netdev - Re: [PATCH net 1/1] mdio_bus: fix mdio_register_device when RESET

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Date:   Thu, 21 Nov 2019 03:08:22 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>,
        David Bauer <mail@...id-bauer.net>
Cc:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Marek Behún <marek.behun@....cz>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        David Bauer <mail@...id-bauer.net>,
        "David S. Miller" <davem@...emloft.net>,
        Sergei Shtylyov <sergei.shtylyov@...entembedded.com>,
        netdev@...r.kernel.org, linux-renesas-soc@...r.kernel.org
Subject: Re: [PATCH net 1/1] mdio_bus: fix mdio_register_device when
 RESET_CONTROLLER is disabled

> The difference with the non-optional case is that
> __devm_reset_control_get() registers a cleanup function if there's
> no error condition, even for NULL (which is futile, will send a patch).
> 
> However, more importantly, mdiobus_register_reset() calls a devm_*()
> function on "&mdiodev->dev" ("mdio_bus ee700000.ethernet-ffffffff:01"),
> which is a different device than the one being probed
> (("ee700000.ethernet"), see also the callstack below).
> In fact "&mdiodev->dev" hasn't been probed yet, leading to the WARNING
> when it is probed later.
> 
>     [<c0582de8>] (mdiobus_register_device) from [<c05810e0>] (phy_device_register+0xc/0x74)
>     [<c05810e0>] (phy_device_register) from [<c0675ef4>] (of_mdiobus_register_phy+0x144/0x17c)
>     [<c0675ef4>] (of_mdiobus_register_phy) from [<c06760f0>] (of_mdiobus_register+0x1c4/0x2d0)
>     [<c06760f0>] (of_mdiobus_register) from [<c0589f0c>] (sh_eth_drv_probe+0x778/0x8ac)
>     [<c0589f0c>] (sh_eth_drv_probe) from [<c0516ce8>] (platform_drv_probe+0x48/0x94)
> 
> Has commit 71dd6c0dff51b5f1 ("net: phy: add support for
> reset-controller") been tested with an actual reset present?
> 
> Are Ethernet drivers not (no longer) allowed to register MDIO busses?

That is not good. The devm_reset_control_get() call need replaces with
an unmanaged version, and a call to reset_control_put() added to
mdiobus_unregister_device().

David, could you look at this, it was a patch from you that added
this.

	Andrew