Re: [PATCH 0/4]Bind physical devices with ACPI devices - take 2

Li Shaohua
2005-01-06T07:50:34Z

On Thu, 2005-01-06 at 12:00, Len Brown wrote:
> I think we'll save some significant power when ACPI D-states
> are invoked for the devices that supply them. While many
> PCI devices support PCI power management and thus don't need/use
> ACPI D-states, I think it will be even more important to add
> this functionality to the legacy devices which never have
> PCI power management and thus always depend on ACPI for D-states.
It's easy to link the PNP devices with the ACPI devices with the ACPIPNP
driver. But the PNP driver core hasn't similar routines as
'pnp_set_power_state'. Unclear if the PNP drivers support
suspend/resume.

> It looks like some device drivers scribble on dev->platform_data;
> and we need to fix those drivers before deploying this patch.
> Alternatively, we could add a new field to struct device,
> but then we'd probably never get rid of it...
Yep, this is a big problem. According to the comments in the source
file, it's designed for firmware such as ACPI, but some drivers misused
it. A search shows there are many such drivers. Fixing the drivers is a
pain for me.

> I'm a little unformforable with platform_notify
> and platform_notify_remove available as globals.
> We should probably BUG_ON if we
> find them set before ACPI writes on them.
I will fix it.

> We'll need to update this patch to handle erroneous
> but real platforms that don't have _BBN
> by using _CRS to get PCI bus number.
That's ok.

> Unclear to me if/how this association of ACPI capability
> should be reflected in the sysfs device tree.
Possibly both the physical devices and ACPI devices have a link in sysfs
to pointer partners.

Thanks,
Shaohua

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