Re: [Qemu-ppc] [Qemu-devel] Disabling IRQ error

[Xie Xianshan]

Hi Max,
    Thanks for your patience and help.
    I`ve tried to do what you said, but the problem doesn`t go away.
And actually i cannot add a new register to the fpga device, because the 
fpga device i`m emulating already exists in the real world.
So i cannot change anything about hardware properties and linux driver 
for this device.

    By the way, how did you finally fix your problem?

Thanks,
 Simen

于 2013/09/11 17:29, Max Filippov 写道:
> On Wed, Sep 11, 2013 at 12:12 PM, Xie Xianshan<address@hidden>  wrote:
> >    I want to add a new device "fpga" for e500, and trigger an interrupt IRQ3
> > while the register BB_INTR_REG which belongs to device "fpga" is wrote by
> > the device driver of "fpga".
> >    For e500, IRQ3 is an external interrupt irq.
> >    According the debug log, the disabling error is encoutered during writing
> > BB_INTR_REG register.
> >    - write BB_INTR_REG register
> >        - qemu_irq_raise() is called.
> >        - after serval minutes,
> >          the error message about disabling irq is displayed.
> >    - continue the next execution without error(with poll?)
>
> So your device raises IRQ, but it doesn't lower it. Real devices
> usually don't do that, they either generate a short pulse on the
> IRQ line (in case of edge-triggered IRQ) or raise IRQ line on
> some event and then lower it on a command from its driver
> (level-triggered IRQ).
>
> You can do the following to make your device behave that way:
> - make your fpga device capable of lowering its IRQ, e.g. by adding
>    another register:
>
> > static void fpga_write(FPGAState *s, unsigned int offset, uint32_t value,
> > unsigned size) {
> >      switch(offset) {
> >      case BB_INTR_REG:
> >          qemu_irq_raise(s->irq);
> >          break;
>         case BB_INTC_REG:
>             qemu_irq_lower(s->irq);
>             break;
> >      }
> > }
>
> - provide an interrupt service routine in the linux driver for your fpga
>    device that would check whether the interrupt was caused by its
>    device, and if so lower the device's IRQ.
>
> Thanks.
> -- Max


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Best Regards
Xie Xianshan
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Xie Xianshan
Development Dept.I
Nanjing Fujitsu Nanda Software Tech. Co., Ltd.(FNST)
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