Re: [PATCH] x86/ioapic: add IO-APIC irq_chip retrigger hook
From: Ruslan Ruslichenko -X (rruslich - GLOBALLOGIC INC at Cisco)
Date: Wed Jan 18 2017 - 09:26:23 EST
On 01/18/2017 12:46 PM, Thomas Gleixner wrote:
On Tue, 17 Jan 2017, Ruslan Ruslichenko wrote:
After commit d32932d02e18 ("x86/irq: Convert IOAPIC to use hierarchical
irqdomain interfaces") IO-APIC is switched to hierarchical irqdomain
implementation. Also this patch removed irq_retrigger hook for IO-APIC
chip which seem to be wrong. Without this hook some edge-triggered irq's
might be lost, since kernel uses it to retrigger edge irq's triggered
while they are being handled or disabled by driver
Restoring the callbacks is the right thing to do, but there is no problem
because if the retrigger callback is empty then pending edge interrupts are
resent by software. It's just less efficient, but not a issue.
Software resend will only work if CONFIG_HARDIRQS_SW_RESEND is enabled,
which is not selected for x86 architectures.
So it's good that patch now picked up.
Thanks,
tglx