path: root/arch/mn10300/unit-asb2303
diff options
authorDavid Howells <>2008-10-01 13:47:06 +0100
committerLinus Torvalds <>2008-10-01 09:40:43 -0700
commitd6478fad430e37148b56f642c87301ba72476675 (patch)
treefe6378edf75342970ac171173dadf19309e3bbdc /arch/mn10300/unit-asb2303
parent7ac9c1c24c0e68bdb89524e8c99e13fffcb2fcfb (diff)
MN10300: Fix IRQ handling
Fix the IRQ handling on the MN10300 arch. This patch makes a number of significant changes: (1) It separates the irq_chip definition for edge-triggered interrupts from the one for level-triggered interrupts. This is necessary because the MN10300 PIC latches the IRQ channel's interrupt request bit (GxICR_REQUEST), even after the device has ceased to assert its interrupt line and the interrupt channel has been disabled in the PIC. So for level-triggered interrupts we need to clear this bit when we re-enable - which is achieved by setting GxICR_DETECT but not GxICR_REQUEST when writing to the register. Not doing this results in spurious interrupts occurring because calling mask_ack() at the start of handle_level_irq() is insufficient - it fails to clear the REQUEST latch because the device that caused the interrupt is still asserting its interrupt line at this point. (2) IRQ disablement [irq_chip::disable_irq()] shouldn't clear the interrupt request flag for edge-triggered interrupts lest it lose an interrupt. (3) IRQ unmasking [irq_chip::unmask_irq()] also shouldn't clear the interrupt request flag for edge-triggered interrupts lest it lose an interrupt. (4) The end() operation is now left to the default (no-operation) as __do_IRQ() is compiled out. This may affect misrouted_irq(), but according to Thomas Gleixner it's the correct thing to do. (5) handle_level_irq() is used for edge-triggered interrupts rather than handle_edge_irq() as the MN10300 PIC latches interrupt events even on masked IRQ channels, thus rendering IRQ_PENDING unnecessary. It is sufficient to call mask_ack() at the start and unmask() at the end. (6) For level-triggered interrupts, ack() is now NULL as it's not used, and there is no effective ACK function on the PIC. mask_ack() is now the same as mask() as the latch continues to latch, even when the channel is masked. Further, the patch discards the disable() op implementation as its now the same as the mask() op implementation, which is used instead. It also discards the enable() op implementations as they're now the same as the unmask() op implementations, which are used instead. Signed-off-by: David Howells <> Signed-off-by: Linus Torvalds <>
Diffstat (limited to 'arch/mn10300/unit-asb2303')
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/mn10300/unit-asb2303/unit-init.c b/arch/mn10300/unit-asb2303/unit-init.c
index 14b2c817cff8..70e8cb4ea266 100644
--- a/arch/mn10300/unit-asb2303/unit-init.c
+++ b/arch/mn10300/unit-asb2303/unit-init.c
@@ -51,7 +51,7 @@ void __init unit_init_IRQ(void)
switch (GET_XIRQ_TRIGGER(extnum)) {
- set_irq_handler(XIRQ2IRQ(extnum), handle_level_irq);
+ set_intr_postackable(XIRQ2IRQ(extnum));