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	Tue, 07 Jan 2025 10:46:29 +0100
Date: Tue, 7 Jan 2025 10:46:29 +0100
From: Johan Hovold <johan@kernel.org>
To: Abel Vesa <abel.vesa@linaro.org>
Cc: Heikki Krogerus <heikki.krogerus@linux.intel.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Rob Herring <robh@kernel.org>,
	Krzysztof Kozlowski <krzk+dt@kernel.org>,
	Conor Dooley <conor+dt@kernel.org>,
	Bjorn Andersson <andersson@kernel.org>,
	Konrad Dybcio <konradybcio@kernel.org>,
	Rajendra Nayak <quic_rjendra@quicinc.com>,
	Sibi Sankar <quic_sibis@quicinc.com>,
	Dmitry Baryshkov <dmitry.baryshkov@linaro.org>,
	Trilok Soni <quic_tsoni@quicinc.com>,
	Christophe JAILLET <christophe.jaillet@wanadoo.fr>,
	linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org,
	linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org
Subject: Re: [PATCH v5 2/6] usb: typec: Add support for Parade PS8830 Type-C
 Retimer
Message-ID: <Z3z39Z_BH1stsO0c@hovoldconsulting.com>
References: <20241112-x1e80100-ps8830-v5-0-4ad83af4d162@linaro.org>
 <20241112-x1e80100-ps8830-v5-2-4ad83af4d162@linaro.org>
 <Z1CCVjEZMQ6hJ-wK@hovoldconsulting.com>
 <Z3vlTwR+SiZQWVh7@linaro.org>
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In-Reply-To: <Z3vlTwR+SiZQWVh7@linaro.org>

On Mon, Jan 06, 2025 at 04:14:39PM +0200, Abel Vesa wrote:
> On 24-12-04 17:24:54, Johan Hovold wrote:
> > On Tue, Nov 12, 2024 at 07:01:11PM +0200, Abel Vesa wrote:

> > > +	/* skip resetting if already configured */
> > > +	if (regmap_test_bits(retimer->regmap, REG_USB_PORT_CONN_STATUS_0,
> > > +			     CONN_STATUS_0_CONNECTION_PRESENT))
> > > +		return 0;
> > 
> > What if the device is held in reset? This looks like it only works if
> > the boot firmware has already enabled the retimer. Otherwise you may
> > return success from probe here with the retimer still in reset.
> 
> Please correct me if I'm wrong, but if the read above fails or reads
> anything else than "connection present", then below we go through the
> resetting sequence. If it reads "connection present", then retimer can't
> be in reset.

regmap_test_bits() returns a negative errno if the read fails, so you
need to check that the return value is 1 here to avoid returning success
from probe on failure.

Johan