Nouveau - May 2023 - [PATCH] drm/nouveau: bring back blit subchannel for pre nv50 GPUs

1ba6113a90a0 removed a lot of the kernel GPU channel, but method 0x128
was important as otherwise the GPU spams us with `CACHE_ERROR` messages.

We use the blit subchannel inside our vblank handling, so we should keep
at least this part.

Closes: https://gitlab.freedesktop.org/drm/nouveau/-/issues/201
Fixes: 4a16dd9d18a0 ("drm/nouveau/kms: switch to drm fbdev helpers")
Signed-off-by: Karol Herbst <kherbst at redhat.com>
---
 drivers/gpu/drm/nouveau/nouveau_chan.c |  1 +
 drivers/gpu/drm/nouveau/nouveau_chan.h |  1 +
 drivers/gpu/drm/nouveau/nouveau_drm.c  | 19 ++++++++++++++++---
 3 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_chan.c
b/drivers/gpu/drm/nouveau/nouveau_chan.c
index e648ecd0c1a0..3dfbc374478e 100644
--- a/drivers/gpu/drm/nouveau/nouveau_chan.c
+++ b/drivers/gpu/drm/nouveau/nouveau_chan.c
@@ -90,6 +90,7 @@ nouveau_channel_del(struct nouveau_channel **pchan)
 		if (cli)
 			nouveau_svmm_part(chan->vmm->svmm, chan->inst);
 
+		nvif_object_dtor(&chan->blit);
 		nvif_object_dtor(&chan->nvsw);
 		nvif_object_dtor(&chan->gart);
 		nvif_object_dtor(&chan->vram);
diff --git a/drivers/gpu/drm/nouveau/nouveau_chan.h
b/drivers/gpu/drm/nouveau/nouveau_chan.h
index e06a8ffed31a..bad7466bd0d5 100644
--- a/drivers/gpu/drm/nouveau/nouveau_chan.h
+++ b/drivers/gpu/drm/nouveau/nouveau_chan.h
@@ -53,6 +53,7 @@ struct nouveau_channel {
 	u32 user_put;
 
 	struct nvif_object user;
+	struct nvif_object blit;
 
 	struct nvif_event kill;
 	atomic_t killed;
diff --git a/drivers/gpu/drm/nouveau/nouveau_drm.c
b/drivers/gpu/drm/nouveau/nouveau_drm.c
index cc7c5b4a05fd..59e040a93a41 100644
--- a/drivers/gpu/drm/nouveau/nouveau_drm.c
+++ b/drivers/gpu/drm/nouveau/nouveau_drm.c
@@ -369,15 +369,28 @@ nouveau_accel_gr_init(struct nouveau_drm *drm)
 		ret = nvif_object_ctor(&drm->channel->user, "drmNvsw",
 				       NVDRM_NVSW, nouveau_abi16_swclass(drm),
 				       NULL, 0, &drm->channel->nvsw);
+
+		if (ret == 0) {
+			u32 blit_class = device->info.chipset >= 0x11 ? 0x009f : 0x005f;
+			ret = nvif_object_ctor(&drm->channel->user, "drmBlit",
+					       0x005f, blit_class,
+					       NULL, 0, &drm->channel->blit);
+		}
+
 		if (ret == 0) {
 			struct nvif_push *push = drm->channel->chan.push;
-			ret = PUSH_WAIT(push, 2);
-			if (ret == 0)
+			ret = PUSH_WAIT(push, 8);
+			if (ret == 0) {
+				PUSH_NVSQ(push, NV05F, 0x0000, drm->channel->blit.handle);
+				PUSH_NVSQ(push, NV09F, 0x0120, 0,
+						       0x0124, 1,
+						       0x0128, 2);
 				PUSH_NVSQ(push, NV_SW, 0x0000, drm->channel->nvsw.handle);
+			}
 		}
 
 		if (ret) {
-			NV_ERROR(drm, "failed to allocate sw class, %d\n", ret);
+			NV_ERROR(drm, "failed to allocate sw or blit class, %d\n", ret);
 			nouveau_accel_gr_fini(drm);
 			return;
 		}
-- 
2.40.1