linux-kernel - Re: [PATCH] net: phy: smsc: disable energy detect mode

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Message-ID: <56208D00.80707@denx.de>
Date:	Fri, 16 Oct 2015 07:37:04 +0200
From:	Heiko Schocher <hs@...x.de>
To:	Florian Fainelli <f.fainelli@...il.com>
Cc:	linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
	netdev@...r.kernel.org, Georg.Soffel@...ch-si.com
Subject: Re: [PATCH] net: phy: smsc: disable energy detect mode

Hello Florian,

Am 14.10.2015 um 06:17 schrieb Heiko Schocher:
> Hello Florian,
>
> Am 13.10.2015 um 21:26 schrieb Florian Fainelli:
>> On 12/10/15 22:13, Heiko Schocher wrote:
>>> On some boards the energy enable detect mode leads in
>>> trouble with some switches, so make the enabling of
>>> this mode configurable through DT.
>>>
>>> Signed-off-by: Heiko Schocher <hs@...x.de>
>>> ---
>>>
>>>   .../devicetree/bindings/net/smsc-lan87xx.txt       | 19 +++++++++++++++++
>>>   drivers/net/phy/smsc.c                             | 24 +++++++++++++++++-----
>>>   2 files changed, 38 insertions(+), 5 deletions(-)
>>>   create mode 100644 Documentation/devicetree/bindings/net/smsc-lan87xx.txt
>>>
>>> diff --git a/Documentation/devicetree/bindings/net/smsc-lan87xx.txt
>>> b/Documentation/devicetree/bindings/net/smsc-lan87xx.txt
>>> new file mode 100644
>>> index 0000000..39aa1dc
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/net/smsc-lan87xx.txt
>>> @@ -0,0 +1,19 @@
>>> +SMSC LAN87xx Ethernet PHY
>>> +
>>> +Some boards require special tuning values. Configure them
>>> +through an Ethernet OF device node.
>>> +
>>> +Optional properties:
>>> +
>>> +- disable-energy-detect:
>>> +  If set, do not enable energy detect mode for the SMSC phy.
>>> +  default: enable energy detect mode
>>
>> Although energy detection is something that is implemented by many PHYs,
>> I am not sure a generic property is suitable here, I would prefix that
>> with the SMSC vendor prefix here to make it clear this only applies to
>> this PHY.
>
> Hmm... but all PHYs should be able to enable, disable it in some way, or?

ping?

>> Would not you want to make it a reverse property here though, something
>> like this:
>>
>> smsc,energy-detect: boolean, when present indicates the PHY reliably
>> supports energy detection
>
> Yes, that was also my first thought, but currently, on this PHYs
> energy detect mode is on ... and if I introduce such a property,
> it will disable it for all existing boards, because property is
> missing ... so, maybe I break boards ...

I have a v2 prepared, but what to do here?

>>> +
>>> +Examples:
>>> +
>>> +    /* Attach to an Ethernet device with autodetected PHY */
>>> +    &cpsw_emac0 {
>>> +        phy_id = <&davinci_mdio>, <0>;
>>> +        phy-mode = "mii";
>>> +        disable-energy-detect;
>>> +    };
>>> diff --git a/drivers/net/phy/smsc.c b/drivers/net/phy/smsc.c
>>> index 70b0895..f90fbf3 100644
>>> --- a/drivers/net/phy/smsc.c
>>> +++ b/drivers/net/phy/smsc.c
>>> @@ -43,16 +43,30 @@ static int smsc_phy_ack_interrupt(struct phy_device *phydev)
>>>
>>>   static int smsc_phy_config_init(struct phy_device *phydev)
>>>   {
>>> +#ifdef CONFIG_OF
>>> +    int len;
>>> +    struct device *dev = &phydev->dev;
>>> +    struct device_node *of_node = dev->of_node;
>>
>> That does not need to be ifdefd out, at best annontate with __maybe_unused?
>
> Yes, I try it.

removed.

>>> +#endif
>>>       int rc = phy_read(phydev, MII_LAN83C185_CTRL_STATUS);
>>> +    int enable_energy = 1;
>>>
>>>       if (rc < 0)
>>>           return rc;
>>>
>>> -    /* Enable energy detect mode for this SMSC Transceivers */
>>> -    rc = phy_write(phydev, MII_LAN83C185_CTRL_STATUS,
>>> -               rc | MII_LAN83C185_EDPWRDOWN);
>>> -    if (rc < 0)
>>> -        return rc;
>>> +#ifdef CONFIG_OF
>>> +    if (!of_node && dev->parent->of_node)
>>> +        of_node = dev->parent->of_node;
>>
>> That looks strange, why would the property be placed at the parent level
>> when this is a PHY device tree node property?
>
> Hmm.. I recheck this.

Hmm.. the drivers/net/ethernet/ti/cpsw.c has no phy-handle
support ... I added this, so my v2 is now a patchset of 2 patches.

bye,
Heiko
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