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.ang...@bell.net>
Fixes: dc30c35be720 ("net: dsa: mv88e6xxx: Implement interrupt support.")
Tested-by: Andrew Lunn <and...@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.
Andrew
