netdev - Re: [PATCHv4 2/5] net: phy: extend fixed driver with fixed_phy

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Message-ID: <55E8A5AD.4050908@cogentembedded.com>
Date:	Thu, 3 Sep 2015 22:55:25 +0300
From:	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To:	Florian Fainelli <florian@...nwrt.org>,
	Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
	"David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
	devicetree@...r.kernel.org
Cc:	Tawfik Bayouk <tawfik@...vell.com>,
	Nadav Haklai <nadavh@...vell.com>,
	Lior Amsalem <alior@...vell.com>,
	Gregory Clement <gregory.clement@...e-electrons.com>,
	Ezequiel Garcia <ezequiel.garcia@...e-electrons.com>,
	linux-arm-kernel@...ts.infradead.org,
	Grant Likely <grant.likely@...retlab.ca>,
	Rob Herring <robh+dt@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Christian Gmeiner <christian.gmeiner@...il.com>
Subject: Re: [PATCHv4 2/5] net: phy: extend fixed driver with
 fixed_phy_register()

On 09/03/2015 10:38 PM, Florian Fainelli wrote:

>>>> The existing fixed_phy_add() function has several drawbacks that
>>>> prevents it from being used as is for OF-based declaration of fixed
>>>> PHYs:
>>>>
>>>>    * The address of the PHY on the fake bus needs to be passed, while a
>>>>      dynamic allocation is desired.
>>>>
>>>>    * Since the phy_device instantiation is post-poned until the next
>>>>      mdiobus scan, there is no way to associate the fixed PHY with its
>>>>      OF node, which later prevents of_phy_connect() from finding this
>>>>      fixed PHY from a given OF node.
>>>>
>>>> To solve this, this commit introduces fixed_phy_register(), which will
>>>> allocate an available PHY address, add the PHY using fixed_phy_add()
>>>> and instantiate the phy_device structure associated with the provided
>>>> OF node.
>>>>
>>>> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>
>>>> Acked-by: Florian Fainelli <f.fainelli@...il.com>
>>>> Acked-by: Grant Likely <grant.likely@...aro.org>
>>>> ---
>>>>    drivers/net/phy/fixed.c   | 61
>>>> +++++++++++++++++++++++++++++++++++++++++++++++
>>>>    include/linux/phy_fixed.h | 11 +++++++++
>>>>    2 files changed, 72 insertions(+)
>>>>
>>>> diff --git a/drivers/net/phy/fixed.c b/drivers/net/phy/fixed.c
>>>> index e41546d..d60d875 100644
>>>> --- a/drivers/net/phy/fixed.c
>>>> +++ b/drivers/net/phy/fixed.c
>>> [...]
>>>> @@ -203,6 +204,66 @@ err_regs:
>>> [...]
>>>> +int fixed_phy_register(unsigned int irq,
>>>> +               struct fixed_phy_status *status,
>>>> +               struct device_node *np)
>>>> +{
>>>> +    struct fixed_mdio_bus *fmb = &platform_fmb;
>>>> +    struct phy_device *phy;
>>>> +    int phy_addr;
>>>> +    int ret;
>>>> +
>>>> +    /* Get the next available PHY address, up to PHY_MAX_ADDR */
>>>> +    spin_lock(&phy_fixed_addr_lock);
>>>> +    if (phy_fixed_addr == PHY_MAX_ADDR) {
>>>> +        spin_unlock(&phy_fixed_addr_lock);
>>>> +        return -ENOSPC;
>>>> +    }
>>>> +    phy_addr = phy_fixed_addr++;
>>>> +    spin_unlock(&phy_fixed_addr_lock);
>>>> +
>>>> +    ret = fixed_phy_add(PHY_POLL, phy_addr, status);
>>>
>>>      Was rummaging in the fixed_phy driver and a bug sprang right at
>>> me: 'phy'
>>
>>     Sorry, s/phy/irq/ of course. Just noticed. :-/

    I've reported the bug on #miplsinux, there I used the correct word. :-)

> Ok, that makes sense then, and yes, this "irq" argument should have been
> passed down to fixed_phy_add(). Might be worth adding a WARN_ON(irq !=
> PHY_POLL) just to catch callers that expect something else.

    In-tree callers all seem to pass PHY_POLL to fixed_phy_register(). Do we 
care about out of tree stuff?

> Thanks!
> --
> Florian

MBR, Sergei

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