Re: RTC Chip and IRQ8 on 2.6.9

[Randy.Dunlap]

linux-os wrote:
> I must use the RTC and IRQ8 in a driver being ported from
> 2.4.20 to 2.6.9. When I attempt request_irq(8,...), it
> returns -EBUSY. I have disabled everything in .config
> that has "RTC" in it.
>
> The RTC interrupt is used to precisely time the sequencing
> of a precision A/D converter. It is mandatory that I use
> it because the precise interval is essential for its
> IIR filter that produces 20 bits of resolution from a
> 16 bit A/D.
>
>            CPU0
>   0:   60563767    IO-APIC-edge  timer
>   1:      57096    IO-APIC-edge  i8042
>   8:          1    IO-APIC-edge  rtc
>   9:          0   IO-APIC-level  acpi
>  12:         66    IO-APIC-edge  i8042
>  14:     112322    IO-APIC-edge  ide0
>  16:          0   IO-APIC-level  uhci_hcd, uhci_hcd
>  18:        640   IO-APIC-level  libata, uhci_hcd, Analogic Corp DLB
>  19:          0   IO-APIC-level  uhci_hcd
>  20:    4894484   IO-APIC-level  eth0
>  21:     110543   IO-APIC-level  aic7xxx
>  23:          0   IO-APIC-level  ehci_hcd
> NMI:          0 LOC:   60565403 ERR:          0
> MIS:          0
>
> This stuff works fine in 2.4.22 and, in fact, I'm the guy
> that added the global rtc_lock so that this very driver
> could run without interfering with anybody. Now, some code,
> somewhere (not in a module), has allocated the interrupt
> and generated exactly 1 interrupt. The kernel won't let
> me use that interrupt!
>
> How do I undo this so I can use my hardware on my machine?

I happen to be running a 2.6.9-rc1 kernel right now, with
an IO APIC (P4 UP), and no RTC support built into it,
and /proc/interrupts show IRQ 8 empty/unassigned:

           CPU0
  0:  777037582    IO-APIC-edge  timer
  1:     185323    IO-APIC-edge  i8042
  7:          0    IO-APIC-edge  parport0
  9:          0   IO-APIC-level  acpi
 12:    2838473    IO-APIC-edge  i8042
 14:    1197859    IO-APIC-edge  ide0
 15:         42    IO-APIC-edge  ide1
 17:         49   IO-APIC-level  aic7xxx, ohci_hcd
 19:          0   IO-APIC-level  uhci_hcd
 21:        197   IO-APIC-level  ohci1394, ohci_hcd, ohci_hcd, 
ohci_hcd, ohci_hc
d, ohci_hcd
 22:     832350   IO-APIC-level  ehci_hcd, eth0
 23:      16387   IO-APIC-level  es1371, uhci_hcd
NMI:          0
LOC:  776994543
ERR:          0
MIS:          0


Perhaps your .config and a simple test case would help.

--
~Randy
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/