netdev - Re: net: phy: question about phy_is

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Date:   Fri, 09 Feb 2018 14:31:57 +0900
From:   Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     netdev@...r.kernel.org
Subject: Re: net: phy: question about phy_is_internal for generic-phy

Hi Andrew,

On Thu, 8 Feb 2018 13:51:44 +0100 <andrew@...n.ch> wrote:

> On Thu, Feb 08, 2018 at 07:09:25PM +0900, Kunihiko Hayashi wrote:
> > Hello,
> > 
> > Is there a way to specify "phy is internal" to generic phy driver,
> > that is, to make phy_is_internal() function available?
> > 
> > I found "phy-is-integrated" DT property in
> > Documentation/devicetree/bindings/net/phy.txt, however, it seems
> > that the property is no effect for generic phy. And I think that
> > the meaning of "integrated" is slightly different from "internal".
> 
> Hi Kunihiko
> 
> Could you explain the bigger picture. Why do you need this?

There are some SoCs that have a built-in phy, and sometimes
these SoCs can choose to use built-in phy or external phy.

In our case, MAC driver needs to set a register to choose whether
to use them. This choice depends on the board implemented on the SoC.
And this built-in phy can be driven with generic phy driver.

If 'struct phy_driver' of a phy driver has the flag with
PHY_IS_INTERNAL, phy_is_internal() returns true,
and the MAC driver can decide a value of the register using it.

drivers/net/phy/phy_device.c:

	if (phydrv->flags & PHY_IS_INTERNAL)
        	phydev->is_internal = true;

include/linux/phy.h:

	static inline bool phy_is_internal(struct phy_device *phydev)
	{
	        return phydev->is_internal;
	}

Although I can write a new driver with PHY_IS_INTERNAL, or
add a new property to the MAC driver,
I'd like to use generic phy driver if possible.

However, it seems that the generic phy driver doesn't have the way
to express built-in phy with/without even DT.

How can I handle such built-in phy?

Thank you,

---
Best Regards,
Kunihiko Hayashi