netdev - Re: Registering IRQ for MT7530 internal PHYs

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Message-ID: <11ca856b-1d0f-06ed-cf73-58fb9b757928@gmail.com>
Date:   Wed, 30 Dec 2020 17:53:40 +0100
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Florian Fainelli <f.fainelli@...il.com>,
        DENG Qingfang <dqfext@...il.com>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Andrew Lunn <andrew@...n.ch>, Jakub Kicinski <kuba@...nel.org>,
        Landen Chao <Landen.Chao@...iatek.com>,
        Marc Zyngier <maz@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Russell King <linux@...linux.org.uk>,
        Sean Wang <sean.wang@...iatek.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        linux-kernel@...r.kernel.org, netdev <netdev@...r.kernel.org>,
        Weijie Gao <weijie.gao@...iatek.com>,
        Chuanhong Guo <gch981213@...il.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        René van Dorst <opensource@...rst.com>
Subject: Re: Registering IRQ for MT7530 internal PHYs

On 30.12.2020 17:15, Florian Fainelli wrote:
> 
> 
> On 12/30/2020 1:12 AM, Heiner Kallweit wrote:
>> On 30.12.2020 10:07, DENG Qingfang wrote:
>>> Hi Heiner,
>>> Thanks for your reply.
>>>
>>> On Wed, Dec 30, 2020 at 3:39 PM Heiner Kallweit <hkallweit1@...il.com> wrote:
>>>> I don't think that's the best option.
>>>
>>> I'm well aware of that.
>>>
>>>> You may want to add a PHY driver for your chip. Supposedly it
>>>> supports at least PHY suspend/resume. You can use the RTL8366RB
>>>> PHY driver as template.
>>>
>>> There's no MediaTek PHY driver yet. Do we really need a new one just
>>> for the interrupts?
>>>
>> Not only for the interrupts. The genphy driver e.g. doesn't support
>> PHY suspend/resume. And the PHY driver needs basically no code,
>> just set the proper callbacks.
> 
> That statement about not supporting suspend/resume is not exactly true,
> the generic "1g" PHY driver only implements suspend/resume through the
> use of the standard BMCR power down bit, but not anything more
> complicated than that.
> 
Oh, right. Somehow I had in the back of my mind that the genphy driver
has no suspend/resume callbacks set.

> Interrupt handling within the PHY itself is not defined by the existing
> standard registers and will typically not reside in a standard register
> space either, so just for that reason you do need a custom PHY driver.
> There are other advantages if you need to expose additional PHY features
> down the road like PHY counters, energy detection, automatic power down etc.
> 
> I don't believe we will see discrete/standalone Mediatek PHY chips, but
> if that happens, then you would already have a framework for supporting
> them.
>