[alsa-devel] [PATCH 1/5] ACPICA: Add acpi_dev_present

[Rafael J. Wysocki]

On Tuesday, November 24, 2015 12:40:51 PM Hanjun Guo wrote:
> On 2015/11/24 7:32, Lukas Wunner wrote:
> > Hi Robert,
> >
> > On Mon, Nov 23, 2015 at 10:22:27PM +0000, Moore, Robert wrote:
> >>>> acpi_dev_present
> >> Do you really want to be walking the ACPICA namespace for every call?
> > That's what the drivers currently do. Typically this is called only once
> > on initialization by the driver's ->probe callback.
> >
> > What did you have in mind instead, cache the result? Or store the HIDs
> > in the namespace in a hash that can be queried faster?
> 
> Will those drivers be loaded before the acpi namespace is scanned? if not, I think
> those IDs already cached, in acpi_init_device_object(),
> 
> INIT_LIST_HEAD(&device->pnp.ids);
> ...
> acpi_set_pnp_ids(handle, &device->pnp, type);
> 
> please see API acpi_device_hid(), so I think you can introduce a API with
> acpi_device and HID passed as arguments in scan.c

I'd prefer that to go to utils.c to be honest, even if the namespace needs to
be walked.

Thanks,
Rafael