[PATCH 0/3] platform/x86: asus-armoury: Add dgpu_power_state and check in dgpu_disable

[Marco Scardovi <scardracs@disroot.org>]

This patch series adds support for WMI device ID 0x00120097
(ASUS_WMI_DEVID_DGPU_POWER_STATE) to query the power state level of the
discrete GPU (dGPU) on ASUS ROG laptops, and uses it to prevent disabling
the dGPU while it is in active use.

--- Background & How it Works ---

Modern ASUS ROG firmware provides WMI device ID 0x00120097 in the ACPI DSTS
evaluation method:

If ((IIA0 == 0x00120097))
{
  Return (0x00010000)
}

When queried, DSTS returns:
  - Bit 16 (0x00010000): Presence bit (set when supported by ACPI).
  - Bit 0  (0x00000001): Power state status:
      * 0: D3 cold (off / suspended)
      * 1: D0 (active / powered on)

--- Patch Series Summary ---

- Patch 1/3: Defines ASUS_WMI_DEVID_DGPU_POWER_STATE (0x00120097) in
  include/linux/platform_data/x86/asus-wmi.h.
- Patch 2/3: Registers the read-only sysfs attribute 'dgpu_power_state' in
  drivers/platform/x86/asus-armoury.c under firmware_attributes class.
- Patch 3/3: Consolidates dgpu_disable checks under a single 'if (disable)'
  block and returns -EBUSY if an attempt is made to disable the dGPU while active.

--- Testing ---

Verified on ASUS ROG G614PR hardware:
- Reading 'current_value' returns 0 when the dGPU is suspended in D3 cold,
  and 1 when active in D0.
- Attempting to disable the dGPU while in use returns -EBUSY.

Suggested-by: Denis Benato <denis.benato@linux.dev>
Signed-off-by: Marco Scardovi <scardracs@disroot.org>

Marco Scardovi (3):
  platform/x86: asus-wmi: Add ASUS_WMI_DEVID_DGPU_POWER_STATE define
  platform/x86: asus-armoury: Add dgpu_power_state attribute
  platform/x86: asus-armoury: Prevent disabling dGPU when in use

 drivers/platform/x86/asus-armoury.c        | 29 ++++++++++++++++------
 include/linux/platform_data/x86/asus-wmi.h |  3 ++-
 2 files changed, 24 insertions(+), 8 deletions(-)

-- 
2.55.0