> So the PHY is level based. The PHY is combing multiple interrupt sources > into one external interrupt. If any of those internal interrupt sources are > active, the external interrupt is active. If there are > multiple active sources > at once, the interrupt stays low, until they are all cleared. This means > there is not an edge per interrupt. There is one edge when the first internal > source occurs, and no more edges, > even if there are more internal interrupts. > The general flow in the PHY interrupt handler is to read the interrupt status > register, which tells you which internal interrupts have fired. You then > address these internal interrupts one by one. In KSZ9031, Register MII_KSZPHY_INTCS=0x1B reports all interrupt events and clear on read. So if there are 4 different interrupts, once it is read once, all 4 clear at once. The micrel.c driver has defined ack_interrupt to read the above reg and is called every time the interrupt handler phy_interrupt is called. So in this case, we should be good. The code flow in our case would look like this: - 2 interrupt sources (for example, link down followed by link up) set in MII_KSZPHY_INTCS - interrupt handler (phy_interrupt) reads MII_KSZPHY_INT which automatically clears both interrupts - another internal source triggers and sets the register. - The second edge will be caught accordingly by the GPIO. > This can take some time, MDIO is a slow bus etc. While handling these interrupt sources, > it could be another internal interrupt source triggers. This new internal interrupt source > keeps the external interrupt active. But there has not been an edge, since the interrupt > handler is still clearing the sources which caused the first interrupt. With level interrupts, > this is not an issue. When the interrupt handler exits, the interrupt is re-enabled. Since it > is still active, due to the unhandled internal interrupt sources, the level interrupt > immediately fires again. the handler then sees this new interrupt and handles it. > At that point the level interrupt goes inactive.
