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From:   Kevin Hilman <khilman@kernel.org>
To:     =?utf-8?Q?Th=C3=A9o?= Lebrun <theo.lebrun@bootlin.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Conor Dooley <conor+dt@kernel.org>,
        Roger Quadros <rogerq@kernel.org>,
        Peter Chen <peter.chen@kernel.org>,
        Pawel Laszczak <pawell@cadence.com>,
        Nishanth Menon <nm@ti.com>,
        Vignesh Raghavendra <vigneshr@ti.com>,
        Tero Kristo <kristo@kernel.org>
Cc:     linux-usb@vger.kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
        =?utf-8?Q?Gr=C3=A9gory?= Clement <gregory.clement@bootlin.com>,
        =?utf-8?Q?Th=C3=A9o?= Lebrun <theo.lebrun@bootlin.com>
Subject: Re: [PATCH v2 2/7] usb: cdns3-ti: remove runtime PM
In-Reply-To: <20231120-j7200-usb-suspend-v2-2-038c7e4a3df4@bootlin.com>
References: <20231120-j7200-usb-suspend-v2-0-038c7e4a3df4@bootlin.com>
 <20231120-j7200-usb-suspend-v2-2-038c7e4a3df4@bootlin.com>
Date:   Wed, 22 Nov 2023 15:42:56 -0800
Message-ID: <7hsf4xe4n3.fsf@baylibre.com>
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Théo Lebrun <theo.lebrun@bootlin.com> writes:

> The driver does not use RPM. It enables it & gets a reference at probe.
> It then undoes that on probe error or at remove.

...which is a fairly standard thing to do for a rudimentary runtime PM
support on platforms that use power domains.

This will likely (almost surely) break other platforms.

Without a runtime PM get call, the power domain that this device is in
could be powered off without this driver ever knowing about it, causing
a crash as soon as the driver is used after the domain is turned off.

Kevin