[SOLVED] PCIe IRQ problem

mukiwa · 09-03-2013, 06:36 AM

Hi,

I am writing a device driver for a new PCIe device. The IRQ associated with this device is #11 as can be seen in /proc/interrupts:

"11: 0 0 0 0 IR-IO-APIC-edge vfb"

However whenever the new device generates an interrupt it looks as if IRQ #16 is raised instead as can be seen by dmesg:

[ 7963.019683] irq 16: nobody cared (try booting with the "irqpoll" option)
[ 7963.019690] Pid: 0, comm: swapper/1 Tainted: GF O 3.8.0-29-generic #42-Ubuntu
[ 7963.019692] Call Trace:
[ 7963.019694] <IRQ> [<ffffffff810ece5d>] __report_bad_irq+0x3d/0xe0
[ 7963.019707] [<ffffffff810ed322>] note_interrupt+0x1c2/0x210
[ 7963.019712] [<ffffffff81574b98>] ? cpuidle_wrap_enter+0x58/0xa0
[ 7963.019716] [<ffffffff81574150>] ? centrino_target+0x370/0x370
[ 7963.019720] [<ffffffff810eaa97>] handle_irq_event_percpu+0xa7/0x1f0
[ 7963.019724] [<ffffffff81574150>] ? centrino_target+0x370/0x370
[ 7963.019727] [<ffffffff810eac2e>] handle_irq_event+0x4e/0x80
[ 7963.019731] [<ffffffff810ede6a>] handle_fasteoi_irq+0x5a/0x100
[ 7963.019737] [<ffffffff810164ce>] handle_irq+0x1e/0x30
[ 7963.019741] [<ffffffff816d732a>] do_IRQ+0x5a/0xe0
[ 7963.019745] [<ffffffff816cd32d>] common_interrupt+0x6d/0x6d
[ 7963.019747] <EOI> [<ffffffff81574b98>] ? cpuidle_wrap_enter+0x58/0xa0
[ 7963.019754] [<ffffffff81574bf0>] cpuidle_enter_tk+0x10/0x20
[ 7963.019757] [<ffffffff815747e5>] cpuidle_idle_call+0xa5/0x260
[ 7963.019761] [<ffffffff8101d5af>] cpu_idle+0xaf/0x120
[ 7963.019765] [<ffffffff816b6a83>] start_secondary+0x1e0/0x1e5
[ 7963.019767] handlers:
[ 7963.019771] [<ffffffff814fa0b0>] usb_hcd_irq
[ 7963.019773] Disabling IRQ #16

Is this a driver problem (me setting up the interrupt handling incorrectly), or a device problem (I should blame the HW engineer for raising the wrong IRQ)?

Thanks,
David

Mara · 09-09-2013, 03:28 PM

The device is rising the interrupt 16. /proc/interrupts shows the software view, not the hardware one (on most platforms there is no way to find out which interrupt is connected where other than rising it). /proc/interrupts in this case says that you have installed your driver for irq 11.

For me it looks like a communication problem with the hardware engineer. Did you talk in decimal or in hexadecimal? 11 is too close to 0x11, which is 17, counted from 0 it makes 16...

mukiwa · 09-11-2013, 12:17 PM

Thanks, I tried MSI interrupts which I discovered is supported by the device and then things started working.