linux-kernel - Re: [PATCH v7 3/9] drm/display: Add Type-C switch helpers

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Message-ID: <Y7bvnOLcuJvvp/v1@smile.fi.intel.com>
Date:   Thu, 5 Jan 2023 17:41:16 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Pin-yen Lin <treapking@...omium.org>
Cc:     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>,
        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>,
        Nícolas F . R . A . Prado 
        <nfraprado@...labora.com>, Xin Ji <xji@...logixsemi.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Hsin-Yi Wang <hsinyi@...omium.org>,
        linux-kernel@...r.kernel.org, Allen Chen <allen.chen@....com.tw>,
        linux-acpi@...r.kernel.org, Lyude Paul <lyude@...hat.com>,
        dri-devel@...ts.freedesktop.org, chrome-platform@...ts.linux.dev,
        Javier Martinez Canillas <javierm@...hat.com>,
        Marek Vasut <marex@...x.de>, devicetree@...r.kernel.org,
        Stephen Boyd <swboyd@...omium.org>,
        Douglas Anderson <dianders@...omium.org>,
        Imre Deak <imre.deak@...el.com>,
        Jani Nikula <jani.nikula@...el.com>,
        Kees Cook <keescook@...omium.org>,
        Khaled Almahallawy <khaled.almahallawy@...el.com>,
        Ville Syrjälä 
        <ville.syrjala@...ux.intel.com>,
        shaomin Deng <dengshaomin@...rlc.com>
Subject: Re: [PATCH v7 3/9] drm/display: Add Type-C switch helpers

On Thu, Jan 05, 2023 at 09:24:51PM +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.

...

> +	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;

...

> +	struct device_node *sw;

> +	int ret = 0;

It's easy to break things if you squeeze more code in the future in this
function, so I recommend to split assignment to be closer to its first user
(see below).

> +	for_each_child_of_node(port, sw) {
> +		if (of_property_read_bool(sw, "mode-switch"))
> +			switch_desc->num_typec_switches++;
> +	}
> +
> +	if (!switch_desc->num_typec_switches) {
> +		dev_warn(dev, "No Type-C switches node found\n");

> +		return ret;

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"))
> +			continue;
> +		ret = drm_dp_register_mode_switch(dev, sw, switch_desc, data, mux_set);
> +		if (ret) {
> +			dev_err(dev, "Failed to register mode switch: %d\n", ret);
> +			of_node_put(sw);
> +			break;
> +		}
> +	}

> +	if (ret)
> +		drm_dp_unregister_typec_switches(switch_desc);
> +
> +	return ret;

Why not adding a goto label?

		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;

-- 
With Best Regards,
Andy Shevchenko