linux-kernel - Re: [PATCH v9 3/9] drm/display: Add Type-C switch helpers

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Message-ID: <023519eb-0adb-3b08-71b9-afb92a6cceaf@collabora.com>
Date:   Mon, 9 Jan 2023 12:41:58 +0100
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     Pin-yen Lin <treapking@...omium.org>,
        Andrzej Hajda <andrzej.hajda@...el.com>,
        Neil Armstrong <neil.armstrong@...aro.org>,
        Robert Foss <robert.foss@...aro.org>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Jonas Karlman <jonas@...boo.se>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Daniel Scally <djrscally@...il.com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        Prashant Malani <pmalani@...omium.org>,
        Benson Leung <bleung@...omium.org>,
        Guenter Roeck <groeck@...omium.org>
Cc:     Hsin-Yi Wang <hsinyi@...omium.org>,
        dri-devel@...ts.freedesktop.org, Marek Vasut <marex@...x.de>,
        Stephen Boyd <swboyd@...omium.org>,
        Xin Ji <xji@...logixsemi.com>, linux-acpi@...r.kernel.org,
        devicetree@...r.kernel.org, chrome-platform@...ts.linux.dev,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Allen Chen <allen.chen@....com.tw>,
        Javier Martinez Canillas <javierm@...hat.com>,
        Lyude Paul <lyude@...hat.com>,
        Nícolas F . R . A . Prado 
        <nfraprado@...labora.com>, linux-kernel@...r.kernel.org,
        Douglas Anderson <dianders@...omium.org>,
        Imre Deak <imre.deak@...el.com>,
        Jani Nikula <jani.nikula@...el.com>,
        Jim Cromie <jim.cromie@...il.com>,
        Kees Cook <keescook@...omium.org>,
        Ville Syrjälä <ville.syrjala@...ux.intel.com>
Subject: Re: [PATCH v9 3/9] drm/display: Add Type-C switch helpers

Il 09/01/23 09:40, Pin-yen Lin ha scritto:
> 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.
> 
> Signed-off-by: Pin-yen Lin <treapking@...omium.org>
> 
> ---
> 
> (no changes since v8)
> 
> 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 | 132 ++++++++++++++++++++++++
>   include/drm/display/drm_dp_helper.h     |  16 +++
>   2 files changed, 148 insertions(+)
> 
> diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c
> index 16565a0a5da6..fb9e23744c08 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 +3893,133 @@ 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)
> +static int drm_dp_register_mode_switch(struct device *dev, struct device_node *node,
> +				       struct drm_dp_typec_switch_desc *switch_desc,
> +				       void *data, void *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) {
> +		dev_err(dev, "Error on getting data lanes count: %d\n",
> +			num_lanes);
> +		return num_lanes;
> +	}
> +
> +	ret = of_property_read_u32_array(node, "data-lanes", dp_lanes, num_lanes);
> +	if (ret) {
> +		dev_err(dev, "Failed to read the data-lanes variable: %d\n",
> +			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.drvdata = port_data;
> +	snprintf(name, sizeof(name), "%s-%u", node->name, 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)) {

I would propose, instead...

> +		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 ret;

	return 0;

> +}
> +

...but I don't have strong opinions, so regardless of that:

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>