Re: [ACPI] [Proposal]Another way to save/restore PCI config spacefor suspend/resume

[Li Shaohua]

On Wed, 2004-10-27 at 09:32, Hiroshi 2 Itoh wrote:
> 
> 
> Hi,
> 
> acpi-devel-admin@xxxxxxxxxxxxxxxxxxxxx wrote on 2004/10/26 13:50:57:
> 
> > Hi,
> > We suffer from PCI config space issue for a long time, which causes many
> > system can't correctly resume. Current Linux mechanism isn't sufficient.
> > Here is a another idea:
> > Record all PCI writes in Linux kernel, and redo all the write after
> > resume in order. The idea assumes Firmware will restore all PCI config
> > space to the boot time state, which is true at least for IA32.
> >
> 
> I think a basic problem of current Linux device model is that there is no
> effective message path from sibling devices to their root device.
> Although the message direction from a root device to sibling devices is
> natural from the viewpoint of device enumeration, the direction from
> sibling devices to a root device is required for effective arbitration for
> device configuration and power management.
> 
> The Windows driver model uses the direction from sibling drivers to a root
> bus driver mainly, i.e. sibling drivers are layered on a root bus driver.
> While we need a kind of callback mechanism from PCI (sibling) devices to
> PCI bus (root) device instead because their normal call interface is from a
> root device to sibling devices.
Hiro-san,
I don't really understand why this is related with suspend/resume. Could
you please explain it more clearly?

Thanks,
Shaohua


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