linux-kernel - Re: [PATCH v6 5/7] drm/bridge: anx7625: Register Type C mode switches

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Message-ID: <Y39g/OBLW3pt9qdy@smile.fi.intel.com>
Date:   Thu, 24 Nov 2022 14:18:04 +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>,
        Javier Martinez Canillas <javierm@...hat.com>,
        Stephen Boyd <swboyd@...omium.org>,
        dri-devel@...ts.freedesktop.org,
        Hsin-Yi Wang <hsinyi@...omium.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        devicetree@...r.kernel.org, chrome-platform@...ts.linux.dev,
        linux-acpi@...r.kernel.org, Marek Vasut <marex@...x.de>,
        Xin Ji <xji@...logixsemi.com>, Lyude Paul <lyude@...hat.com>,
        Nícolas F . R . A . Prado 
        <nfraprado@...labora.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        linux-kernel@...r.kernel.org, Allen Chen <allen.chen@....com.tw>
Subject: Re: [PATCH v6 5/7] drm/bridge: anx7625: Register Type C mode switches

On Thu, Nov 24, 2022 at 06:20:54PM +0800, Pin-yen Lin wrote:
> Register USB Type-C mode switches when the "mode-switch" property and
> relevant port are available in Device Tree. Configure the crosspoint
> switch based on the entered alternate mode for a specific Type-C
> connector.

...

> +static void anx7625_typec_two_ports_update(struct anx7625_data *ctx)
> +{
> +	if (ctx->typec_ports[0].dp_connected && ctx->typec_ports[1].dp_connected)
> +		/* Both ports available, do nothing to retain the current one. */
> +		return;

> +	else if (ctx->typec_ports[0].dp_connected)

This 'else' is redundant. I would rewrite above as

	/* Check if both ports available and do nothing to retain the current one */
	if (ctx->typec_ports[0].dp_connected && ctx->typec_ports[1].dp_connected)
		return;

	if (ctx->typec_ports[0].dp_connected)

> +		anx7625_set_crosspoint_switch(ctx, TYPEC_ORIENTATION_NORMAL);
> +	else if (ctx->typec_ports[1].dp_connected)
> +		anx7625_set_crosspoint_switch(ctx, TYPEC_ORIENTATION_REVERSE);
> +}

...

> +	data->dp_connected = (state->alt && state->alt->svid == USB_TYPEC_DP_SID &&
> +			      state->alt->mode == USB_TYPEC_DP_MODE);

Parentheses are not needed.

...

> +	/*
> +	 * <0 1> refers to SSRX1/SSTX1, and <2 3> refers to SSRX2/SSTX2.
> +	 */
> +	for (i = 0; i < num_lanes; i++) {

> +		if (port_num != -1 && port_num != dp_lanes[i] / 2) {
> +			dev_err(dev, "Invalid data lane numbers\n");
> +			return -EINVAL;
> +		}

According to Rob Linux must not validate device tree. If you need it, use
proper YAML schema.

> +		port_num = dp_lanes[i] / 2;
> +	}

...

> +	if (!ctx->num_typec_switches) {
> +		dev_warn(dev, "No Type-C switches node found\n");

> +		return ret;

Why not to return 0 explicitly?

> +	}

...

> +	ctx->typec_ports = devm_kcalloc(

Broken indentation.

> +		dev, ctx->num_typec_switches, sizeof(struct anx7625_port_data),
> +		GFP_KERNEL);
> +	if (!ctx->typec_ports)
> +		return -ENOMEM;

...

> +struct anx7625_port_data {

> +	bool dp_connected;

You can save some bytes on some architectures if move this to be last field.

> +	struct typec_mux_dev *typec_mux;
> +	struct anx7625_data *ctx;
> +};

-- 
With Best Regards,
Andy Shevchenko