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

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Message-ID: <9bab7000-2f22-00e0-d92c-b80f3f41fab5@cogentembedded.com>
Date:   Mon, 9 Oct 2017 15:50:19 +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

On 10/09/2017 12:37 PM, Sergei Shtylyov 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.

    Here you are! Attaching both the patches against net-next.git...
Perhaps I also will be able to return to this subject in the near future...

MBR, Sergei

View attachment "phylib-add-device-reset-GPIO-support-v3.patch" of type "text/x-patch" (11599 bytes)

View attachment "macb-kill-PHY-reset-code-v3.patch" of type "text/x-patch" (2801 bytes)