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Subject: Re: dmesg: PCI interrupts are no longer routed
	automatically.........
From: Bjorn Helgaas <bjorn.helgaas@hp.com>
To: linux-os@analogic.com
Cc: David Vrabel <dvrabel@cantab.net>, aryix <aryix@softhome.net>,
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Date: Wed, 05 Jan 2005 10:13:56 -0700
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On Wed, 2005-01-05 at 07:06 -0500, linux-os wrote:
> The temporary work-around is....
>  	pci_enable_device(pdev);
>  	save_irq = pdev->irq;
>  	pci_disable_device(pdev);	// Turn back off.
> 
>  	init_bars(....);
>  	request_irq(save_irq,...)	// Put ISR in place
> 
>  	pci_write_config_byte(pdev, PCI_CACHE_LINE_SIZE, 0x08);
>  	pci_write_config_byte(pdev, PCI_LATENCY_TIMER, 0x40);
>  	pci_set_dma_mask(pdev, 0x00000000ffffffffULL);
>  	pci_set_drvdata(pdev, NULL);
>  	pci_set_power_state(pdev, 0);
>  	pci_set_master(pdev);
>  	pci_set_mwi(pdev);
>  	pci_write_config_dword(pdev, PCI_COMMAND, PCI_CONFIG);
> 
>  	.... configure chip-specific stuff, clear interrupts, etc.
>  	pci_enable_device(dev);

So prior to 2.6.10, you did something like this?

	request_irq(pdev->irq, ...);
	pci_write_config_byte(pdev, PCI_CACHE_LINE_SIZE, 0x08);
	pci_write_config_byte(pdev, PCI_LATENCY_TIMER, 0x40);
	...
	pci_enable_device(pdev);

What sort of interrupts does the device generate before it's
enabled?  I can't find anything in the PCI spec that actually
prohibits interrupts before the driver starts up the device,
but it does seem strange.

You wouldn't want your ISR mucking around with a half-initialized
device, so does it have to check a "device_configured" flag
or something?