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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>,
        Conor Dooley <conor.dooley@microchip.com>
Subject: Re: [PATCH v2 0/7] usb: cdns: fix suspend on J7200 by assuming
 reset-on-resume
In-Reply-To: <20231120-j7200-usb-suspend-v2-0-038c7e4a3df4@bootlin.com>
References: <20231120-j7200-usb-suspend-v2-0-038c7e4a3df4@bootlin.com>
Date:   Wed, 22 Nov 2023 15:44:22 -0800
Message-ID: <7ho7fle4kp.fsf@baylibre.com>
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Théo Lebrun <theo.lebrun@bootlin.com> writes:

> Hi,
>
> Suspend on the TI J7200 platform is broken currently. There are two
> components that need to be patched so that they assume reset on
> resume: (1) the TI wrapper cdns3-ti & (2) the HOST role of the
> controller.
>
> About (1): the TI wrapper only did its hardware configuration at probe
> time. Update so that it is done at resume on J7200 SoC.
>
> About (2): signal from cdns3-ti to cdns3 host to xHCI that the
> controller resets on resume. This way we avoid the following warning:
>
>    xhci-hcd xhci-hcd.1.auto: xHC error in resume, USBSTS 0x401, Reinit
>
> Strictly speaking (2) is not required to have working suspend on J7200;
> its only goal is to silence this warning.
>
> Those patches have been tested on the TI J7200 EVM GP. No need to
> mention that other patches are required for S2R to work, but those will
> be sent later down the road. Those USB patches are rather standalone.
>
> Thanks,
> Théo
>
> --
> Théo Lebrun, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com
>
> Signed-off-by: Théo Lebrun <theo.lebrun@bootlin.com>
> ---
> Changes in v2:
> - Remove runtime PM from cdns3-ti; it brings nothing. That means our
>   cdns3-ti suspend/resume patch is simpler; there is no need to handle
>   runtime PM at suspend/resume.

Sorry I sent comments on v2 before I noticed v3 was out, but this is not
a good idea IMO.  I sent more detailed comment on that specific patch.

Kevin