linux-kernel - Re: [net-next PATCH v7 04/16] of: mdio: Refactor of_phy_find

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Message-ID: <20210316191719.d7nxgywwhczo7tyg@holly.lan>
Date:   Tue, 16 Mar 2021 19:17:19 +0000
From:   Daniel Thompson <daniel.thompson@...aro.org>
To:     Calvin Johnson <calvin.johnson@....nxp.com>
Cc:     Grant Likely <grant.likely@....com>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        Jeremy Linton <jeremy.linton@....com>,
        Andrew Lunn <andrew@...n.ch>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Russell King - ARM Linux admin <linux@...linux.org.uk>,
        Cristi Sovaiala <cristian.sovaiala@....com>,
        Florin Laurentiu Chiculita <florinlaurentiu.chiculita@....com>,
        Ioana Ciornei <ioana.ciornei@....com>,
        Madalin Bucur <madalin.bucur@....nxp.com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Marcin Wojtas <mw@...ihalf.com>,
        Pieter Jansen Van Vuuren <pieter.jansenvv@...boosystems.io>,
        Jon <jon@...id-run.com>, Saravana Kannan <saravanak@...gle.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        linux-arm-kernel@...ts.infradead.org,
        Diana Madalina Craciun <diana.craciun@....com>,
        linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux.cj@...il.com, netdev@...r.kernel.org,
        Laurentiu Tudor <laurentiu.tudor@....com>,
        "David S. Miller" <davem@...emloft.net>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Jakub Kicinski <kuba@...nel.org>
Subject: Re: [net-next PATCH v7 04/16] of: mdio: Refactor of_phy_find_device()

On Thu, Mar 11, 2021 at 11:49:59AM +0530, Calvin Johnson wrote:
> Refactor of_phy_find_device() to use fwnode_phy_find_device().
> 
> Signed-off-by: Calvin Johnson <calvin.johnson@....nxp.com>

This patch series is provoking depmod dependency cycles for me and
it bisected down to this patch (although I think later patches in
the series add further cycles).

The problems emerge when running modules_install either directly or
indirectly via packaging rules such as bindeb-pkg.

~~~
make -j16 INSTALL_MOD_PATH=$PWD/modules modules_install
...
  INSTALL sound/usb/misc/snd-ua101.ko
  INSTALL sound/usb/snd-usb-audio.ko
  INSTALL sound/usb/snd-usbmidi-lib.ko
  INSTALL sound/xen/snd_xen_front.ko
  DEPMOD  5.12.0-rc3-00009-g1fda33bf463d
depmod: ERROR: Cycle detected: fwnode_mdio -> of_mdio -> fwnode_mdio
depmod: ERROR: Found 2 modules in dependency cycles!
~~~

Kconfig can be found here:
https://gist.github.com/daniel-thompson/6a7d224f3d3950ffa3f63f979b636474

This Kconfig file is for a highly modular kernel derived from the Debian
5.10 arm64 kernel config. I was not able to reproduce using the defconfig
kernel for arm64.


Daniel.


> ---
> 
> Changes in v7: None
> Changes in v6: None
> Changes in v5: None
> Changes in v4: None
> Changes in v3: None
> Changes in v2: None
> 
>  drivers/net/mdio/of_mdio.c | 13 +------------
>  1 file changed, 1 insertion(+), 12 deletions(-)
> 
> diff --git a/drivers/net/mdio/of_mdio.c b/drivers/net/mdio/of_mdio.c
> index d5e0970b2561..b5e0b5b22f1a 100644
> --- a/drivers/net/mdio/of_mdio.c
> +++ b/drivers/net/mdio/of_mdio.c
> @@ -360,18 +360,7 @@ EXPORT_SYMBOL(of_mdio_find_device);
>   */
>  struct phy_device *of_phy_find_device(struct device_node *phy_np)
>  {
> -	struct mdio_device *mdiodev;
> -
> -	mdiodev = of_mdio_find_device(phy_np);
> -	if (!mdiodev)
> -		return NULL;
> -
> -	if (mdiodev->flags & MDIO_DEVICE_FLAG_PHY)
> -		return to_phy_device(&mdiodev->dev);
> -
> -	put_device(&mdiodev->dev);
> -
> -	return NULL;
> +	return fwnode_phy_find_device(of_fwnode_handle(phy_np));
>  }
>  EXPORT_SYMBOL(of_phy_find_device);
>