linux-kernel - Re: [PATCH v3 16/17] platform/chrome: cros_ec

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Message-ID: <ZsdNEWX-eeLiokZl@tzungbi-laptop>
Date: Thu, 22 Aug 2024 22:37:05 +0800
From: Tzung-Bi Shih <tzungbi@...nel.org>
To: Stephen Boyd <swboyd@...omium.org>
Cc: chrome-platform@...ts.linux.dev, linux-kernel@...r.kernel.org,
	patches@...ts.linux.dev, devicetree@...r.kernel.org,
	Douglas Anderson <dianders@...omium.org>,
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	Vinod Koul <vkoul@...nel.org>
Subject: Re: [PATCH v3 16/17] platform/chrome: cros_ec_typec: Support DP
 muxing

On Mon, Aug 19, 2024 at 03:38:30PM -0700, Stephen Boyd wrote:
> @@ -671,6 +674,20 @@ static int cros_typec_configure_mux(struct cros_typec_data *typec, int port_num,
>  	if (port->mux_flags == resp.flags && port->role == pd_ctrl->role)
>  		return 0;
>  
> +	dp_enabled = resp.flags & USB_PD_MUX_DP_ENABLED;
> +	hpd_asserted = resp.flags & USB_PD_MUX_HPD_LVL;
> +	/*
> +	 * Assume the first port to have HPD asserted is the one muxed to DP
> +	 * (i.e. active_port). When there's only one port this delays setting
> +	 * the active_port until HPD is asserted, but before that the
> +	 * drm_connector looks disconnected so active_port doesn't need to be
> +	 * set.
> +	 */
> +	if (dp_bridge && hpd_asserted && !dp_bridge->active_port)
> +		dp_bridge->active_port = port;
> +
> +	is_active_port = !dp_bridge || dp_bridge->active_port == port;

Why `!dp_bridge`?  When will `dp_bridge` be NULL?