linux-kernel - Re: [PATCH] net: phy: realtek: clear interrupt during init for rtl8211f

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Date:   Fri, 15 May 2020 15:41:28 +0800
From:   Jisheng Zhang <Jisheng.Zhang@...aptics.com>
To:     Heiner Kallweit <hkallweit1@...il.com>
Cc:     Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        Russell King <linux@...linux.org.uk>,
        "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net: phy: realtek: clear interrupt during init for
 rtl8211f

On Thu, 14 May 2020 21:50:53 +0200 Heiner Kallweit wrote:

> 
> 
> On 14.05.2020 08:25, Jisheng Zhang wrote:
> > On Wed, 13 May 2020 20:45:13 +0200 Heiner Kallweit wrote:
> >  
> >>
> >> On 13.05.2020 08:51, Jisheng Zhang wrote:  
> >>> Hi,
> >>>
> >>> On Tue, 12 May 2020 20:43:40 +0200 Heiner Kallweit wrote:
> >>>  
> >>>>
> >>>>
> >>>> On 12.05.2020 12:46, Jisheng Zhang wrote:  
> >>>>> The PHY Register Accessible Interrupt is enabled by default, so
> >>>>> there's such an interrupt during init. In PHY POLL mode case, the
> >>>>> INTB/PMEB pin is alway active, it is not good. Clear the interrupt by
> >>>>> calling rtl8211f_ack_interrupt().  
> >>>>
> >>>> As you say "it's not good" w/o elaborating a little bit more on it:
> >>>> Do you face any actual issue? Or do you just think that it's not nice?  
> >>>
> >>>
> >>> The INTB/PMEB pin can be used in two different modes:
> >>> INTB: used for interrupt
> >>> PMEB: special mode for Wake-on-LAN
> >>>
> >>> The PHY Register Accessible Interrupt is enabled by
> >>> default, there's always such an interrupt during the init. In PHY POLL mode
> >>> case, the pin is always active. If platforms plans to use the INTB/PMEB pin
> >>> as WOL, then the platform will see WOL active. It's not good.
> >>>  
> >> The platform should listen to this pin only once WOL has been configured and
> >> the pin has been switched to PMEB function. For the latter you first would
> >> have to implement the set_wol callback in the PHY driver.
> >> Or where in which code do you plan to switch the pin function to PMEB?  
> >
> > I think it's better to switch the pin function in set_wol callback. But this
> > is another story. No matter WOL has been configured or not, keeping the
> > INTB/PMEB pin active is not good. what do you think?
> >  
> 
> It shouldn't hurt (at least it didn't hurt for the last years), because no
> listener should listen to the pin w/o having it configured before.
> So better extend the PHY driver first (set_wol, ..), and then do the follow-up
> platform changes (e.g. DT config of a connected GPIO).

There are two sides involved here: the listener, it should not listen to the pin
as you pointed out; the phy side, this patch tries to make the phy side
behave normally -- not keep the INTB/PMEB pin always active. The listener
side behaves correctly doesn't mean the phy side could keep the pin active.

When .set_wol isn't implemented, this patch could make the system suspend/resume
work properly.

PS: even with set_wol implemented as configure the pin mode, I think we
still need to clear the interrupt for phy poll mode either in set_wol
or as this patch does.