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: Mon, 2 Mar 2020 00:20:41 +0100 [thread overview]
Message-ID: <a33c33d6-621a-4139-0e81-eb0d0fd0e095@gmail.com> (raw)
In-Reply-To: <a0b161ebd332c9ea26bb62ccf73d1862@walle.cc>
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.
> -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:[~2020-03-01 23:20 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 [this message]
2020-03-04 12:13 ` Heiner Kallweit
2020-03-04 13:02 ` Michael Walle
2020-03-02 3:05 ` David Miller
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=a33c33d6-621a-4139-0e81-eb0d0fd0e095@gmail.com \
--to=hkallweit1@gmail.com \
--cc=andrew@lunn.ch \
--cc=davem@davemloft.net \
--cc=f.fainelli@gmail.com \
--cc=linux@armlinux.org.uk \
--cc=michael@walle.cc \
--cc=netdev@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).