From mboxrd@z Thu Jan  1 00:00:00 1970
From: Shaohua Li <shaohua.li@intel.com>
Subject: RE: A reference implementation of PCI suspend/resume?
Date: Mon, 16 May 2005 16:55:34 +0800
Message-ID: <1116233734.7314.7.camel@linux-hp.sh.intel.com>
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To: Fabrice Gautier <Fabrice_Gautier@sdesigns.com>
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On Fri, 2005-05-13 at 22:06 -0700, Fabrice Gautier wrote:
> > There are still many PCI drivers don't implement their 
> > .suspend/.resume
> > methods correctly. I felt it would be quite helpful there is 
> > a reference
> > implementation. Here is my thought:
> > 
> > [...snip...]
> > 
> > Currently many drivers don't call
> > free_irq/request_irq/pci_disable_device, which makes unexpected
> > interrupt occur and even break suspend/resume in some systems. 
> 
> I don't understand why not calling free_irq would cause unexpected
> interrupts.
> 
> The way I understand the PCI spec is: if you suspend a PCI device, its IRQ
> should be disabled. If an IRQ come from this device anyway (in violation of
> the spec) then the driver for this device should handle it so you should NOT
> unregister its irq_handler.
> (How does such a device would handle such a irq is another matter - a device
> specific one I guess)
> 
> I'm not understanding where your unexpected interrupt is coming from.
> 
> Care to elaborate?
I actually don't know the exact reason but we did notice disabling a
device isn't sufficient (an 'irq nobody card' is reported after a device
is disabled). I think we should not trust device.
Another point is resume is just like boot. At boot time, PIC/IOAPIC/irq
router are disabled by default. They are enabled only when a device
really starts using them. suspend/resume should be the same manner.

Thanks,
Shaohua


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