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Date:   Thu, 14 Jan 2021 08:54:54 +0800
From:   Peter Chen <hzpeterchen@gmail.com>
To:     Stephan Gerhold <stephan@gerhold.net>
Cc:     "Rafael J. Wysocki" <rafael@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Peter Chen <Peter.Chen@nxp.com>,
        Kishon Vijay Abraham I <kishon@ti.com>,
        "open list:ULTRA-WIDEBAND (UWB) SUBSYSTEM:" 
        <linux-usb@vger.kernel.org>, Thierry Reding <treding@nvidia.com>
Subject: Re: Infinite recursion in device_reorder_to_tail() due to circular
 device links
Message-ID: <20210114005454.GA14220@b29397-desktop>
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On 21-01-13 12:18:35, Stephan Gerhold wrote:
> 
> Also, on a completely different note I looked again at the chipidea USB
> driver that produces this situation. To request the PHY (which ends up
> in the circular device link) it does:
> 
> 	/* Look for a generic PHY first */
> 	ci->phy = devm_phy_get(dev->parent, "usb-phy");
> 
> To me it doesn't really seem great to use the devm_* helpers on the
> parent device either, so I will check if I can refactor this somehow.
> Perhaps this situation can be prevented entirely.
> 

Hi Stephan,

You could try to get the PHY at parent driver
(drivers/usb/chipidea/ci_hdrc_msm.c) to see the difference.

-- 

Thanks,
Peter Chen