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sparc64: Fix wedged irq regression.

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Kernel bugzilla 10273

As reported by Jos van der Ende, ever since commit
5a606b72a4 ("[SPARC64]: Do not ACK an
INO if it is disabled or inprogress.") sun4u interrupts
can get stuck.

What this changset did was add the following conditional to
the various IRQ chip ->enable() handlers on sparc64:

	if (unlikely(desc->status & (IRQ_DISABLED|IRQ_INPROGRESS)))
		return;

which is correct, however it means that special care is needed
in the ->enable() method.

Specifically we must put the interrupt into IDLE state during
an enable, or else it might never be sent out again.

Setting the INO interrupt state to IDLE resets the state machine,
the interrupt input to the INO is retested by the hardware, and
if an interrupt is being signalled by the device, the INO
moves back into TRANSMIT state, and an interrupt vector is sent
to the cpu.

The two sun4v IRQ chip handlers were already doing this properly,
only sun4u got it wrong.

Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller 2008-04-26 02:19:18 -07:00
parent c3bf9bc243
commit 227c331178
1 changed files with 2 additions and 1 deletions
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3
arch/sparc64/kernel/irq.c
View file

@ -1,6 +1,6 @@
/* irq.c: UltraSparc IRQ handling/init/registry.
*
* Copyright (C) 1997, 2007 David S. Miller (davem@davemloft.net)
* Copyright (C) 1997, 2007, 2008 David S. Miller (davem@davemloft.net)
* Copyright (C) 1998 Eddie C. Dost (ecd@skynet.be)
* Copyright (C) 1998 Jakub Jelinek (jj@ultra.linux.cz)
*/
@ -308,6 +308,7 @@ static void sun4u_irq_enable(unsigned int virt_irq)
IMAP_AID_SAFARI | IMAP_NID_SAFARI);
val |= tid | IMAP_VALID;
upa_writeq(val, imap);
upa_writeq(ICLR_IDLE, data->iclr);
}
}