Hi Hanjun Guo, thank you for taking a look at the patches. On Mon, Nov 30, 2015 at 04:27:23PM +0800, Hanjun Guo wrote: Of the 7 users, * 4 detect the presence of a particular HID to activate platform- specific quirks (acer-wmi.c, eeepc-wmi.c, thinkpad_helper.c, cht_bsw_max98090_ti.c). The drivers never obtain a pointer to the struct acpi_device. This is also the reason why I need to detect the presence of apple-gmux in several DRM drivers, to activate quirks specific to MacBook Pros with dual GPUs, and the one thing they have in common is the presence of the gmux controller. The DRM drivers likewise never have a need to hold a pointer to apple-gmux' struct acpi_device. * 2 detect the presence of a particular HID and *afterwards* instantiate a platform_device (atom/sst/sst_acpi.c and common/sst-acpi.c). So we can't use acpi_match_device_ids() there either. * 1 is a driver for a platform_device (cht_bsw_rt5645.c) which was instantiated by atom/sst/sst_acpi.c. The driver is responsible for two chips and differentiates between the two by detecting the presence of a particular HID. It would be possible to refactor the code so that atom/sst/sst_acpi.c passes down the matched HID to cht_bsw_rt5645.c, then it wouldn't be necessary to match for a second time. Also, the only difference between the two chipsets seems to be a minute change in struct snd_soc_dapm_route, so I'm wondering if it's necessary to differentiate between the chipsets at all. Mark Brown may want to poke the developers of the driver to refactor the code. TL;DR: 6 of the 7 users can't use acpi_match_device_ids() and the 7th could be refactored so that it doesn't have to detect the presence of a specific HID at all. Best regards, Lukas