Re: usb interrupt conflict with RTAI

Hi Paolo, 
thanks for the feedback. 
The system is a production system (ALMA Telescope)
so upgrading is really not an option unfortunately. (at least for now).

Digging into the RT-Net code meanwhile I found that in e1000_main.c (the 
driver I'm using for my NIC) is not propagating interrupts he don't owns.

i.e. in the interrupt service routine I changed the following code:
      if (unlikely(!icr)) {
        return RTDM_IRQ_NONE;  /* Not our interrupt */
        }
to 
        if (unlikely(!icr)) {
        return XN_ISR_PROPAGATE;  /* Not our interrupt */
        }
So in other words I use the feature you described. 
This solved the issue. Now we are testing and validating. I hope there are no 
bad side-effects surprises.


I have not well understood what you mean with "... , but
just int he case they know its kind and what is it for..."""

Do you thing the change I did to the driver is kind of hazard?

Thanks
Dietrich

On Wednesday 23 August 2017 16:06:36 Paolo Mantegazza wrote:
> RTAI, and so RTDM,  can pend (pass) an interrupt they use down to Linux, but
> jjust int he case they know its kind and what is it for. In Clearly in your
> case it is not so, In your case I see that you are using very old versions
> for both RTAI and Linux. My suggestion is to upgrade both and see what
> happens.By way of example, if your hartdware is not really really old it is
> possible that using the APIC under UP coupled to MSI support could solve
> the problem, without caring of anything else.
> 
> Paolo
> ________________________________________
> From: Rtai [[email protected]] on behalf of Dietrich Pescoller
> [[email protected]] Sent: Tuesday, August 22, 2017 11:40 AM
> To: [email protected]
> Subject: [Rtai] usb interrupt conflict with RTAI
> 
> Dear all,
> 
> I'm facing an issue with shared interrupts
> 
> The problem I have is that i wanted to integrate a USB-stick for storage,
> but my USB system is conflicting with the RTAI system.
> 
> As soon as I load the usb-storage.ko module I get the following message from
> the
> kernel:
>         RTDM: xnintr_irq_handler: IRQ11 not handled. Disabling IRQ line.
> 
> After this message the system system stops working, i.e. no RT ethernet
> packets are received anymore.
> 
> My setup is quite old and is as follow:
> - Linux Kernel 2.6.19.7
> - rtai-3.6
> - rtnet-0.9.11
> 
> looking at /proc/interrupts
> ====
>   0:     108824    XT-PIC-XT        timer, rtai_broadcast
>   1:          8    XT-PIC-XT        i8042
>   2:          0    XT-PIC-XT        cascade
>   4:          0    XT-PIC-XT        tpmc901drv
>   7:       2392    XT-PIC-XT        eth0
>   9:          0     XT-PIC-XT        uhci_hcd:usb2
>  11:         28   XT-PIC-XT        uhci_hcd:usb1  <--- conflicting interrupt
> 12:          3    XT-PIC-XT        i8042
>  14:          0    XT-PIC-XT        libata
>  15:       1773    XT-PIC-XT        libata
> NMI:          1
> LOC:     108794
> ERR:          0
> MIS:          0
> 
> and /proc/rtai/hal
> ====
> 
> ** Real-time IRQs used by RTAI:
> 
>     #3 at e00ab290
>     #4 at e00e3279
>     #11 at e3b85420    <--- conflicting interrupt
>     #215 at e00cbb80
>     #216 at e00cb2d0
> 
> I see that the irq #11 is shared between an Ethernet NIC and the USB, and
> something is not handled properly. The Ethernet NIC is in handled by a RTNET
> driver i.e. e1000.ko.
> 
> I searched for a possibility to remap this interrupt in the BIOS of my board
> but unfortunately there seems to be no option for that.
> 
> I see here the following possible solutions but I did not found a way manage
> them (I'm still blocked in the teory...)
> 
> 1) try to understand why the shared interrupt #11 is not forwarded to linux,
> is probably a rtnet e1000 driver issue... avoiding RTDM to disable the IRQ
> line.
> 2) remap the interrupt by software, I don't know if this is possible...
> 
> Many thanks in advance for your help/advices
> 
> Bye,
> Dietrich
> _______________________________________________
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> [email protected]
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