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

[Hanjun Guo]

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

Thanks
Hanjun