-----Original Message----- From: Hanjun Guo [mailto:[email protected]] Sent: Monday, November 23, 2015 8:41 PM To: Lukas Wunner; Moore, Robert Cc: Rafael J. Wysocki; linux-acpi(a)vger.kernel.org; devel(a)acpica.org; platform-driver-x86(a)vger.kernel.org; Darren Hart; Corentin Chary; Lee, Chun-Yi; alsa-devel(a)alsa-project.org; Takashi Iwai; Hui Wang; Mark Brown; Zheng, Lv; David Box Subject: Re: [PATCH 1/5] ACPICA: Add acpi_dev_present 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