netdev - Re: [PATCH net] usbnet: smsc95xx: Fix deadlock on runtime resume

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Date:   Wed, 27 Apr 2022 17:24:50 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Lukas Wunner <lukas@...ner.de>
Cc:     Steve Glendinning <steve.glendinning@...well.net>,
        UNGLinuxDriver@...rochip.com, Oliver Neukum <oneukum@...e.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org,
        linux-usb@...r.kernel.org, Andre Edich <andre.edich@...rochip.com>,
        Oleksij Rempel <o.rempel@...gutronix.de>,
        Martyn Welch <martyn.welch@...labora.com>,
        Gabriel Hojda <ghojda@...urs.ro>,
        Christoph Fritz <chf.fritz@...glemail.com>,
        Lino Sanfilippo <LinoSanfilippo@....de>,
        Philipp Rosenberger <p.rosenberger@...bus.com>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Russell King <linux@...linux.org.uk>
Subject: Re: [PATCH net] usbnet: smsc95xx: Fix deadlock on runtime resume

On Wed, Apr 27, 2022 at 08:41:49AM +0200, Lukas Wunner wrote:
> Commit 05b35e7eb9a1 ("smsc95xx: add phylib support") amended
> smsc95xx_resume() to call phy_init_hw().  That function waits for the
> device to runtime resume even though it is placed in the runtime resume
> path, causing a deadlock.

Hi Lukas

You have looked at this code, tried a few different things, so this is
probably a dumb question.

Do you actually need to call phy_init_hw()?

mdio_bus_phy_resume() will call phy_init_hw(). So long as you first
resume the MAC and then the PHY, shouldn't this just work?

       Andrew