From: David Miller <davem@davemloft.net>
To: andrew@lunn.ch
Cc: dave.anglin@bell.net, linux@arm.linux.org.uk,
vivien.didelot@savoirfairelinux.com, f.fainelli@gmail.com,
netdev@vger.kernel.org
Subject: Re: [PATCH net] dsa: mv88e6xxx: Ensure all pending interrupts are handled prior to exit
Date: Wed, 13 Feb 2019 20:47:31 -0800 (PST) [thread overview]
Message-ID: <20190213.204731.2262809689964875254.davem@davemloft.net> (raw)
In-Reply-To: <20190214020723.GE24589@lunn.ch>
From: Andrew Lunn <andrew@lunn.ch>
Date: Thu, 14 Feb 2019 03:07:23 +0100
> On Mon, Feb 11, 2019 at 01:40:21PM -0500, John David Anglin wrote:
>> The GPIO interrupt controller on the espressobin board only supports edge interrupts.
>> If one enables the use of hardware interrupts in the device tree for the 88E6341, it is
>> possible to miss an edge. When this happens, the INTn pin on the Marvell switch is
>> stuck low and no further interrupts occur.
>>
>> I found after adding debug statements to mv88e6xxx_g1_irq_thread_work() that there is
>> a race in handling device interrupts (e.g. PHY link interrupts). Some interrupts are
>> directly cleared by reading the Global 1 status register. However, the device interrupt
>> flag, for example, is not cleared until all the unmasked SERDES and PHY ports are serviced.
>> This is done by reading the relevant SERDES and PHY status register.
>>
>> The code only services interrupts whose status bit is set at the time of reading its status
>> register. If an interrupt event occurs after its status is read and before all interrupts
>> are serviced, then this event will not be serviced and the INTn output pin will remain low.
>>
>> This is not a problem with polling or level interrupts since the handler will be called
>> again to process the event. However, it's a big problem when using level interrupts.
>>
>> The fix presented here is to add a loop around the code servicing switch interrupts. If
>> any pending interrupts remain after the current set has been handled, we loop and process
>> the new set. If there are no pending interrupts after servicing, we are sure that INTn has
>> gone high and we will get an edge when a new event occurs.
>>
>> Tested on espressobin board.
>>
>> Signed-off-by: John David Anglin <dave.anglin@bell.net>
>
> Fixes: dc30c35be720 ("net: dsa: mv88e6xxx: Implement interrupt support.")
>
> Tested-by: Andrew Lunn <andrew@lunn.ch>
>
> David, please ensure that Heiner's patch:
>
> net: phy: fix interrupt handling in non-started states
>
> is applied first. Otherwise we can get into an interrupt storm.
Ok, all done.
Should I queue just this one for -stable? I didn't queue up Heiner's change for
-stable because it fixes a 5.0-rcX regression.
next prev parent reply other threads:[~2019-02-14 4:47 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-22 19:16 net: phylink: dsa: mv88e6xxx: flaky link detection on switch ports with internal PHYs John David Anglin
2019-01-22 20:28 ` Andrew Lunn
2019-01-22 21:40 ` John David Anglin
2019-01-22 22:36 ` Andrew Lunn
2019-01-22 23:52 ` John David Anglin
2019-01-23 0:11 ` John David Anglin
2019-01-23 0:22 ` Andrew Lunn
2019-01-25 16:30 ` John David Anglin
2019-01-25 16:48 ` Russell King - ARM Linux admin
2019-01-25 18:38 ` John David Anglin
2019-01-30 17:08 ` John David Anglin
2019-01-30 17:28 ` Andrew Lunn
2019-01-30 19:01 ` John David Anglin
2019-01-30 19:09 ` Andrew Lunn
2019-01-30 22:24 ` John David Anglin
2019-01-30 22:38 ` Andrew Lunn
2019-01-31 1:27 ` John David Anglin
2019-01-31 17:27 ` John David Anglin
2019-02-04 18:37 ` [PATCH] net: phylink: dsa: mv88e6xxx: Revise irq setup ordering John David Anglin
2019-02-04 19:35 ` Andrew Lunn
2019-02-04 19:52 ` John David Anglin
2019-02-04 20:19 ` Andrew Lunn
2019-02-04 21:38 ` John David Anglin
2019-02-04 22:47 ` Andrew Lunn
2019-02-04 21:59 ` [PATCH v2] net: " John David Anglin
2019-02-04 23:14 ` Andrew Lunn
2019-02-05 0:38 ` John David Anglin
2019-02-05 2:21 ` Andrew Lunn
2019-02-05 19:20 ` John David Anglin
2019-02-05 19:54 ` Andrew Lunn
2019-02-05 18:37 ` David Miller
2019-02-11 18:40 ` [PATCH net] dsa: mv88e6xxx: Ensure all pending interrupts are handled prior to exit John David Anglin
2019-02-11 23:33 ` Andrew Lunn
2019-02-12 0:57 ` John David Anglin
2019-02-12 1:21 ` Andrew Lunn
2019-02-12 3:58 ` Andrew Lunn
2019-02-12 6:51 ` Heiner Kallweit
2019-02-12 12:56 ` Andrew Lunn
2019-02-12 18:42 ` Heiner Kallweit
2019-02-12 20:09 ` John David Anglin
2019-02-12 16:30 ` Russell King - ARM Linux admin
2019-02-12 20:11 ` Heiner Kallweit
2019-02-12 20:54 ` Heiner Kallweit
2019-02-12 22:55 ` Russell King - ARM Linux admin
2019-02-14 2:07 ` Andrew Lunn
2019-02-14 4:47 ` David Miller [this message]
2019-02-14 4:50 ` Andrew Lunn
2019-02-14 15:27 ` David Miller
2019-01-22 23:12 ` net: phylink: dsa: mv88e6xxx: flaky link detection on switch ports with internal PHYs Andrew Lunn
2019-01-22 23:48 ` John David Anglin
2019-01-23 0:00 ` John David Anglin
2019-01-23 0:04 ` Florian Fainelli
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