linux-kernel - Re: [PATCH] x86: Get irq for hpet timer

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Message-ID: <4831A678.5070208@ladisch.de>
Date:	Mon, 19 May 2008 18:10:32 +0200
From:	Clemens Ladisch <clemens@...isch.de>
To:	Kevin Hao <kexin.hao@...driver.com>
CC:	venkatesh.pallipadi@...el.com, bob.picco@...com, mingo@...hat.com,
	tglx@...utronix.de, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86: Get irq for hpet timer

Kevin Hao wrote:
> +	for (irq = find_first_bit(&cap, HPET_MAX_IRQ); irq < HPET_MAX_IRQ;
> +		irq = find_next_bit(&cap, HPET_MAX_IRQ, 1 + irq)) {
> +		if (request_irq(irq, hpet_interrupt, irq_flags,
> +				devp->hd_name, (void *)devp))

This spams my log with interrupt sharing violations.  As long as we do
not know that the interrupt slot is empty, we need IRQF_PROBE_SHARED
here.

Another problem: the interrupt controller doesn't get correctly
initialized for some interrupt line that didn't already have some
routing:
| $ cat /proc/interrupts
|            CPU0
|   0:         63   IO-APIC-edge      timer
|   1:         96   IO-APIC-edge      i8042
|   2:          0    XT-PIC-XT        hpet2
|   6:          3   IO-APIC-edge      floppy
|   7:          0   IO-APIC-edge      parport0
|   8:          3   IO-APIC-edge      rtc
|   9:          0   IO-APIC-fasteoi   acpi
| ...

Additionally, I vaguely remember that on X86, there is some funny stuff
going on with interrupt lines 0, 2 and 8 which means that the interrupt
number passed to request_irq() is not necessarily identical to the
hardware interrupt line.

I don't know which of these problems is responsible, or if I'm totally
wrong, but on my machine, interrupts from hpet2 do not arrive.


Regards,
Clemens
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