linux-kernel - Re: [PATCH v4 18/18] platform/chrome: cros_ec

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Message-ID: <ZtgqLZXbJbpG65vD@google.com>
Date: Wed, 4 Sep 2024 09:36:45 +0000
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>,
	Pin-yen Lin <treapking@...omium.org>,
	Andrzej Hajda <andrzej.hajda@...el.com>,
	Benson Leung <bleung@...omium.org>,
	Conor Dooley <conor+dt@...nel.org>, Daniel Vetter <daniel@...ll.ch>,
	David Airlie <airlied@...il.com>,
	Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
	dri-devel@...ts.freedesktop.org,
	Guenter Roeck <groeck@...omium.org>,
	Jernej Skrabec <jernej.skrabec@...il.com>,
	Jonas Karlman <jonas@...boo.se>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
	Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
	Lee Jones <lee@...nel.org>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Neil Armstrong <neil.armstrong@...aro.org>,
	Prashant Malani <pmalani@...omium.org>,
	Robert Foss <rfoss@...nel.org>, Rob Herring <robh+dt@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	Alexandre Belloni <alexandre.belloni@...tlin.com>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
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	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
	Ivan Orlov <ivan.orlov0322@...il.com>, linux-acpi@...r.kernel.org,
	linux-usb@...r.kernel.org,
	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	"Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
	Sakari Ailus <sakari.ailus@...ux.intel.com>,
	Vinod Koul <vkoul@...nel.org>
Subject: Re: [PATCH v4 18/18] platform/chrome: cros_ec_typec: Handle lack of
 HPD information

On Sat, Aug 31, 2024 at 09:06:56PM -0700, Stephen Boyd wrote:
> +static void cros_typec_inject_hpd(struct cros_typec_data *typec,
> +				  struct ec_response_usb_pd_mux_info *resp,
> +				  struct cros_typec_port *port)
> +{
[...]
> +	/*
> +	 * Only read the mux GPIO setting if we need to change the active port.
> +	 * Otherwise, an active port is already set and HPD going high or low
> +	 * doesn't change the muxed port until DP mode is exited.
> +	 */
> +	if (!typec->active_dp_port) {

Given that cros_typec_inject_hpd() is called before `typec->active_dp_port`
would be set (from previous patch "platform/chrome: ...  Support DP muxing"),
would it possibly wrongly fall into here at the beginning?  (E.g.:
cros_typec_probe() -> cros_typec_port_update() -> cros_typec_configure_mux()
-> cros_typec_inject_hpd().)

> [...]
> +	/* Inject HPD from the GPIO state if EC firmware is broken. */
> +	if (typec->hpd_asserted)
> +		resp->flags |= USB_PD_MUX_HPD_LVL;

`typec->hpd_asserted` is shared between all typec->ports[...].  Would it be
possible that a HPD is asserted for another port but not current `port`?
E.g.: cros_typec_inject_hpd() for port 2 and cros_typec_dp_bridge_hpd_notify()
gets called due to port 1 at the same time?