Re: Most interrupts are edge-triggered, non-APIC system

[Daniel Drake <dsd@gentoo.org>]

Bjorn Helgaas wrote:
> On Thursday 01 June 2006 15:04, Daniel Drake wrote:
>> João Oliveirinha reported a bug related to the sky2 network driver on 
>> the Gentoo bugzilla. Stephen Hemminger (sky2 author) kindly helped 
>> diagnose the issues, and he believes that one of the reasons why things 
>> are running sub-optimally is because the interrupt assigned to sky2 is 
>> edge-triggered (NAPI requires things to be level-triggered).
> 
> I'm not convinced that the sky2 interrupt is edge-triggered.

Thanks for the explanation, that makes sense. Stephen, you might be 
interested in this: (don't worry, nothing is broken!)

> The "ELCR" line:
>   ACPI: setting ELCR to 0200 (from 0c20)
> only shows the ELCR state early during boot when we're setting
> up the ACPI SCI interrupt.
> 
> Interrupts can also be set to level-triggered mode later, when
> the driver claims the device.  This in the acpi_register_gsi() ->
> eisa_set_level_irq() path and prints a different message.
> 
> Attachment http://bugs.gentoo.org/attachment.cgi?id=85619&action=view
> shows that sky2 should be on IRQ11, and it should be level-triggered:
> 
>   ACPI: PCI Interrupt Link [LNKA] enabled at IRQ 11
>   PCI: setting IRQ 11 as level-triggered
>   ACPI: PCI Interrupt 0000:00:01.0[A] -> Link [LNKA] -> GSI 11 (level, low) -> IRQ 11
>   ...
>   ACPI: PCI Interrupt 0000:02:00.0[A] -> Link [LNKA] -> GSI 11 (level, low) -> IRQ 11
>   PCI: Setting latency timer of device 0000:02:00.0 to 64
>   sky2 v0.15 addr 0xbc000000 irq 11 Yukon-FE (0xb7) rev 1
> 
> (sky2 shares the interrupt with other devices, so we set IRQ 11
> to be level-triggered when we enable the interrupt for one of
> the other devices, so the "setting IRQ 11 as level-triggered"
> message is earlier than the sky2 driver init.)

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