Re: [PATCH] pci: do not try to assign irq 255

From: Yinghai Lu
Date: Wed Feb 20 2013 - 11:57:36 EST

On Tue, Feb 19, 2013 at 11:58 PM, Hannes Reinecke <hare@xxxxxxx> wrote:
> Apparently this device is meant to use MSI _only_ so the BIOS developer
> didn't feel the need to assign an INTx here.
> According to PCI-3.0, section 6.8 (Message Signalled Interrupts):
>> It is recommended that devices implement interrupt pins to
>> provide compatibility in systems that do not support MSI
>> (devices default to interrupt pins). However, it is expected
>> that the need for interrupt pins will diminish over time.
>> Devices that do not support interrupt pins due to pin
>> constraints (rely on polling for device service) may implement
>> messages to increase performance without adding additional pins. >
>> Therefore, system configuration software must not assume that a
>> message capable device has an interrupt pin.
> Which sounds to me as if the implementation is valid...

it seems you mess pin with interrupt line.

current code:
unsigned char irq;

pci_read_config_byte(dev, PCI_INTERRUPT_PIN, &irq);
dev->pin = irq;
if (irq)
pci_read_config_byte(dev, PCI_INTERRUPT_LINE, &irq);
dev->irq = irq;

so if the device does not have interrupt pin implemented, pin should be zero.
and pin and irq in dev should
be all 0.


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