linux-kernel - Re: [PATCH RESEND net] net: phy: xgmiitorgmii: Support generic PHY status read

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Date:   Fri, 15 Feb 2019 10:53:26 -0800
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Paul Kocialkowski <paul.kocialkowski@...tlin.com>,
        netdev@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Cc:     Andrew Lunn <andrew@...n.ch>,
        Heiner Kallweit <hkallweit1@...il.com>,
        "David S . Miller" <davem@...emloft.net>,
        Michal Simek <michal.simek@...inx.com>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCH RESEND net] net: phy: xgmiitorgmii: Support generic PHY
 status read

On 2/15/19 10:34 AM, Paul Kocialkowski wrote:
> Hi,
> 
> On Fri, 2019-02-15 at 09:38 -0800, Florian Fainelli wrote:
>> On 2/15/19 8:32 AM, Paul Kocialkowski wrote:
>>> Some PHY drivers like the generic one do not provide a read_status
>>> callback on their own but rely on genphy_read_status being called
>>> directly.
>>>
>>> With the current code, this results in a NULL function pointer call.
>>> Call genphy_read_status instead when there is no specific callback.
>>>
>>> Fixes: f411a6160bd4 ("net: phy: Add gmiitorgmii converter support")
>>> Signed-off-by: Paul Kocialkowski <paul.kocialkowski@...tlin.com>
>>> ---
>>> Added Fixes tag and net label for resend.
>>
>> You would want to use phy_read_status() which encapsulates that check as
>> well as checks that the phy_drv pointer is not NULL.
> 
> Well, this driver is a bit different and our priv->phy_drv != phydev-
>> drv, so we can't use the helper directly. I should probably have
> mentionned it in the commit message, sorry!
> 
> As I was mentionning to Andrew in the initial submission of this patch,
> this driver is a bit unusual since it represents a GMII to RGMII
> bridge, so it's not actually a PHY driver on its own -- it just sticks
> itself in between the actual PHY and the MAC.

Yes, my bad, you should still consider checking priv->phy_drv though, if
someone unbinds the PHY driver on either side, you are toast.

> 
> Cheers and thanks for the review,
> 
> Paul
> 
>>>  drivers/net/phy/xilinx_gmii2rgmii.c | 5 ++++-
>>>  1 file changed, 4 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/net/phy/xilinx_gmii2rgmii.c b/drivers/net/phy/xilinx_gmii2rgmii.c
>>> index 74a8782313cf..bd6084e315de 100644
>>> --- a/drivers/net/phy/xilinx_gmii2rgmii.c
>>> +++ b/drivers/net/phy/xilinx_gmii2rgmii.c
>>> @@ -44,7 +44,10 @@ static int xgmiitorgmii_read_status(struct phy_device *phydev)
>>>  	u16 val = 0;
>>>  	int err;
>>>  
>>> -	err = priv->phy_drv->read_status(phydev);
>>> +	if (priv->phy_drv->read_status)
>>> +		err = priv->phy_drv->read_status(phydev);
>>> +	else
>>> +		err = genphy_read_status(phydev);
>>>  	if (err < 0)
>>>  		return err;
>>>  
>>>
>>
>>


-- 
Florian