On Wednesday, August 31, 2005 2:44 PM Greg KH wrote:
>>On Thu, Aug 18, 2005 at 01:35:46PM +0800, Shaohua Li wrote:
>> Hi,
>> It appears pci_enable_msi doesn't reconfigure msi registers if it
>> successfully look up a msi for a device. It assumes the data and
address
>> registers unchanged after calling pci_disable_msi. But this isn't
always
>> true, such as in a suspend/resume circle. In my test system, the
>> registers unsurprised become zero after a S3 resume. This patch fixes
my
>> problem, please look at it. MSIX might have the same issue, but I
>> haven't taken a close look.
> Tom, any comments on this?
In the cases of suspend/resume, a device driver needs to restore its PCI
configuration space registers, which include the MSI/MSI-X capability
structures if a device uses MSI/MSI-X. I think reconfiguring MSI
data/address each time a driver calls pci_enable_msi may not be
necessary.
Thanks,
Tom
"Nguyen, Tom L" <[email protected]> wrote:
>
> On Wednesday, August 31, 2005 2:44 PM Greg KH wrote:
> >>On Thu, Aug 18, 2005 at 01:35:46PM +0800, Shaohua Li wrote:
> >> Hi,
> >> It appears pci_enable_msi doesn't reconfigure msi registers if it
> >> successfully look up a msi for a device. It assumes the data and
> address
> >> registers unchanged after calling pci_disable_msi. But this isn't
> always
> >> true, such as in a suspend/resume circle. In my test system, the
> >> registers unsurprised become zero after a S3 resume. This patch fixes
> my
> >> problem, please look at it. MSIX might have the same issue, but I
> >> haven't taken a close look.
>
> > Tom, any comments on this?
>
> In the cases of suspend/resume, a device driver needs to restore its PCI
> configuration space registers, which include the MSI/MSI-X capability
> structures if a device uses MSI/MSI-X. I think reconfiguring MSI
> data/address each time a driver calls pci_enable_msi may not be
> necessary.
>
So what is the alternative to Shaohua's fix? Restore all the msi registers
on resume?
On Thu, 2005-09-01 at 23:20 +0800, Nguyen, Tom L wrote:
> On Wednesday, August 31, 2005 2:44 PM Greg KH wrote:
> >>On Thu, Aug 18, 2005 at 01:35:46PM +0800, Shaohua Li wrote:
> >> Hi,
> >> It appears pci_enable_msi doesn't reconfigure msi registers if it
> >> successfully look up a msi for a device. It assumes the data and
> address
> >> registers unchanged after calling pci_disable_msi. But this isn't
> always
> >> true, such as in a suspend/resume circle. In my test system, the
> >> registers unsurprised become zero after a S3 resume. This patch fixes
> my
> >> problem, please look at it. MSIX might have the same issue, but I
> >> haven't taken a close look.
>
> > Tom, any comments on this?
>
> In the cases of suspend/resume, a device driver needs to restore its PCI
> configuration space registers, which include the MSI/MSI-X capability
> structures if a device uses MSI/MSI-X. I think reconfiguring MSI
> data/address each time a driver calls pci_enable_msi may not be
> necessary.
Just when you called pci_disable_msi, reconfiguring MSI registers should
be done. Is there any pain of reconfiguring MSI registers?
I don't understand why should we have the assumption. If you disabled
the ability, you must reconfigure it to me. This is the easy logic.
Thanks,
Shaohua