linux-kernel - Re: [PATCH] phy dp83867: depend on CONFIG_OF

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Date:	Mon, 16 May 2016 13:22:57 -0500
From:	Dan Murphy <dmurphy@...com>
To:	Alexander Graf <agraf@...e.de>, <netdev@...r.kernel.org>
CC:	<linux-kernel@...r.kernel.org>, <michal.simek@...inx.com>
Subject: Re: [PATCH] phy dp83867: depend on CONFIG_OF_MDIO

Alex

On 05/16/2016 12:57 PM, Alexander Graf wrote:
> Hi Dan,
>
> On 16.05.16 15:38, Dan Murphy wrote:
>> Alexander
>>
>> On 05/16/2016 06:28 AM, Alexander Graf wrote:
>>> The DP83867 phy driver doesn't actually work when CONFIG_OF_MDIO isn't enabled.
>>> It simply passes the device tree test, but leaves all internal configuration
>>> initialized at 0. Then it configures the phy with those values and renders a
>>> previously working configuration useless.
>>>
>>> This patch makes sure that we only build the DP83867 phy code when
>>> CONFIG_OF_MDIO is set, to not run into that problem.
>>>
>>> Signed-off-by: Alexander Graf <agraf@...e.de>
>>> ---
>>>  drivers/net/phy/Kconfig   | 1 +
>>>  drivers/net/phy/dp83867.c | 7 -------
>>>  2 files changed, 1 insertion(+), 7 deletions(-)
>>>
>>> diff --git a/drivers/net/phy/Kconfig b/drivers/net/phy/Kconfig
>>> index 6dad9a9..4265ad5 100644
>>> --- a/drivers/net/phy/Kconfig
>>> +++ b/drivers/net/phy/Kconfig
>>> @@ -148,6 +148,7 @@ config DP83848_PHY
>>>  
>>>  config DP83867_PHY
>>>  	tristate "Drivers for Texas Instruments DP83867 Gigabit PHY"
>>> +	depends on OF_MDIO
>>>  	---help---
>>>  	  Currently supports the DP83867 PHY.
>>>  
>>> diff --git a/drivers/net/phy/dp83867.c b/drivers/net/phy/dp83867.c
>>> index 2afa61b..ff867ba 100644
>>> --- a/drivers/net/phy/dp83867.c
>>> +++ b/drivers/net/phy/dp83867.c
>>> @@ -99,7 +99,6 @@ static int dp83867_config_intr(struct phy_device *phydev)
>>>  	return phy_write(phydev, MII_DP83867_MICR, micr_status);
>>>  }
>>>  
>>> -#ifdef CONFIG_OF_MDIO
>>>  static int dp83867_of_init(struct phy_device *phydev)
>>>  {
>>>  	struct dp83867_private *dp83867 = phydev->priv;
>>> @@ -123,12 +122,6 @@ static int dp83867_of_init(struct phy_device *phydev)
>>>  	return of_property_read_u32(of_node, "ti,fifo-depth",
>>>  				   &dp83867->fifo_depth);
>>>  }
>>> -#else
>>> -static int dp83867_of_init(struct phy_device *phydev)
>>> -{
>>> -	return 0;
>>> -}
>>> -#endif /* CONFIG_OF_MDIO */
>>>  
>>>  static int dp83867_config_init(struct phy_device *phydev)
>>>  {
>> I don't think we want this to depend solely on OF_MDIO.
>>
>> The #else case should probably be coded to look at platform data, if
>> it exists.  I don't have any boards that still used platform data to test this
>> out so I did not feel comfortable adding code I could not test.
> Since there was no code to look at platform data, those boards would be
> broken just as well today, no? So at the end of the day, this change
> should be no regression for them.

As Andrew pointed out if you are not using RGMII you don't need internal delay or fifo_depth so making the driver dependent on OF_MDIO
does not make sense.

The DP83867 RGMII tx and rx delays and fifo should really be changed to optional parameters and only programmed if set.

Dan
>
> Alex


-- 
------------------
Dan Murphy