[PATCH] x86: Fix S3 resume for HPET MSI IRQ case (RE: [Xen-devel] x86 HPET MSI IRQs vs resume from S3)

["Jan Beulich" <JBeulich@xxxxxxxxxx>]

>>> On 14.02.11 at 10:30, "Wei, Gang" <gang.wei@xxxxxxxxx> wrote:
> x86: Fix S3 resume for HPET MSI IRQ case
> 
> Jan Beulich found that for S3 resume on platforms without ARAT feature but 
> with MSI capable HPET, request_irq() will be called in hpet_setup_msi_irq() 
> for irq already setup(no release_irq() called during S3 suspend), so that 
> always falling back to using legacy_hpet_event.
> 
> Fix it by conditional calling request_irq() for 4.1. Planned to split the S3 
> resume path from booting path post 4.1, as Jan suggested.
> 
> Signed-off-by: Wei Gang <gang.wei@xxxxxxxxx>

Acked-by: Jan Beulich <jbeulich@xxxxxxxxxx>

> diff -r 67f2fed57034 xen/arch/x86/hpet.c
> --- a/xen/arch/x86/hpet.c       Fri Feb 11 18:22:37 2011 +0000
> +++ b/xen/arch/x86/hpet.c       Tue Feb 15 14:48:54 2011 +0800
> @@ -367,12 +367,20 @@ static int hpet_setup_msi_irq(unsigned i
>      int ret;
>      struct msi_msg msg;
>      struct hpet_event_channel *ch = &hpet_events[irq_to_channel(irq)];
> -
> -    irq_desc[irq].handler = &hpet_msi_type;
> -    ret = request_irq(irq, hpet_interrupt_handler,
> -                      0, "HPET", ch);
> -    if ( ret < 0 )
> -        return ret;
> +    irq_desc_t *desc = irq_to_desc(irq);
> +
> +    if ( desc->handler == &no_irq_type )
> +    {
> +        desc->handler = &hpet_msi_type;
> +        ret = request_irq(irq, hpet_interrupt_handler,
> +                          0, "HPET", ch);
> +        if ( ret < 0 )
> +            return ret;
> +    }
> +    else if ( desc->handler != &hpet_msi_type )
> +    {
> +        return -EINVAL;
> +    }
>  
>      msi_compose_msg(NULL, irq, &msg);
>      hpet_msi_write(irq, &msg);
> 
> Jimmy
> 
> Jan Beulich wrote on 2011-01-28:
>> Going through hpet_broadcast_init(), I see that hpet_setup_msi_irq()
>> gets called during resume, thus causing setup_irq() to be called. I'm
>> failing to spot the corresponding release_irq(), and hence I can't see
>> how this whole code path is supposed to work during resume (other than
>> always falling back to using legacy_hpet_event). Instead I'm wondering
>> whether in the resume case only msi_compose_msg()/
>> hpet_msi_write() should be called for each IRQ used rather than the
>> whole hpet_broadcast_init().




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