Re: [PATCH V3 1/3] ACPI, PCI IRQ: add PCI_USING penalty for ISA interrupts

Sinan Kaya
2016-10-18T15:32:44Z

Sorry, I think I didn't have enough morning coffee.

Looking at these again and trying to be specific.

On 10/18/2016 8:20 AM, Sinan Kaya wrote:
> It seems wrong to me that we call acpi_irq_get_penalty() from
>> acpi_irq_penalty_update() and acpi_penalize_isa_irq(). It seems like they
>> should just manipulate acpi_isa_irq_penalty[irq] directly.
>>
>> acpi_irq_penalty_update() is for command-line parameters, so it certainly
>> doesn't need the acpi_irq_pci_sharing_penalty() information (the
>> acpi_link_list should be empty at the time we process the command-line
>> parameters).

Calling acpi_irq_get_penalty for ISA IRQ is OK as long as it doesn't have
any dynamic IRQ calculation such that acpi_isa_irq_penalty[irq] = acpi_irq_get_penalty.

If this is broken, then we need special care so that we don't assign
dynamically calcualted sci_penalty back to acpi_isa_irq_penalty[irq]. This
results in returning incorrect penalty as

acpi_irq_get_penalty = acpi_isa_irq_original_penalty[irq] + 2 * sci_penalty.

Now that we added sci_penalty into the acpi_irq_get_penalty function,
calling acpi_irq_get_penalty is not correct anymore. This line here needs to
be replaced with acpi_isa_irq_penalty[irq] as you suggested.

if (used)
new_penalty = acpi_irq_get_penalty(irq) +
PIRQ_PENALTY_ISA_USED;
else
new_penalty = 0;

acpi_isa_irq_penalty[irq] = new_penalty;

>>
>> acpi_penalize_isa_irq() is telling us that a PNP or ACPI device is using
>> the IRQ -- this should modify the IRQ's penalty, but it shouldn't depend on
>> the acpi_irq_pci_sharing_penalty() value at all.
>>

Same problem here. This line will be broken after the sci_penalty change.

acpi_isa_irq_penalty[irq] = acpi_irq_get_penalty(irq) +
(active ? PIRQ_PENALTY_ISA_USED : PIRQ_PENALTY_PCI_USING);

--
Sinan Kaya
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.