drm/amdgpu: require _PR3 for BOCO

amdgpu_device_supports_boco() returns true for an AMD_IS_PX device on a
system with a hybrid ATPX method even when the device has no ACPI power
resource (_PR3). On an APU mini PC with a discrete GPU attached over
OCuLink, the iGPU's ATPX method reports hybrid graphics, the dGPU is
flagged AMD_IS_PX, and runtime PM in auto mode picks BOCO:

  amdgpu: ATPX Hybrid Graphics
  amdgpu 0000:c6:00.0: Using BOCO for runtime pm

In BOCO mode the driver leaves powering the device off to the PCI core,
which can only do it through _PR3 on the upstream bridge. No device on
this dGPU's path has _PR3, so when it runtime suspends the card stays
powered, with its fans at about 700 rpm.

Require has_pr3 for BOCO, as the function's description ("dGPU with ACPI
power resources") says. The same card then picks BACO, which powers it
down:

  amdgpu 0000:c6:00.0: Using BACO for runtime pm

This only changes systems with a hybrid ATPX method and no _PR3 on the
dGPU's upstream bridge, where BOCO cannot cut the power today. Tested on
one such system only, an RX 9070 XT (Navi 48) over OCuLink with a Ryzen
AI 9 HX 470, with the change backported to 7.2.9: the stock module logs
"Using BOCO", the patched one "Using BACO"; BACO runtime suspend powers
the card off and it resumes cleanly. Not tested on a hybrid laptop or a
Thunderbolt eGPU.

Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/5980
Assisted-by: Claude:claude-opus-5-5
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Luigi Lauro <luigi.lauro@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 1a039805354a44aab7abb2a6e685212d48b17a5e)
Cc: stable@vger.kernel.org

0 files changed, 0 insertions, 0 deletions