[PATCH 0/2] drm/bridge: it6505: DP audio support + shared-DAI hw_params fix

[PATCH 0/2] drm/bridge: it6505: DP audio support + shared-DAI hw_params fix

[Daniel Golle]

This revives Jiaxin Yu's stalled "drm/bridge: it6505: Add audio support"
v3 [1], rebased onto current mainline, plus the fix needed to make it work
on boards where the it6505 DP output shares an I2S DAI with another codec.

Patch 1 wires up the previously-unused it6505 audio helpers via
hdmi_codec_ops, which unblocks the mt8186-mt6366 sound card that
references it6505 as the I2S3 codec.

Patch 2 stops it6505_audio_setup_hw_params() from returning -ENODEV when
no DP display is attached, which would otherwise tear down the shared
backend and break playback on the co-located codec (the speaker).

Tested on a MediaTek MT8186 (google,steelix) Chromebook: speaker and
built-in mic work. Actual HDMI/DP audio output could not be tested as the
sample exposes no usable DP-audio port.

[1] https://lore.kernel.org/all/20230730180803.22570-4-jiaxin.yu@mediatek.com/
Daniel Golle (1):
  drm/bridge: it6505: Don't reject audio hw_params without an encoder

Jiaxin Yu (1):
  drm/bridge: it6505: Add audio support

 drivers/gpu/drm/bridge/ite-it6505.c | 94 +++++++++++++++++++++++------
 1 file changed, 77 insertions(+), 17 deletions(-)


base-commit: 0718283ab28bc3907e10b61a6b4be6fefa1cbb2f
prerequisite-patch-id: 0000000000000000000000000000000000000000
-- 
2.55.0

[PATCH 1/2] drm/bridge: it6505: Add audio support

[Daniel Golle]

From: Jiaxin Yu <jiaxin.yu@mediatek.com>

Add audio support for it6505 by bridging to the hdmi-codec, registering
an "hdmi-audio-codec" platform device from probe. The it6505's audio
setup/shutdown helpers were merged earlier as unused code; wire them up
via hdmi_codec_ops so the DAI actually appears, which unblocks the
mt8186-mt6366 sound card that references it6505 as the I2S3 codec.

Some DP-to-HDMI dongles get into a bad state if InfoFrame is sent
without audio data, so it6505's audio is only enabled once the stream
is unmuted.

[djg: respin of Jiaxin Yu's v3; rebased onto current tree; the driver
 gained it6505->dev so drop the &client->dev usages; hdmi_codec_ops no
 longer has .trigger, so enable/disable via .mute_stream instead; drop
 now-redundant __maybe_unused on the wired-up helpers]

Signed-off-by: Jiaxin Yu <jiaxin.yu@mediatek.com>
Link: https://lore.kernel.org/all/20230730180803.22570-4-jiaxin.yu@mediatek.com/
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
---
 drivers/gpu/drm/bridge/ite-it6505.c | 92 ++++++++++++++++++++++++-----
 1 file changed, 76 insertions(+), 16 deletions(-)

diff --git a/drivers/gpu/drm/bridge/ite-it6505.c b/drivers/gpu/drm/bridge/ite-it6505.c
index 8ecb43611dba..698ae01b3a47 100644
--- a/drivers/gpu/drm/bridge/ite-it6505.c
+++ b/drivers/gpu/drm/bridge/ite-it6505.c
@@ -2320,19 +2320,12 @@ static void it6505_stop_link_train(struct it6505 *it6505)
 
 static void it6505_link_train_ok(struct it6505 *it6505)
 {
-	struct device *dev = it6505->dev;
-
 	it6505->link_state = LINK_OK;
 	/* disalbe mute enable avi info frame */
 	it6505_set_bits(it6505, REG_DATA_MUTE_CTRL, EN_VID_MUTE, 0x00);
 	it6505_set_bits(it6505, REG_INFOFRAME_CTRL,
 			EN_VID_CTRL_PKT, EN_VID_CTRL_PKT);
 
-	if (it6505_audio_input(it6505)) {
-		DRM_DEV_DEBUG_DRIVER(dev, "Enable audio!");
-		it6505_enable_audio(it6505);
-	}
-
 	if (it6505->hdcp_desired)
 		it6505_start_hdcp(it6505);
 }
@@ -2960,7 +2953,7 @@ static void it6505_remove_notifier_module(struct it6505 *it6505)
 	}
 }
 
-static void __maybe_unused it6505_delayed_audio(struct work_struct *work)
+static void it6505_delayed_audio(struct work_struct *work)
 {
 	struct it6505 *it6505 = container_of(work, struct it6505,
 					     delayed_audio.work);
@@ -2974,9 +2967,9 @@ static void __maybe_unused it6505_delayed_audio(struct work_struct *work)
 		it6505_enable_audio(it6505);
 }
 
-static int __maybe_unused it6505_audio_setup_hw_params(struct it6505 *it6505,
-						       struct hdmi_codec_params
-						       *params)
+static int it6505_audio_setup_hw_params(struct it6505 *it6505,
+					struct hdmi_codec_params
+					*params)
 {
 	struct device *dev = it6505->dev;
 	int i = 0;
@@ -3031,7 +3024,7 @@ static int __maybe_unused it6505_audio_setup_hw_params(struct it6505 *it6505,
 	return 0;
 }
 
-static void __maybe_unused it6505_audio_shutdown(struct device *dev, void *data)
+static void it6505_audio_shutdown(struct device *dev, void *data)
 {
 	struct it6505 *it6505 = dev_get_drvdata(dev);
 
@@ -3039,10 +3032,40 @@ static void __maybe_unused it6505_audio_shutdown(struct device *dev, void *data)
 		it6505_disable_audio(it6505);
 }
 
-static int __maybe_unused it6505_audio_hook_plugged_cb(struct device *dev,
-						       void *data,
-						       hdmi_codec_plugged_cb fn,
-						       struct device *codec_dev)
+static int it6505_audio_hw_params(struct device *dev, void *data,
+				  struct hdmi_codec_daifmt *daifmt,
+				  struct hdmi_codec_params *params)
+{
+	struct it6505 *it6505 = dev_get_drvdata(dev);
+
+	return it6505_audio_setup_hw_params(it6505, params);
+}
+
+static int it6505_audio_mute(struct device *dev, void *data,
+			     bool enable, int direction)
+{
+	struct it6505 *it6505 = dev_get_drvdata(dev);
+
+	DRM_DEV_DEBUG_DRIVER(dev, "mute: %d", enable);
+
+	/*
+	 * Some DP-to-HDMI dongles get into a bad state if the InfoFrame is
+	 * sent without audio data, so only enable it6505's audio once the
+	 * stream is unmuted (i.e. actually playing).
+	 */
+	if (enable)
+		cancel_delayed_work(&it6505->delayed_audio);
+	else
+		queue_delayed_work(system_wq, &it6505->delayed_audio,
+				   msecs_to_jiffies(180));
+
+	return 0;
+}
+
+static int it6505_audio_hook_plugged_cb(struct device *dev,
+					void *data,
+					hdmi_codec_plugged_cb fn,
+					struct device *codec_dev)
 {
 	struct it6505 *it6505 = data;
 
@@ -3053,6 +3076,37 @@ static int __maybe_unused it6505_audio_hook_plugged_cb(struct device *dev,
 	return 0;
 }
 
+static const struct hdmi_codec_ops it6505_audio_codec_ops = {
+	.hw_params = it6505_audio_hw_params,
+	.mute_stream = it6505_audio_mute,
+	.audio_shutdown = it6505_audio_shutdown,
+	.hook_plugged_cb = it6505_audio_hook_plugged_cb,
+};
+
+static int it6505_register_audio_driver(struct device *dev)
+{
+	struct it6505 *it6505 = dev_get_drvdata(dev);
+	struct hdmi_codec_pdata codec_data = {
+		.ops = &it6505_audio_codec_ops,
+		.max_i2s_channels = 8,
+		.i2s = 1,
+		.no_capture_mute = 1,
+		.data = it6505,
+	};
+	struct platform_device *pdev;
+
+	pdev = platform_device_register_data(dev, HDMI_CODEC_DRV_NAME,
+					     PLATFORM_DEVID_AUTO, &codec_data,
+					     sizeof(codec_data));
+	if (IS_ERR(pdev))
+		return PTR_ERR(pdev);
+
+	INIT_DELAYED_WORK(&it6505->delayed_audio, it6505_delayed_audio);
+	DRM_DEV_DEBUG_DRIVER(dev, "bound to %s", HDMI_CODEC_DRV_NAME);
+
+	return 0;
+}
+
 static inline struct it6505 *bridge_to_it6505(struct drm_bridge *bridge)
 {
 	return container_of(bridge, struct it6505, bridge);
@@ -3612,6 +3666,12 @@ static int it6505_i2c_probe(struct i2c_client *client)
 		return err;
 	}
 
+	err = it6505_register_audio_driver(dev);
+	if (err < 0) {
+		dev_err(dev, "Failed to register audio driver: %d", err);
+		return err;
+	}
+
 	INIT_WORK(&it6505->link_works, it6505_link_training_work);
 	INIT_WORK(&it6505->hdcp_wait_ksv_list, it6505_hdcp_wait_ksv_list);
 	INIT_DELAYED_WORK(&it6505->hdcp_work, it6505_hdcp_work);
-- 
2.55.0

[PATCH 2/2] drm/bridge: it6505: Don't reject audio hw_params without an encoder

[Daniel Golle]

it6505_audio_setup_hw_params() returns -ENODEV when the bridge is not
attached to a DRM encoder. Now that it6505 registers an hdmi-audio-codec,
this callback runs whenever a stream is configured on the I2S DAI it is
wired to, including when that DAI is shared with another codec. On
mt8186-corsola the speaker amplifier (rt1019) and it6505 share I2S3, so
when the it6505 DP output has no display attached (bridge.encoder is
NULL) the -ENODEV propagates up through dpcm_be_dai_hw_params() and tears
down the whole backend, breaking speaker playback.

A codec must not fail hw_params on a shared DAI just because its own sink
is absent; the actual output is already gated by it6505->powered. Return
0 so the shared link can be configured.

Fixes: b5c84a9edcd4 ("drm/bridge: add it6505 driver")
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
---
 drivers/gpu/drm/bridge/ite-it6505.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/bridge/ite-it6505.c b/drivers/gpu/drm/bridge/ite-it6505.c
index 698ae01b3a47..e88960c82a23 100644
--- a/drivers/gpu/drm/bridge/ite-it6505.c
+++ b/drivers/gpu/drm/bridge/ite-it6505.c
@@ -2979,7 +2979,7 @@ static int it6505_audio_setup_hw_params(struct it6505 *it6505,
 			     params->cea.channels);
 
 	if (!it6505->bridge.encoder)
-		return -ENODEV;
+		return 0;
 
 	if (params->cea.channels <= 1 || params->cea.channels > 8) {
 		DRM_DEV_DEBUG_DRIVER(dev, "channel number: %d not support",
-- 
2.55.0