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Date: Wed, 4 Sep 2024 09:36:45 +0000
From: Tzung-Bi Shih <tzungbi@kernel.org>
To: Stephen Boyd <swboyd@chromium.org>
Cc: chrome-platform@lists.linux.dev, linux-kernel@vger.kernel.org,
	patches@lists.linux.dev, devicetree@vger.kernel.org,
	Douglas Anderson <dianders@chromium.org>,
	Pin-yen Lin <treapking@chromium.org>,
	Andrzej Hajda <andrzej.hajda@intel.com>,
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	Conor Dooley <conor+dt@kernel.org>, Daniel Vetter <daniel@ffwll.ch>,
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	linux-usb@vger.kernel.org,
	Mika Westerberg <mika.westerberg@linux.intel.com>,
	"Rafael J . Wysocki" <rafael.j.wysocki@intel.com>,
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	Vinod Koul <vkoul@kernel.org>
Subject: Re: [PATCH v4 18/18] platform/chrome: cros_ec_typec: Handle lack of
 HPD information
Message-ID: <ZtgqLZXbJbpG65vD@google.com>
References: <20240901040658.157425-1-swboyd@chromium.org>
 <20240901040658.157425-19-swboyd@chromium.org>
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In-Reply-To: <20240901040658.157425-19-swboyd@chromium.org>

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?