[PATCH 10/10] drm/bridge: synopsys: dw-dp: Add audio support
Sebastian Reichel
sebastian.reichel at collabora.com
Thu Mar 26 10:31:34 PDT 2026
Implement audio support for the Synopsys DesignWare DisplayPort
controller.
Signed-off-by: Sebastian Reichel <sebastian.reichel at collabora.com>
---
drivers/gpu/drm/bridge/synopsys/dw-dp.c | 197 +++++++++++++++++++++++++++++++-
1 file changed, 196 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/bridge/synopsys/dw-dp.c b/drivers/gpu/drm/bridge/synopsys/dw-dp.c
index 9ee9e3b9d912..add22acea719 100644
--- a/drivers/gpu/drm/bridge/synopsys/dw-dp.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-dp.c
@@ -23,17 +23,21 @@
#include <drm/drm_bridge.h>
#include <drm/drm_bridge_connector.h>
#include <drm/display/drm_dp_helper.h>
+#include <drm/display/drm_hdmi_audio_helper.h>
#include <drm/drm_edid.h>
#include <drm/drm_of.h>
#include <drm/drm_print.h>
#include <drm/drm_probe_helper.h>
#include <drm/drm_simple_kms_helper.h>
+#include <sound/hdmi-codec.h>
+
#define DW_DP_VERSION_NUMBER 0x0000
#define DW_DP_VERSION_TYPE 0x0004
#define DW_DP_ID 0x0008
#define DW_DP_CONFIG_REG1 0x0100
+#define AUDIO_SELECT GENMASK(2, 1)
#define DW_DP_CONFIG_REG2 0x0104
#define DW_DP_CONFIG_REG3 0x0108
@@ -110,6 +114,10 @@
#define HBR_MODE_ENABLE BIT(10)
#define AUDIO_DATA_WIDTH GENMASK(9, 5)
#define AUDIO_DATA_IN_EN GENMASK(4, 1)
+#define AUDIO_DATA_IN_EN_CHANNEL12 BIT(0)
+#define AUDIO_DATA_IN_EN_CHANNEL34 BIT(1)
+#define AUDIO_DATA_IN_EN_CHANNEL56 BIT(2)
+#define AUDIO_DATA_IN_EN_CHANNEL78 BIT(3)
#define AUDIO_INF_SELECT BIT(0)
#define DW_DP_SDP_VERTICAL_CTRL 0x0500
@@ -253,6 +261,8 @@
#define SDP_REG_BANK_SIZE 16
+#define DW_DP_SDP_VERSION 0x12
+
struct dw_dp_link_caps {
bool enhanced_framing;
bool tps3_supported;
@@ -305,6 +315,19 @@ struct dw_dp_hotplug {
bool long_hpd;
};
+enum dw_dp_audio_interface_support {
+ DW_DP_AUDIO_I2S_ONLY = 0,
+ DW_DP_AUDIO_SPDIF_ONLY = 1,
+ DW_DP_AUDIO_I2S_AND_SPDIF = 2,
+ DW_DP_AUDIO_NONE = 3,
+};
+
+enum dw_dp_audio_interface {
+ DW_DP_AUDIO_I2S = 0,
+ DW_DP_AUDIO_SPDIF = 1,
+ DW_DP_AUDIO_UNUSED,
+};
+
struct dw_dp {
struct drm_bridge bridge;
struct device *dev;
@@ -320,6 +343,8 @@ struct dw_dp {
int irq;
struct work_struct hpd_work;
struct dw_dp_hotplug hotplug;
+ enum dw_dp_audio_interface audio_interface;
+ int audio_channels;
/* Serialize hpd status access */
struct mutex irq_lock;
@@ -1844,6 +1869,163 @@ static void dw_dp_bridge_oob_notify(struct drm_bridge *bridge,
dev_err_once(dp->dev, "Missing platform handler for OOB HPD handling\n");
}
+static int dw_dp_audio_infoframe_send(struct dw_dp *dp)
+{
+ struct hdmi_audio_infoframe frame;
+ struct dw_dp_sdp sdp;
+ int ret;
+
+ ret = hdmi_audio_infoframe_init(&frame);
+ if (ret < 0)
+ return ret;
+
+ frame.coding_type = HDMI_AUDIO_CODING_TYPE_STREAM;
+ frame.sample_frequency = HDMI_AUDIO_SAMPLE_FREQUENCY_STREAM;
+ frame.sample_size = HDMI_AUDIO_SAMPLE_SIZE_STREAM;
+ frame.channels = dp->audio_channels;
+
+ ret = hdmi_audio_infoframe_pack_for_dp(&frame, &sdp.base, DW_DP_SDP_VERSION);
+ if (ret < 0)
+ return ret;
+
+ sdp.flags = DW_DP_SDP_VERTICAL_INTERVAL;
+
+ return dw_dp_send_sdp(dp, &sdp);
+}
+
+static int dw_dp_audio_prepare(struct drm_bridge *bridge,
+ struct drm_connector *connector,
+ struct hdmi_codec_daifmt *daifmt,
+ struct hdmi_codec_params *params)
+{
+ struct dw_dp *dp = bridge_to_dp(bridge);
+ u8 audio_data_in_en, supported_audio_interfaces;
+ u32 cfg1;
+ int ret;
+
+ pm_runtime_get_sync(dp->dev);
+
+ dp->audio_channels = params->cea.channels;
+ switch (params->cea.channels) {
+ case 1:
+ case 2:
+ audio_data_in_en = AUDIO_DATA_IN_EN_CHANNEL12;
+ break;
+ case 8:
+ audio_data_in_en = AUDIO_DATA_IN_EN_CHANNEL12 |
+ AUDIO_DATA_IN_EN_CHANNEL34 |
+ AUDIO_DATA_IN_EN_CHANNEL56 |
+ AUDIO_DATA_IN_EN_CHANNEL78;
+ break;
+ default:
+ dev_err(dp->dev, "invalid audio channels %d\n", dp->audio_channels);
+ return -EINVAL;
+ }
+
+ switch (daifmt->fmt) {
+ case HDMI_SPDIF:
+ dp->audio_interface = DW_DP_AUDIO_SPDIF;
+ break;
+ case HDMI_I2S:
+ /*
+ * It is recommended to use SPDIF instead of I2S, since I2S mode requires
+ * manually inserting PCUV control bits from userspace and this is done
+ * automatically in hardware for SPDIF mode.
+ */
+ dp->audio_interface = DW_DP_AUDIO_I2S;
+ break;
+ default:
+ dev_err(dp->dev, "invalid DAI format %d\n", daifmt->fmt);
+ return -EINVAL;
+ }
+
+ regmap_read(dp->regmap, DW_DP_CONFIG_REG1, &cfg1);
+ supported_audio_interfaces = FIELD_GET(AUDIO_SELECT, cfg1);
+
+ if (supported_audio_interfaces != DW_DP_AUDIO_I2S_AND_SPDIF &&
+ supported_audio_interfaces != dp->audio_interface) {
+ dev_err(dp->dev, "unsupported DAI %d\n", daifmt->fmt);
+ return -EINVAL;
+ }
+
+ clk_prepare_enable(dp->spdif_clk);
+ clk_prepare_enable(dp->i2s_clk);
+
+ regmap_update_bits(dp->regmap, DW_DP_AUD_CONFIG1,
+ AUDIO_DATA_IN_EN | NUM_CHANNELS | AUDIO_DATA_WIDTH |
+ AUDIO_INF_SELECT | HBR_MODE_ENABLE,
+ FIELD_PREP(AUDIO_DATA_IN_EN, audio_data_in_en) |
+ FIELD_PREP(NUM_CHANNELS, dp->audio_channels - 1) |
+ FIELD_PREP(AUDIO_DATA_WIDTH, params->sample_width) |
+ FIELD_PREP(AUDIO_INF_SELECT, dp->audio_interface) |
+ FIELD_PREP(HBR_MODE_ENABLE, 0));
+
+ /* Wait for inf switch */
+ usleep_range(20, 40);
+
+ if (dp->audio_interface == DW_DP_AUDIO_I2S)
+ clk_disable_unprepare(dp->spdif_clk);
+ else if (dp->audio_interface == DW_DP_AUDIO_SPDIF)
+ clk_disable_unprepare(dp->i2s_clk);
+
+ /*
+ * Send audio stream during vertical and horizontal blanking periods.
+ * Send out audio timestamp SDP once per video frame during the vertical
+ * blanking period
+ */
+ regmap_update_bits(dp->regmap, DW_DP_SDP_VERTICAL_CTRL,
+ EN_AUDIO_STREAM_SDP | EN_AUDIO_TIMESTAMP_SDP,
+ FIELD_PREP(EN_AUDIO_STREAM_SDP, 1) |
+ FIELD_PREP(EN_AUDIO_TIMESTAMP_SDP, 1));
+ regmap_update_bits(dp->regmap, DW_DP_SDP_HORIZONTAL_CTRL,
+ EN_AUDIO_STREAM_SDP,
+ FIELD_PREP(EN_AUDIO_STREAM_SDP, 1));
+
+ ret = dw_dp_audio_infoframe_send(dp);
+ if (ret < 0)
+ dev_err(dp->dev, "failed to send audio infoframe\n");
+
+ dev_dbg(dp->dev, "audio start with %d channels using DAI=%d\n",
+ dp->audio_channels, dp->audio_interface);
+
+ return 0;
+}
+
+static void dw_dp_audio_shutdown(struct drm_bridge *bridge,
+ struct drm_connector *connector)
+{
+ struct dw_dp *dp = bridge_to_dp(bridge);
+
+ dev_dbg(dp->dev, "audio shutdown\n");
+
+ /* Disable all audio streams */
+ regmap_update_bits(dp->regmap, DW_DP_AUD_CONFIG1, AUDIO_DATA_IN_EN,
+ FIELD_PREP(AUDIO_DATA_IN_EN, 0));
+
+ if (dp->audio_interface == DW_DP_AUDIO_SPDIF)
+ clk_disable_unprepare(dp->spdif_clk);
+ else if (dp->audio_interface == DW_DP_AUDIO_I2S)
+ clk_disable_unprepare(dp->i2s_clk);
+
+ dp->audio_interface = DW_DP_AUDIO_UNUSED;
+
+ pm_runtime_put_autosuspend(dp->dev);
+}
+
+static int dw_dp_audio_mute_stream(struct drm_bridge *bridge,
+ struct drm_connector *connector,
+ bool enable, int direction)
+{
+ struct dw_dp *dp = bridge_to_dp(bridge);
+
+ dev_dbg(dp->dev, "audio %smute\n", enable ? "" : "un");
+
+ regmap_update_bits(dp->regmap, DW_DP_AUD_CONFIG1, AUDIO_MUTE,
+ FIELD_PREP(AUDIO_MUTE, enable));
+
+ return 0;
+}
+
static const struct drm_bridge_funcs dw_dp_bridge_funcs = {
.atomic_duplicate_state = dw_dp_bridge_atomic_duplicate_state,
.atomic_destroy_state = drm_atomic_helper_bridge_destroy_state,
@@ -1858,6 +2040,10 @@ static const struct drm_bridge_funcs dw_dp_bridge_funcs = {
.edid_read = dw_dp_bridge_edid_read,
.detach = dw_dp_bridge_detach,
.oob_notify = dw_dp_bridge_oob_notify,
+
+ .dp_audio_prepare = dw_dp_audio_prepare,
+ .dp_audio_shutdown = dw_dp_audio_shutdown,
+ .dp_audio_mute_stream = dw_dp_audio_mute_stream,
};
static int dw_dp_link_retrain(struct dw_dp *dp)
@@ -2084,10 +2270,19 @@ struct dw_dp *dw_dp_bind(struct device *dev, struct drm_encoder *encoder,
}
bridge->of_node = dev->of_node;
- bridge->ops = DRM_BRIDGE_OP_DETECT | DRM_BRIDGE_OP_EDID | DRM_BRIDGE_OP_HPD;
+ bridge->ops = DRM_BRIDGE_OP_DP_AUDIO |
+ DRM_BRIDGE_OP_DETECT |
+ DRM_BRIDGE_OP_EDID |
+ DRM_BRIDGE_OP_HPD;
bridge->type = DRM_MODE_CONNECTOR_DisplayPort;
bridge->ycbcr_420_allowed = true;
+ dp->audio_interface = DW_DP_AUDIO_UNUSED;
+ bridge->hdmi_audio_dev = dev;
+ bridge->hdmi_audio_max_i2s_playback_channels = 8;
+ bridge->hdmi_audio_dai_port = 1;
+ bridge->hdmi_audio_spdif_playback = true;
+
ret = devm_drm_bridge_add(dev, bridge);
if (ret)
return ERR_PTR(ret);
--
2.53.0
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