Re: [PATCH 2/2] drm/bridge: lt8912b: Add support for audio

[Dmitry Baryshkov]

On Mon, Feb 03, 2025 at 04:23:56PM -0300, rafael@xxxxxxxx wrote:
> From: Rafael Beims <rafael.beims@xxxxxxxxxxx>
> 
> Add support for HDMI codec with audio coming from the I2S input.
> Support 48kHz and 96kHz sample rate, with 16 bits word size.
> 
> Co-developed-by: João Paulo Gonçalves <joao.goncalves@xxxxxxxxxxx>
> Signed-off-by: João Paulo Gonçalves <joao.goncalves@xxxxxxxxxxx>
> Signed-off-by: Rafael Beims <rafael.beims@xxxxxxxxxxx>

Please turn the bridge to support DRM_BRIDGE_OP_HDMI and then use
drm_hdmi_audio_helper features to provide audio support. Your
implementations misses ELD, plugged callback, etc.

> ---
>  drivers/gpu/drm/bridge/Kconfig           |   1 +
>  drivers/gpu/drm/bridge/lontium-lt8912b.c | 107 ++++++++++++++++++++++-
>  2 files changed, 107 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
> index 6b4664d91faa..489ce1041203 100644
> --- a/drivers/gpu/drm/bridge/Kconfig
> +++ b/drivers/gpu/drm/bridge/Kconfig
> @@ -117,6 +117,7 @@ config DRM_ITE_IT6505
>  
>  config DRM_LONTIUM_LT8912B
>  	tristate "Lontium LT8912B DSI/HDMI bridge"
> +	select SND_SOC_HDMI_CODEC if SND_SOC
>  	depends on OF
>  	select DRM_PANEL_BRIDGE
>  	select DRM_KMS_HELPER
> diff --git a/drivers/gpu/drm/bridge/lontium-lt8912b.c b/drivers/gpu/drm/bridge/lontium-lt8912b.c
> index 52da204f5740..2100b41e5f61 100644
> --- a/drivers/gpu/drm/bridge/lontium-lt8912b.c
> +++ b/drivers/gpu/drm/bridge/lontium-lt8912b.c
> @@ -8,6 +8,8 @@
>  #include <linux/gpio/consumer.h>
>  #include <linux/i2c.h>
>  #include <linux/media-bus-format.h>
> +#include <linux/of_graph.h>
> +#include <linux/platform_device.h>
>  #include <linux/regmap.h>
>  
>  #include <drm/drm_probe_helper.h>
> @@ -16,6 +18,8 @@
>  #include <drm/drm_mipi_dsi.h>
>  #include <drm/drm_of.h>
>  
> +#include <sound/hdmi-codec.h>
> +
>  #include <video/videomode.h>
>  
>  #define I2C_MAIN 0
> @@ -24,7 +28,10 @@
>  #define I2C_CEC_DSI 1
>  #define I2C_ADDR_CEC_DSI 0x49
>  
> -#define I2C_MAX_IDX 2
> +#define I2C_AUDIO 2
> +#define I2C_ADDR_AUDIO 0x4a
> +
> +#define I2C_MAX_IDX 3
>  
>  struct lt8912 {
>  	struct device *dev;
> @@ -38,6 +45,7 @@ struct lt8912 {
>  	struct drm_bridge *hdmi_port;
>  
>  	struct mipi_dsi_device *dsi;
> +	struct platform_device *audio_pdev;
>  
>  	struct gpio_desc *gp_reset;
>  
> @@ -226,6 +234,7 @@ static int lt8912_init_i2c(struct lt8912 *lt, struct i2c_client *client)
>  	struct i2c_board_info info[] = {
>  		{ I2C_BOARD_INFO("lt8912p0", I2C_ADDR_MAIN), },
>  		{ I2C_BOARD_INFO("lt8912p1", I2C_ADDR_CEC_DSI), },
> +		{ I2C_BOARD_INFO("lt8912p2", I2C_ADDR_AUDIO), },
>  	};
>  
>  	if (!lt)
> @@ -754,6 +763,97 @@ static int lt8912_put_dt(struct lt8912 *lt)
>  	return 0;
>  }
>  
> +static int lt8912_hdmi_hw_params(struct device *dev, void *data,
> +				 struct hdmi_codec_daifmt *fmt,
> +				 struct hdmi_codec_params *hparms)
> +{
> +	struct lt8912 *lt = data;
> +	unsigned int audio_params = 0x08; /* 16 bit word size */
> +
> +	if (hparms->sample_width != 16)
> +		return -EINVAL;
> +
> +	if (hparms->sample_rate == 48000)
> +		audio_params |= 0x20;
> +	else if (hparms->sample_rate == 96000)
> +		audio_params |= 0xa0;
> +	else
> +		return -EINVAL;
> +
> +	regmap_write(lt->regmap[I2C_AUDIO], 0x0f, audio_params);
> +	regmap_write(lt->regmap[I2C_AUDIO], 0x35, 0x00);
> +	regmap_write(lt->regmap[I2C_AUDIO], 0x36, 0x18);
> +	regmap_write(lt->regmap[I2C_AUDIO], 0x37, 0x00);
> +
> +	return 0;
> +}
> +
> +static int lt8912_audio_startup(struct device *dev, void *data)
> +{
> +	struct lt8912 *lt = data;
> +
> +	regmap_write(lt->regmap[I2C_AUDIO], 0x34, 0xe2);
> +	regmap_write(lt->regmap[I2C_AUDIO], 0x3c, 0x60);
> +	regmap_write(lt->regmap[I2C_AUDIO], 0x07, 0xf0);
> +	regmap_write(lt->regmap[I2C_AUDIO], 0x06, 0x08);
> +
> +	return 0;
> +}
> +
> +static void lt8912_audio_shutdown(struct device *dev, void *data)
> +{
> +	struct lt8912 *lt = data;
> +
> +	regmap_write(lt->regmap[I2C_AUDIO], 0x06, 0x00);
> +	regmap_write(lt->regmap[I2C_AUDIO], 0x07, 0x00);
> +	regmap_write(lt->regmap[I2C_AUDIO], 0x34, 0x52);
> +	regmap_write(lt->regmap[I2C_AUDIO], 0x3c, 0x40);
> +}
> +
> +static int lt8912_hdmi_i2s_get_dai_id(struct snd_soc_component *component,
> +				      struct device_node *endpoint)
> +{
> +	struct of_endpoint of_ep;
> +	int ret;
> +
> +	ret = of_graph_parse_endpoint(endpoint, &of_ep);
> +	if (ret < 0)
> +		return ret;
> +
> +	if (of_ep.port != 2)
> +		return -EINVAL;
> +
> +	return 0;
> +}
> +
> +static const struct hdmi_codec_ops lt8912_codec_ops = {
> +	.hw_params = lt8912_hdmi_hw_params,
> +	.audio_shutdown = lt8912_audio_shutdown,
> +	.audio_startup = lt8912_audio_startup,
> +	.get_dai_id = lt8912_hdmi_i2s_get_dai_id,
> +};
> +
> +static int lt8912_audio_init(struct device *dev, struct lt8912 *lt)
> +{
> +	struct hdmi_codec_pdata codec_data = {
> +		.ops = &lt8912_codec_ops,
> +		.max_i2s_channels = 2,
> +		.i2s = 1,
> +		.data = lt,
> +	};
> +
> +	lt->audio_pdev = platform_device_register_data(dev, HDMI_CODEC_DRV_NAME,
> +						       PLATFORM_DEVID_AUTO,
> +						       &codec_data, sizeof(codec_data));
> +
> +	return PTR_ERR_OR_ZERO(lt->audio_pdev);
> +}
> +
> +static void lt8912_audio_exit(struct lt8912 *lt)
> +{
> +	platform_device_unregister(lt->audio_pdev);
> +}
> +
>  static int lt8912_probe(struct i2c_client *client)
>  {
>  	static struct lt8912 *lt;
> @@ -788,6 +888,10 @@ static int lt8912_probe(struct i2c_client *client)
>  	if (ret)
>  		goto err_attach;
>  
> +	ret = lt8912_audio_init(dev, lt);
> +	if (ret)
> +		goto err_attach;
> +
>  	return 0;
>  
>  err_attach:
> @@ -803,6 +907,7 @@ static void lt8912_remove(struct i2c_client *client)
>  {
>  	struct lt8912 *lt = i2c_get_clientdata(client);
>  
> +	lt8912_audio_exit(lt);
>  	drm_bridge_remove(&lt->bridge);
>  	lt8912_free_i2c(lt);
>  	lt8912_put_dt(lt);
> -- 
> 2.47.2
> 

-- 
With best wishes
Dmitry