From: Russell King - ARM Linux admin <linux@armlinux.org.uk>
To: Michael Walle <michael@walle.cc>
Cc: hkallweit1@gmail.com, andrew@lunn.ch, davem@davemloft.net,
f.fainelli@gmail.com, netdev@vger.kernel.org
Subject: Re: [PATCH net-next v2 2/3] net: phy: add callback for custom interrupt handler to struct phy_driver
Date: Tue, 19 Nov 2019 10:50:45 +0000 [thread overview]
Message-ID: <20191119105045.GY25745@shell.armlinux.org.uk> (raw)
In-Reply-To: <bd47f8e1ebc04fa98856ed8d89b91419@walle.cc>
On Tue, Nov 19, 2019 at 11:33:47AM +0100, Michael Walle wrote:
>
> Hi,
>
> this is an old thread and I know its already applied. But I'd like to hear
> your opinion on the following problem below.
>
> > The phylib interrupt handler handles link change events only currently.
> > However PHY drivers may want to use other interrupt sources too,
> > e.g. to report temperature monitoring events. Therefore add a callback
> > to struct phy_driver allowing PHY drivers to implement a custom
> > interrupt handler.
> >
> > Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
> > Suggested-by: Russell King - ARM Linux admin <linux@armlinux.org.uk>
> > Acked-by: Russell King <rmk+kernel@armlinux.org.uk>
> > ---
> > drivers/net/phy/phy.c | 9 +++++++--
> > include/linux/phy.h | 3 +++
> > 2 files changed, 10 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
> > index d90d9863e..068f0a126 100644
> > --- a/drivers/net/phy/phy.c
> > +++ b/drivers/net/phy/phy.c
> > @@ -772,8 +772,13 @@ static irqreturn_t phy_interrupt(int irq, void
> > *phy_dat)
> > if (phydev->drv->did_interrupt && !phydev->drv->did_interrupt(phydev))
> > return IRQ_NONE;
> >
> > - /* reschedule state queue work to run as soon as possible */
> > - phy_trigger_machine(phydev);
> > + if (phydev->drv->handle_interrupt) {
> > + if (phydev->drv->handle_interrupt(phydev))
> > + goto phy_err;
>
> There are PHYs which clears the interrupt already by reading the interrupt
> status register. To do something useful in handle_interrupt() I have to read
> the interrupt status register, thus clearing the pending interrupts.
>
>
> > + } else {
> > + /* reschedule state queue work to run as soon as possible */
> > + phy_trigger_machine(phydev);
> > + }
> >
> > if (phy_clear_interrupt(phydev))
> > goto phy_err;
>
> But here the interrupts are cleared again, which means we might loose
> interrupt causes in between.
>
> I could think of two different fixes:
> (1) handle_interrupt() has to take care to clear the interrupts and skip
> the phy_clear_interrupt() above.
> (2) handle_interrupt() might return a special return code which skips the
> phy_clear_interrupt
>
> TBH, I'd prefer (1) but I don't know if it is allowed to change semantics
> afterwards. (Also, I've found no driver where handle_interrupt() is actually
> used for now?)
I made the argument at the time that phylib should stop being a middle-
layer, but instead let PHY drivers take care of interrupt handling
themselves, just like we do elsewhere in the kernel. I think your
case just shows that trying to keep the interrupt handling structured
inside phylib and trying to make all PHYs fit is just going to be
painful.
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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next prev parent reply other threads:[~2019-11-19 10:50 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-30 13:08 [PATCH net-next v2 0/3] net: phy: improve handling of more complex C45 PHY's Heiner Kallweit
2019-05-30 13:09 ` [PATCH net-next v2 1/3] net: phy: enable interrupts when PHY is attached already Heiner Kallweit
2019-05-30 19:52 ` Andrew Lunn
2019-05-30 13:10 ` [PATCH net-next v2 2/3] net: phy: add callback for custom interrupt handler to struct phy_driver Heiner Kallweit
2019-11-19 10:33 ` Michael Walle
2019-11-19 10:50 ` Russell King - ARM Linux admin [this message]
2019-05-30 13:11 ` [PATCH net-next v2 3/3] net: phy: export phy_queue_state_machine Heiner Kallweit
2019-05-30 22:02 ` [PATCH net-next v2 0/3] net: phy: improve handling of more complex C45 PHY's David Miller
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