audio_can_stream(struct vc4_hdmi *vc4_hdmi)
 {
-	lockdep_assert_held(&vc4_hdmi->mutex);
+	struct drm_display_info *display = &vc4_hdmi->connector.display_info;
 
-	/*
-	 * If the controller is disabled, prevent any ALSA output.
-	 */
-	if (!vc4_hdmi->output_enabled)
-		return false;
+	lockdep_assert_held(&vc4_hdmi->mutex);
 
 	/*
 	 * If the encoder is currently in DVI mode, treat the codec DAI
 	 * as missing.
 	 */
-	if (!(HDMI_READ(HDMI_RAM_PACKET_CONFIG) & VC4_HDMI_RAM_PACKET_ENABLE))
+	if (!display->is_hdmi)
 		return false;
 
 	return true;

drivers/gpu/drm/vc4/vc4_hdmi.h

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