Not entirely sure why this never came up when I originally tested this (maybe some BIOSes already have this setup?) but the ->caps_init vfunc appears to cause the display engine to throw an exception on driver init, at least on my ThinkPad P72:

nouveau 0000:01:00.0: disp: chid 0 mthd 008c data 00000000 0000508c 0000102b

This is magic nvidia speak for "You need to have the DMA notifier offset programmed before you can call NV507D_GET_CAPABILITIES." So, let's fix this by doing that, and also perform an update afterwards to prevent racing with the GPU when reading capabilities.

Changes since v1: * Don't just program the DMA notifier offset, make sure to actually perform an update

Signed-off-by: Lyude Paul lyude@redhat.com Fixes: 4a2cb4181b07 ("drm/nouveau/kms/nv50-: Probe SOR and PIOR caps for DP interlacing support") Cc: stable@vger.kernel.org # v5.8+ --- drivers/gpu/drm/nouveau/dispnv50/core507d.c | 22 +++++++++++++++++++-- 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/dispnv50/core507d.c b/drivers/gpu/drm/nouveau/dispnv50/core507d.c index ad1f09a143aa4..fc4bf9ca59f85 100644 --- a/drivers/gpu/drm/nouveau/dispnv50/core507d.c +++ b/drivers/gpu/drm/nouveau/dispnv50/core507d.c @@ -77,14 +77,32 @@ core507d_ntfy_init(struct nouveau_bo *bo, u32 offset) int core507d_caps_init(struct nouveau_drm *drm, struct nv50_disp *disp) { + struct nv50_core *core = disp->core; struct nvif_push *push = disp->core->chan.push; + u32 interlock[NV50_DISP_INTERLOCK__SIZE] = {0}; int ret;

- if ((ret = PUSH_WAIT(push, 2))) + core->func->ntfy_init(disp->sync, NV50_DISP_CORE_NTFY); + + if ((ret = PUSH_WAIT(push, 4))) return ret;

+ PUSH_MTHD(push, NV507D, SET_NOTIFIER_CONTROL, + NVDEF(NV507D, SET_NOTIFIER_CONTROL, MODE, WRITE) | + NVVAL(NV507D, SET_NOTIFIER_CONTROL, OFFSET, NV50_DISP_CORE_NTFY >> 2) | + NVDEF(NV507D, SET_NOTIFIER_CONTROL, NOTIFY, ENABLE)); PUSH_MTHD(push, NV507D, GET_CAPABILITIES, 0x00000000); - return PUSH_KICK(push); + + ret = PUSH_KICK(push); + if (ret) + return ret; + + core->func->update(core, interlock, false); + if (core->func->ntfy_wait_done(disp->sync, NV50_DISP_CORE_NTFY, + core->chan.base.device)) + NV_ERROR(drm, "core notifier timeout\n"); + + return 0; }

int