Re: [PATCH v10 3/9] drm/display: Add Type-C switch helpers

[Heikki Krogerus]

Hi,

On Thu, Jan 12, 2023 at 12:20:58PM +0800, Pin-yen Lin wrote:
> Add helpers to register and unregister Type-C "switches" for bridges
> capable of switching their output between two downstream devices.
> 
> The helper registers USB Type-C mode switches when the "mode-switch"
> and the "data-lanes" properties are available in Device Tree.

Let's not make this kind of helpers DT only, please. See below ...

> Signed-off-by: Pin-yen Lin <treapking@xxxxxxxxxxxx>
> Tested-by: Chen-Yu Tsai <wenst@xxxxxxxxxxxx>
> Reviewed-by: Chen-Yu Tsai <wenst@xxxxxxxxxxxx>
> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>
> 
> ---
> 
> Changes in v10:
> - Collected Reviewed-by and Tested-by tags
> - Replaced "void *" with "typec_mux_set_fn_t" for mux_set callbacks
> - Print out the node name when errors on parsing DT
> - Use dev_dbg instead of dev_warn when no Type-C switch nodes available
> - Made the return path of drm_dp_register_mode_switch clearer
> 
> Changes in v8:
> - Fixed the build issue when CONFIG_TYPEC=m
> - Fixed some style issues
> 
> Changes in v7:
> - Extracted the common codes to a helper function
> - New in v7
> 
>  drivers/gpu/drm/display/drm_dp_helper.c | 134 ++++++++++++++++++++++++
>  include/drm/display/drm_dp_helper.h     |  17 +++
>  2 files changed, 151 insertions(+)
> 
> diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c
> index 16565a0a5da6..a2ec40a621cb 100644
> --- a/drivers/gpu/drm/display/drm_dp_helper.c
> +++ b/drivers/gpu/drm/display/drm_dp_helper.c
> @@ -30,11 +30,13 @@
>  #include <linux/sched.h>
>  #include <linux/seq_file.h>
>  #include <linux/string_helpers.h>
> +#include <linux/usb/typec_mux.h>
>  #include <linux/dynamic_debug.h>
>  
>  #include <drm/display/drm_dp_helper.h>
>  #include <drm/display/drm_dp_mst_helper.h>
>  #include <drm/drm_edid.h>
> +#include <drm/drm_of.h>
>  #include <drm/drm_print.h>
>  #include <drm/drm_vblank.h>
>  #include <drm/drm_panel.h>
> @@ -3891,3 +3893,135 @@ int drm_panel_dp_aux_backlight(struct drm_panel *panel, struct drm_dp_aux *aux)
>  EXPORT_SYMBOL(drm_panel_dp_aux_backlight);
>  
>  #endif
> +
> +#if IS_REACHABLE(CONFIG_TYPEC)

I think Jani already pointed out that that is wrong. Just move these
into a separate file and enable them silently in the Makefile when
TYPEC is enabled - so no separate Kconfig option.

> +static int drm_dp_register_mode_switch(struct device *dev, struct device_node *node,

static int drm_dp_register_mode_switch(struct device *dev, struct fwnode_handle *fwnode,

> +				       struct drm_dp_typec_switch_desc *switch_desc,
> +				       void *data, typec_mux_set_fn_t mux_set)
> +{
> +	struct drm_dp_typec_port_data *port_data;
> +	struct typec_mux_desc mux_desc = {};
> +	char name[32];
> +	u32 dp_lanes[2];
> +	int ret, num_lanes, port_num = -1;
> +
> +	num_lanes = drm_of_get_data_lanes_count(node, 0, 2);
> +	if (num_lanes <= 0) {

        num_lanes = fwnode_property_read_u32_array(fwnode, "data-lanes", NULL, 0);
        if (num_lanes <= 0 || num_lanes > 2)

> +		dev_err(dev, "Error on getting data lanes count from %s: %d\n",
> +			node->name, num_lanes);
> +		return num_lanes;
> +	}
> +
> +	ret = of_property_read_u32_array(node, "data-lanes", dp_lanes, num_lanes);

        ret = fwnode_property_read_u32_array(fwnode, "data-lanes", dp_lanes, num_lanes);

> +	if (ret) {
> +		dev_err(dev, "Failed to read the data-lanes variable from %s: %d\n",
> +			node->name, ret);

			fwnode_get_name(fwnode), ret);

> +		return ret;
> +	}
> +
> +	port_num = dp_lanes[0] / 2;
> +
> +	port_data = &switch_desc->typec_ports[port_num];
> +	port_data->data = data;
> +	mux_desc.fwnode = &node->fwnode;

        mux_desc.fwnode = fwnode;

> +	mux_desc.drvdata = port_data;
> +	snprintf(name, sizeof(name), "%s-%u", node->name, port_num);

	snprintf(name, sizeof(name), "%s-%u", fwnode_get_name(fwnode), port_num);

> +	mux_desc.name = name;
> +	mux_desc.set = mux_set;
> +
> +	port_data->typec_mux = typec_mux_register(dev, &mux_desc);
> +	if (IS_ERR(port_data->typec_mux)) {
> +		ret = PTR_ERR(port_data->typec_mux);
> +		dev_err(dev, "Mode switch register for port %d failed: %d\n",
> +			port_num, ret);
> +
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +/**
> + * drm_dp_register_typec_switches() - register Type-C switches
> + * @dev: Device that registers Type-C switches
> + * @port: Device node for the switch
> + * @switch_desc: A Type-C switch descriptor
> + * @data: Private data for the switches
> + * @mux_set: Callback function for typec_mux_set
> + *
> + * This function registers USB Type-C switches for DP bridges that can switch
> + * the output signal between their output pins.
> + *
> + * Currently only mode switches are implemented, and the function assumes the
> + * given @port device node has endpoints with "mode-switch" property.
> + * Register the endpoint as port 0 if the "data-lanes" property falls in 0/1,
> + * and register it as port 1 if "data-lanes" falls in 2/3.
> + */
> +int drm_dp_register_typec_switches(struct device *dev, struct device_node *port,

int drm_dp_register_typec_switches(struct device *dev, struct fwnode_handle *port,

> +				   struct drm_dp_typec_switch_desc *switch_desc,
> +				   void *data, typec_mux_set_fn_t mux_set)
> +{
> +	struct device_node *sw;

        struct fwnode_handle *sw;

> +	int ret;
> +
> +	for_each_child_of_node(port, sw) {
> +		if (of_property_read_bool(sw, "mode-switch"))
> +			switch_desc->num_typec_switches++;
> +	}

        fwnode_for_each_child_node(port, sw)
                if (fwnode_property_present(sw, "mode-switch"))
			switch_desc->num_typec_switches++;

> +	if (!switch_desc->num_typec_switches) {
> +		dev_dbg(dev, "No Type-C switches node found\n");
> +		return 0;
> +	}
> +
> +	switch_desc->typec_ports = devm_kcalloc(
> +		dev, switch_desc->num_typec_switches,
> +		sizeof(struct drm_dp_typec_port_data), GFP_KERNEL);
> +
> +	if (!switch_desc->typec_ports)
> +		return -ENOMEM;
> +
> +	/* Register switches for each connector. */
> +	for_each_child_of_node(port, sw) {
> +		if (!of_property_read_bool(sw, "mode-switch"))

        fwnode_for_each_child_node(port, sw) {
                if (!fwnode_property_present(sw, "mode-switch"))

> +			continue;
> +		ret = drm_dp_register_mode_switch(dev, sw, switch_desc, data, mux_set);
> +		if (ret)
> +			goto err_unregister_typec_switches;
> +	}
> +
> +	return 0;
> +
> +err_unregister_typec_switches:
> +	of_node_put(sw);
> +	drm_dp_unregister_typec_switches(switch_desc);
> +	dev_err(dev, "Failed to register mode switch: %d\n", ret);
> +	return ret;
> +}
> +EXPORT_SYMBOL(drm_dp_register_typec_switches);
> +
> +/**
> + * drm_dp_unregister_typec_switches() - unregister Type-C switches
> + * @switch_desc: A Type-C switch descriptor
> + */
> +void drm_dp_unregister_typec_switches(struct drm_dp_typec_switch_desc *switch_desc)
> +{
> +	int i;
> +
> +	for (i = 0; i < switch_desc->num_typec_switches; i++)
> +		typec_mux_unregister(switch_desc->typec_ports[i].typec_mux);
> +}
> +EXPORT_SYMBOL(drm_dp_unregister_typec_switches);
> +#else
> +void drm_dp_unregister_typec_switches(struct drm_dp_typec_switch_desc *switch_desc)
> +{
> +}
> +EXPORT_SYMBOL(drm_dp_register_typec_switches);
> +int drm_dp_register_typec_switches(struct device *dev, struct device_node *port,
> +				   struct drm_dp_typec_switch_desc *switch_desc,
> +				   void *data, typec_mux_set_fn_t mux_set)
> +{
> +	return 0;
> +}
> +EXPORT_SYMBOL(drm_dp_unregister_typec_switches);
> +#endif
> diff --git a/include/drm/display/drm_dp_helper.h b/include/drm/display/drm_dp_helper.h
> index ab55453f2d2c..5a3824f13b4e 100644
> --- a/include/drm/display/drm_dp_helper.h
> +++ b/include/drm/display/drm_dp_helper.h
> @@ -25,6 +25,7 @@
>  
>  #include <linux/delay.h>
>  #include <linux/i2c.h>
> +#include <linux/usb/typec_mux.h>
>  
>  #include <drm/display/drm_dp.h>
>  #include <drm/drm_connector.h>
> @@ -763,4 +764,20 @@ bool drm_dp_downstream_rgb_to_ycbcr_conversion(const u8 dpcd[DP_RECEIVER_CAP_SIZ
>  					       const u8 port_cap[4], u8 color_spc);
>  int drm_dp_pcon_convert_rgb_to_ycbcr(struct drm_dp_aux *aux, u8 color_spc);
>  
> +struct drm_dp_typec_port_data {
> +	struct typec_mux_dev *typec_mux;
> +	void *data;
> +	bool dp_connected;
> +};
> +
> +struct drm_dp_typec_switch_desc {
> +	int num_typec_switches;
> +	struct drm_dp_typec_port_data *typec_ports;
> +};
> +
> +void drm_dp_unregister_typec_switches(struct drm_dp_typec_switch_desc *switch_desc);
> +int drm_dp_register_typec_switches(struct device *dev, struct device_node *port,
> +				   struct drm_dp_typec_switch_desc *switch_desc,
> +				   void *data, typec_mux_set_fn_t mux_set);
> +
>  #endif /* _DRM_DP_HELPER_H_ */

The function stubs go here if they are needed.


thanks,

-- 
heikki