From: Heiner Kallweit <hkallweit1@gmail.com>
To: Michael Walle <michael@walle.cc>
Cc: Andrew Lunn <andrew@lunn.ch>,
Florian Fainelli <f.fainelli@gmail.com>,
Russell King - ARM Linux <linux@armlinux.org.uk>,
David Miller <davem@davemloft.net>,
netdev@vger.kernel.org
Subject: Re: [PATCH net] net: phy: avoid clearing PHY interrupts twice in irq handler
Date: Wed, 4 Mar 2020 13:13:42 +0100 [thread overview]
Message-ID: <c2928823-da08-0321-6917-1481aab79e09@gmail.com> (raw)
In-Reply-To: <a33c33d6-621a-4139-0e81-eb0d0fd0e095@gmail.com>
On 02.03.2020 00:20, Heiner Kallweit wrote:
> On 01.03.2020 23:52, Michael Walle wrote:
>> Am 2020-03-01 21:36, schrieb Heiner Kallweit:
>>> On all PHY drivers that implement did_interrupt() reading the interrupt
>>> status bits clears them. This means we may loose an interrupt that
>>> is triggered between calling did_interrupt() and phy_clear_interrupt().
>>> As part of the fix make it a requirement that did_interrupt() clears
>>> the interrupt.
>>
>> Looks good. But how would you use did_interrupt() and handle_interrupt()
>> together? I guess you can't. At least not if handle_interrupt() has
>> to read the pending bits again. So you'd have to handle custom
>> interrupts in did_interrupt(). Any idea how to solve that?
>>
>> [I know, this is only about fixing the lost interrupts.]
>>
> Right, this one is meant for stable to fix the issue with the potentially
> lost interrupts. Based on it I will submit a patch for net-next that
> tackles the issue that did_interrupt() has to read (and therefore clear)
> irq status bits and therefore makes them unusable for handle_interrupt().
> The basic idea is that did_interrupt() is called only if handle_interrupt()
> isn't implemented. handle_interrupt() has to include the did_interrupt
> functionality. It can read the irq status once and store it in a variable
> for later use.
>
In case you wait for this patch to base further own work on it:
I'm waiting for next merge of net into net-next, because my patch will
apply cleanly only after that. This merge should happen in the next days.
>> -michael
>>
>>>
>>> The Fixes tag refers to the first commit where the patch applies
>>> cleanly.
>>>
>>> Fixes: 49644e68f472 ("net: phy: add callback for custom interrupt
>>> handler to struct phy_driver")
>>> Reported-by: Michael Walle <michael@walle.cc>
>>> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
>>> ---
>>> drivers/net/phy/phy.c | 3 ++-
>>> include/linux/phy.h | 1 +
>>> 2 files changed, 3 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
>>> index d76e038cf..16e3fb79e 100644
>>> --- a/drivers/net/phy/phy.c
>>> +++ b/drivers/net/phy/phy.c
>>> @@ -727,7 +727,8 @@ static irqreturn_t phy_interrupt(int irq, void *phy_dat)
>>> phy_trigger_machine(phydev);
>>> }
>>>
>>> - if (phy_clear_interrupt(phydev))
>>> + /* did_interrupt() may have cleared the interrupt already */
>>> + if (!phydev->drv->did_interrupt && phy_clear_interrupt(phydev))
>>> goto phy_err;
>>> return IRQ_HANDLED;
>>>
>>> diff --git a/include/linux/phy.h b/include/linux/phy.h
>>> index 80f8b2158..8b299476b 100644
>>> --- a/include/linux/phy.h
>>> +++ b/include/linux/phy.h
>>> @@ -557,6 +557,7 @@ struct phy_driver {
>>> /*
>>> * Checks if the PHY generated an interrupt.
>>> * For multi-PHY devices with shared PHY interrupt pin
>>> + * Set interrupt bits have to be cleared.
>>> */
>>> int (*did_interrupt)(struct phy_device *phydev);
>
next prev parent reply other threads:[~2020-03-04 12:13 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-01 20:36 [PATCH net] net: phy: avoid clearing PHY interrupts twice in irq handler Heiner Kallweit
2020-03-01 22:52 ` Michael Walle
2020-03-01 23:20 ` Heiner Kallweit
2020-03-04 12:13 ` Heiner Kallweit [this message]
2020-03-04 13:02 ` Michael Walle
2020-03-02 3:05 ` David Miller
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