Public > -----Original Message----- > From: Maciej Kucharek <[email protected]> > Sent: Wednesday, October 14, 2026 3:21 PM > To: [email protected]; Deucher, Alexander > <[email protected]> > Cc: Koenig, Christian <[email protected]>; Maciej Kucharek > <[email protected]> > Subject: [PATCH] drm/amdgpu: reset SI ASIC on MacBookPros with VRAM at > 0 > > On MacBookPros with switchable graphics, the firmware puts VRAM at MC > address 0 when the iGPU is enabled. The EFI stub enables the iGPU on these > machines through apple_set_os(). On a MacBookPro11,5 (Radeon R9 > M370X, 1002:6821, subsystem 106b:0149), the driver adopts this layout at > init: > > MC_VM_FB_LOCATION=0x007f0000, HDP_NONSURFACE_BASE=0 > VRAM at 0x0-0x7fffffff, GART table at 0x1400000 > > The driver posts the ASIC again on S3 resume and after a GPU reset. > The VBIOS asic_init table then moves VRAM back to the VBIOS default: > > MC_VM_FB_LOCATION=0xf47ff400, HDP_NONSURFACE_BASE=0xf4000000 > > gmc_v6_0 does not reprogram these registers. The GART table is then no > longer in VRAM, and the gfx ring test times out: > > amdgpu: ring gfx test failed (-110) > amdgpu: resume of IP block <gfx_v6_0> failed -110 > > Reset and post the ASIC at driver load on Apple boards with VRAM at 0. > The driver then uses the VBIOS layout (VRAM at 0xf400000000) from the > start, and later posts keep it. After the reset, FB_BASE is not 0, so a > module > reload does not reset the ASIC again. > > The test is the same one that commit c7f44ec5c4ec ("drm/amdgpu: make Mac > FB workaround generic") uses: an Apple subsystem vendor and VRAM at 0. > The VI quirks for the MacBookPro14,3 and MacBookPro15,1 reset at load for > the same reason: > > commit a22e5e4f2ebb ("drm/amdgpu: reset VI ASIC on MacBookPro14,3") > commit a5be7ad8f5f0 ("drm/amdgpu: reset VI ASIC on MacBookPro15,1") > > Other Apple SI boards only change if their firmware also leaves VRAM at 0. > They then get the same reset at load.
Can you also update the VI code to follow the same logic? Or better yet, add the same logic to si.c, cik.c, and vi.c. Presumably CI based chips have the same issue. Alex > > Tested on a MacBookPro11,5 with 7.2.5 and this patch: the panel comes up at > boot, and 4 of 4 deep S3 cycles resume. Without the patch, S3 resume fails > every time. The GPU reset path is not tested. > > Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/5978 > Cc: [email protected] > Assisted-by: Claude:claude-opus-5-5 > Signed-off-by: Maciej Kucharek <[email protected]> > --- > drivers/gpu/drm/amd/amdgpu/si.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/drivers/gpu/drm/amd/amdgpu/si.c > b/drivers/gpu/drm/amd/amdgpu/si.c index 0adfd4b10..892e80f09 100644 > --- a/drivers/gpu/drm/amd/amdgpu/si.c > +++ b/drivers/gpu/drm/amd/amdgpu/si.c > @@ -1512,6 +1512,15 @@ static void si_invalidate_hdp(struct > amdgpu_device *adev, > > static bool si_need_reset_on_init(struct amdgpu_device *adev) { > + /* > + * MacBookPros with switchable graphics put VRAM at 0. Any later > post > + * (S3 resume, GPU reset) moves it back to the vbios default, so reset > + * and post on load to start with the vbios layout. > + */ > + if (adev->pdev->subsystem_vendor == PCI_VENDOR_ID_APPLE && > + !(RREG32(mmMC_VM_FB_LOCATION) & > MC_VM_FB_LOCATION__FB_BASE_MASK)) > + return true; > + > return false; > } > > -- > 2.55.0
