netdev - Re: [PATCH] net: phy: realtek: Dummy IRQ calls for RTL8366RB

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Date:   Sun, 24 Feb 2019 01:14:57 +0100
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     Florian Fainelli <f.fainelli@...il.com>,
        netdev <netdev@...r.kernel.org>,
        Heiner Kallweit <hkallweit1@...il.com>
Subject: Re: [PATCH] net: phy: realtek: Dummy IRQ calls for RTL8366RB

On Sun, Feb 24, 2019 at 1:07 AM Andrew Lunn <andrew@...n.ch> wrote:

> > They are handled by the irqchip mask/unmask inside
> > the RTL8366RB, see:
> > drivers/net/dsa/rtl8366rb.c
> >
> > So as soon as the phy core request the threaded IRQ
> > the irqchip will deal with this business on its own.
> >
> > How exactly the RTL8366RB IRQ machine looks inside
> > I doubt even Realtek knows themselves, but from
> > my experiements, they seem all edge triggered,
> > and the irq will be raised every time an edge occurse
> > (such as inserting or removing the cable). The "ACK"
> > happens in hardware when we read the status register
> > in the nested interrupt handler in rtl8366rb_irq() so no
> > further registers need to be accessed.
>
> Hi Linus
>
> Thanks for the explanation. So dummy functions are fine in this case.
>
> However, in general, i don't think dummy functions will work for a PHY
> driver, and may lead to interrupt storms. So it might be better to
> have them in the driver, not the core, with comments about why they
> are safe.

OK shall I just send a v3 moving them back to the driver so we avoid
confusion on which version should be applied?

Yours,
Linus Walleij