[PATCH v2] drm/amdgpu: reset VI ASIC on MacBookPro14,3

["Francisco Beltrán Millalén" <fbeltranmillalen@gmail.com>]

On a MacBookPro14,3 with a Radeon Pro 555 (Polaris11), the framebuffer
is at MC address 0 when amdgpu loads after a cold boot, as the firmware
leaves it (MC_VM_FB_LOCATION = 0x007f0000), while the VBIOS ASIC_Init
table places it at 0xF4_0000_0000 (0xf47ff400).  amdgpu reads the
location once, at init, so after a re-POST (S3 resume or GPU reset)
the framebuffer has moved and the driver keeps programming the old
one: the SMU is handed a table that was never written and the GPU
does not come back, which leaves the internal panel black.

Resetting the ASIC on load makes ASIC_Init run before the driver reads
the location, so the driver uses the VBIOS placement from the start and
every later re-POST puts the framebuffer back where it already is.

Add the Radeon Pro 555 used in this machine to the existing VI reset
quirk table.

Tested on a MacBookPro14,3 on 6.18.49 with the quirk table backported
(the kernel also carries unrelated local PCI and ACPI patches for this
machine).  The framebuffer is at 0x000000F400000000 after both cold and
warm boot, and the GPU survived 9 S3 cycles (lid close and rtcwake, one
of them with the lid closed for about 7.5 minutes and a USB-C disk
attached), each followed by a few minutes of 3D load; no ring timeouts
or VM faults were reported.  The reset adds about 0.23 s to amdgpu init.

Suggested-by: Christian König <christian.koenig@amd.com>
Suggested-by: Alex Deucher <alexander.deucher@amd.com>
Link: https://lore.kernel.org/all/20260924132952.25054-1-fbeltranmillalen@gmail.com/
Assisted-by: Claude:claude-opus-5-5
Signed-off-by: Francisco Beltrán Millalén <fbeltranmillalen@gmail.com>
---
v2: new approach, as suggested by Christian and Alex: instead of
    rewriting MC_VM_FB_LOCATION after every re-POST in gmc_v8_0
    (v1, withdrawn), reset the ASIC on load through the existing
    vi_reset_quirks table.
v1: https://lore.kernel.org/all/20260924132952.25054-1-fbeltranmillalen@gmail.com/

 drivers/gpu/drm/amd/amdgpu/vi.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/vi.c b/drivers/gpu/drm/amd/amdgpu/vi.c
index 2cd6d7d77..a0435fd55 100644
--- a/drivers/gpu/drm/amd/amdgpu/vi.c
+++ b/drivers/gpu/drm/amd/amdgpu/vi.c
@@ -1397,6 +1397,7 @@ struct vi_reset_quirk {
 static const struct vi_reset_quirk vi_reset_quirks[] = {
 	{ 0x67ef, PCI_VENDOR_ID_APPLE, 0x0190, 0xe3 }, /* Radeon Pro 555X */
 	{ 0x67ef, PCI_VENDOR_ID_APPLE, 0x018f, 0xc2 }, /* Radeon Pro 560X */
+	{ 0x67ef, PCI_VENDOR_ID_APPLE, 0x017a, 0xc7 }, /* Radeon Pro 555 */
 };
 
 static bool vi_need_reset_on_init(struct amdgpu_device *adev)
-- 
2.55.0