netdev - Re: [PATCH 2/4] ravb: Add optional PHY reset during system resume

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Date:   Mon, 9 Oct 2017 12:37:36 +0300
From:   Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To:     Florian Fainelli <f.fainelli@...il.com>,
        Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Geert Uytterhoeven <geert+renesas@...der.be>,
        "David S . Miller" <davem@...emloft.net>,
        Simon Horman <horms@...ge.net.au>,
        Magnus Damm <magnus.damm@...il.com>,
        Andrew Lunn <andrew@...n.ch>,
        Niklas Söderlund 
        <niklas.soderlund+renesas@...natech.se>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Subject: Re: [PATCH 2/4] ravb: Add optional PHY reset during system resume

Hello!

On 10/1/2017 7:34 PM, Florian Fainelli wrote:

>>>>>> If the optional "reset-gpios" property is specified in DT, the generic
>>>>>> MDIO bus code takes care of resetting the PHY during device probe.
>>>>>> However, the PHY may still have to be reset explicitly after system
>>>>>> resume.
>>>>>>
>>>>>> This allows to restore Ethernet operation after resume from s2ram on
>>>>>> Salvator-XS, where the enable pin of the regulator providing PHY power
>>>>>> is connected to PRESETn, and PSCI suspend powers down the SoC.
>>>>>>
>>>>>> Signed-off-by: Geert Uytterhoeven <geert+renesas@...der.be>
>>>>>> ---
>>>>>>    drivers/net/ethernet/renesas/ravb_main.c | 9 +++++++++
>>>>>>    1 file changed, 9 insertions(+)
>>>>>>
>>>>>> diff --git a/drivers/net/ethernet/renesas/ravb_main.c
>>>>>> b/drivers/net/ethernet/renesas/ravb_main.c
>>>>>> index fdf30bfa403bf416..96d1d48e302f8c9a 100644
>>>>>> --- a/drivers/net/ethernet/renesas/ravb_main.c
>>>>>> +++ b/drivers/net/ethernet/renesas/ravb_main.c
>> [...]
>>>>>> @@ -2302,6 +2304,13 @@ static int __maybe_unused ravb_resume(struct
>>>>>> device *dev)he patches
>>>>>>          * reopen device if it was running before system suspended.
>>>>>>          */
>>>>>>
>>>>>> +     /* PHY reset */
>>>>>> +     if (bus->reset_gpiod) {
>>>>>> +             gpiod_set_value_cansleep(bus->reset_gpiod, 1);
>>>>>> +             udelay(bus->reset_delay_us);
>>>>>> +             gpiod_set_value_cansleep(bus->reset_gpiod, 0);
>>>>>> +     }
>>>>>
>>>>> This is a clever hack, but unfortunately this is also misusing the MDIO
>>>>> bus reset line into a PHY reset line. As commented in patch 3, if this
>>>>> reset line is tied to the PHY, then this should be a PHY property and
>>>>
>>>> OK.
>>>>
>>>>> you cannot (ab)use the MDIO bus GPIO reset logic anymore...
>>>>
>>>> And then I should add reset-gpios support to drivers/net/phy/micrel.c?
>>>> Or is there already generic code to handle per-PHY reset? I couldn't
>>>> find it.
>>>
>>> There is not such a thing unfortunately, but it would presumably be
>>
>>     It's strange you don't remember about my (abandoned) patches to
>> handle per=PHY reset GPIOs -- perhaps it's time to unearth them. Here
>> they are:
>>
>> http://patchwork.ozlabs.org/patch/616495/
>> http://patchwork.ozlabs.org/patch/616501/
>>
>>     I had v3 in the works before abandoning this series -- it doesn't
>> apply now.
> 
> Should Geert pick-up where you left and address the feedback given in
> v2, or do you plan to post a rebased v3?

    I was going to address the rejects in v3 and give the patchset to Geert... 
unfortunately, this took so-o-o long. I'm going to do it today, at last.

[...]

MBR, Sergei