Introduce a bus-width property to define the number of parallel RGB
input pins connected to the transmitter. The input bus formats are updated
accordingly. If the property is not specified, default to 24-bit bus-width.

Signed-off-by: Wadim Egorov <w.egorov@phytec.de>
---
v2:
  - Use bus-width instead of data-lines as suggested by Krzysztof
  - Handle default case separately as an error case
---
 drivers/gpu/drm/bridge/sii902x.c | 28 +++++++++++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/bridge/sii902x.c b/drivers/gpu/drm/bridge/sii902x.c
index 7f91b0db161e..3b9e4e1dec45 100644
--- a/drivers/gpu/drm/bridge/sii902x.c
+++ b/drivers/gpu/drm/bridge/sii902x.c
@@ -180,6 +180,8 @@ struct sii902x {
 	struct gpio_desc *reset_gpio;
 	struct i2c_mux_core *i2cmux;
 	bool sink_is_hdmi;
+	u32 bus_width;
+
 	/*
 	 * Mutex protects audio and video functions from interfering
 	 * each other, by keeping their i2c command sequences atomic.
@@ -477,6 +479,8 @@ static u32 *sii902x_bridge_atomic_get_input_bus_fmts(struct drm_bridge *bridge,
 						     u32 output_fmt,
 						     unsigned int *num_input_fmts)
 {
+
+	struct sii902x *sii902x = bridge_to_sii902x(bridge);
 	u32 *input_fmts;
 
 	*num_input_fmts = 0;
@@ -485,7 +489,20 @@ static u32 *sii902x_bridge_atomic_get_input_bus_fmts(struct drm_bridge *bridge,
 	if (!input_fmts)
 		return NULL;
 
-	input_fmts[0] = MEDIA_BUS_FMT_RGB888_1X24;
+	switch (sii902x->bus_width) {
+	case 16:
+		input_fmts[0] = MEDIA_BUS_FMT_RGB565_1X16;
+		break;
+	case 18:
+		input_fmts[0] = MEDIA_BUS_FMT_RGB666_1X18;
+		break;
+	case 24:
+		input_fmts[0] = MEDIA_BUS_FMT_RGB888_1X24;
+		break;
+	default:
+		return NULL;
+	}
+
 	*num_input_fmts = 1;
 
 	return input_fmts;
@@ -1167,6 +1184,15 @@ static int sii902x_probe(struct i2c_client *client)
 		return PTR_ERR(sii902x->reset_gpio);
 	}
 
+	endpoint = of_graph_get_endpoint_by_regs(dev->of_node, 0, -1);
+	if (endpoint) {
+		ret = of_property_read_u32(endpoint, "bus-width", &sii902x->bus_width);
+		if (ret) {
+			dev_dbg(dev, "Could not get bus-width, defaulting to 24-bit bus-width\n");
+			sii902x->bus_width = 24;
+		}
+	}
+
 	endpoint = of_graph_get_endpoint_by_regs(dev->of_node, 1, -1);
 	if (endpoint) {
 		struct device_node *remote = of_graph_get_remote_port_parent(endpoint);
-- 
2.34.1

On Mon, Oct 07, 2024 at 10:52:13AM +0200, Wadim Egorov wrote:
> Introduce a bus-width property to define the number of parallel RGB
> input pins connected to the transmitter. The input bus formats are updated
> accordingly. If the property is not specified, default to 24-bit bus-width.
> 
> Signed-off-by: Wadim Egorov <w.egorov@phytec.de>
> ---
> v2:
>   - Use bus-width instead of data-lines as suggested by Krzysztof
>   - Handle default case separately as an error case
> ---
>  drivers/gpu/drm/bridge/sii902x.c | 28 +++++++++++++++++++++++++++-
>  1 file changed, 27 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/bridge/sii902x.c b/drivers/gpu/drm/bridge/sii902x.c
> index 7f91b0db161e..3b9e4e1dec45 100644
> --- a/drivers/gpu/drm/bridge/sii902x.c
> +++ b/drivers/gpu/drm/bridge/sii902x.c
> @@ -180,6 +180,8 @@ struct sii902x {
>  	struct gpio_desc *reset_gpio;
>  	struct i2c_mux_core *i2cmux;
>  	bool sink_is_hdmi;
> +	u32 bus_width;
> +
>  	/*
>  	 * Mutex protects audio and video functions from interfering
>  	 * each other, by keeping their i2c command sequences atomic.
> @@ -477,6 +479,8 @@ static u32 *sii902x_bridge_atomic_get_input_bus_fmts(struct drm_bridge *bridge,
>  						     u32 output_fmt,
>  						     unsigned int *num_input_fmts)
>  {
> +
> +	struct sii902x *sii902x = bridge_to_sii902x(bridge);
>  	u32 *input_fmts;
>  
>  	*num_input_fmts = 0;
> @@ -485,7 +489,20 @@ static u32 *sii902x_bridge_atomic_get_input_bus_fmts(struct drm_bridge *bridge,
>  	if (!input_fmts)
>  		return NULL;
>  
> -	input_fmts[0] = MEDIA_BUS_FMT_RGB888_1X24;
> +	switch (sii902x->bus_width) {
> +	case 16:
> +		input_fmts[0] = MEDIA_BUS_FMT_RGB565_1X16;
> +		break;
> +	case 18:
> +		input_fmts[0] = MEDIA_BUS_FMT_RGB666_1X18;
> +		break;
> +	case 24:
> +		input_fmts[0] = MEDIA_BUS_FMT_RGB888_1X24;
> +		break;
> +	default:
> +		return NULL;
> +	}
> +
>  	*num_input_fmts = 1;
>  
>  	return input_fmts;
> @@ -1167,6 +1184,15 @@ static int sii902x_probe(struct i2c_client *client)
>  		return PTR_ERR(sii902x->reset_gpio);
>  	}
>  
> +	endpoint = of_graph_get_endpoint_by_regs(dev->of_node, 0, -1);

More common pattern would be:

sii902x->bus_width = 24;
/* ignore the error */
if (endpoint)
	of_property_read_u32(endpoint, "bus-width", &sii902x->bus_width);


> +	if (endpoint) {
> +		ret = of_property_read_u32(endpoint, "bus-width", &sii902x->bus_width);
> +		if (ret) {
> +			dev_dbg(dev, "Could not get bus-width, defaulting to 24-bit bus-width\n");
> +			sii902x->bus_width = 24;

If endpoint isn't defined in DT (for whatever reasons), bus_width is also not set in the code.

> +		}
> +	}
> +
>  	endpoint = of_graph_get_endpoint_by_regs(dev->of_node, 1, -1);
>  	if (endpoint) {
>  		struct device_node *remote = of_graph_get_remote_port_parent(endpoint);
> -- 
> 2.34.1
> 

-- 
With best wishes
Dmitry