[Intel-gfx] [PATCH v8 1/2] ACPI / bus: Introduce a list of ids for "always present" devices

[Andy Shevchenko]

On Fri, 2017-04-21 at 12:47 +0200, Hans de Goede wrote:
> Several Bay / Cherry Trail devices (all of which ship with Windows 10)
> hide
> the LPSS PWM controller in ACPI, typically the _STA method looks like
> this:
> 
>     Method (_STA, 0, NotSerialized)  // _STA: Status
>     {
>         If (OSID == One)
>         {
>             Return (Zero)
>         }
> 
>         Return (0x0F)
>     }
> 
> Where OSID is some dark magic seen in all Cherry Trail ACPI tables
> making
> the machine behave differently depending on which OS it *thinks* it is
> booting, this gets set in a number of ways which we cannot control, on
> some newer machines it simple hardcoded to "One" aka win10.
> 
> This causes the PWM controller to get hidden, which means Linux cannot
> control the backlight level on cht based tablets / laptops.
> 
> Since loading the driver for this does no harm (the only in kernel
> user
> of it is the i915 driver, which will only uses it when it needs it),
> this
> commit makes acpi_bus_get_status() always set status to
> ACPI_STA_DEFAULT
> for the LPSS PWM device, fixing the lack of backlight control.
> 

>  drivers/acpi/Makefile        |  1 +
>  drivers/acpi/bus.c           |  5 +++
>  drivers/acpi/x86/x86_utils.c | 85
> ++++++++++++++++++++++++++++++++++++++++++++

Perhaps .../x86/utils.c ?

>  include/acpi/acpi_bus.h      |  9 +++++

> diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
> index 34fbe02..784bda6 100644
> --- a/drivers/acpi/bus.c
> +++ b/drivers/acpi/bus.c
> @@ -114,6 +114,11 @@ int acpi_bus_get_status(struct acpi_device
> *device)
>  	acpi_status status;
>  	unsigned long long sta;
>  
> +	if (acpi_device_always_present(device)) {
> +		acpi_set_device_status(device, ACPI_STA_DEFAULT);
> +		return 0;
> +	}
> +
>  	status = acpi_bus_get_status_handle(device->handle, &sta);
>  	if (ACPI_FAILURE(status))
>  		return -ENODEV;
> 

> +#define ICPU(model)	{ X86_VENDOR_INTEL, 6, model,
> X86_FEATURE_ANY, }
> +

> +#define ENTRY(hid, uid, cpu_models) {				

cpu_models -> cpu_model ?

Or I missed that it's an array?

-- 
Andy Shevchenko <andriy.shevchenko at linux.intel.com>
Intel Finland Oy