drm/nouveau/kms: Add INHERIT ioctl to nvkm/nvif for reading IOR state

Now that we're supporting things like Ada and the GSP, there's situations
where we really need to actually know the display state that we're starting
with when loading the driver in order to prevent breaking GSP expectations.
The first step in doing this is making it so that we can read the current
state of IORs from nvkm in DRM, so that we can fill in said into into the
atomic state.

We do this by introducing an INHERIT ioctl to nvkm/nvif. This is basically
another form of ACQUIRE, except that it will only acquire the given output
path for userspace if it's already set up in hardware. This way, we can go
through and probe each outp object we have in DRM in order to figure out
the current hardware state of each one. If the outp isn't in use, it simply
returns -ENODEV.

This is also part of the work that will be required for implementing GSP
support for display. While the GSP should mostly work without this commit,
this commit should fix some edge case bugs that can occur on initial driver
load. This also paves the way for some of the initial groundwork for
fastboot support.

Signed-off-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Acked-by: Danilo Krummrich <me@dakr.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230919220442.202488-11-lyude@redhat.com

1 files changed, 101 insertions, 0 deletions

diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c b/drivers/gpu/drm/nouveau/dispnv50/disp.c
index 889ff667d029..290f3c80ba4e 100644
--- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
+++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
@@ -2519,6 +2519,104 @@ nv50_display_fini(struct drm_device *dev, bool runtime, bool suspend)
 		cancel_work_sync(&drm->hpd_work);
 }
 
+static inline void
+nv50_display_read_hw_or_state(struct drm_device *dev, struct nv50_disp *disp,
+			      struct nouveau_encoder *outp)
+{
+	struct drm_crtc *crtc;
+	struct drm_connector_list_iter conn_iter;
+	struct drm_connector *conn;
+	struct nv50_head_atom *armh;
+	const u32 encoder_mask = drm_encoder_mask(&outp->base.base);
+	bool found_conn = false, found_head = false;
+	u8 proto;
+	int head_idx;
+	int ret;
+
+	switch (outp->dcb->type) {
+	case DCB_OUTPUT_TMDS:
+		ret = nvif_outp_inherit_tmds(&outp->outp, &proto);
+		break;
+	case DCB_OUTPUT_DP:
+		ret = nvif_outp_inherit_dp(&outp->outp, &proto);
+		break;
+	case DCB_OUTPUT_LVDS:
+		ret = nvif_outp_inherit_lvds(&outp->outp, &proto);
+		break;
+	case DCB_OUTPUT_ANALOG:
+		ret = nvif_outp_inherit_rgb_crt(&outp->outp, &proto);
+		break;
+	default:
+		drm_dbg_kms(dev, "Readback for %s not implemented yet, skipping\n",
+			    outp->base.base.name);
+		drm_WARN_ON(dev, true);
+		return;
+	}
+
+	if (ret < 0)
+		return;
+
+	head_idx = ret;
+
+	drm_for_each_crtc(crtc, dev) {
+		if (crtc->index != head_idx)
+			continue;
+
+		armh = nv50_head_atom(crtc->state);
+		found_head = true;
+		break;
+	}
+	if (drm_WARN_ON(dev, !found_head))
+		return;
+
+	/* Figure out which connector is being used by this encoder */
+	drm_connector_list_iter_begin(dev, &conn_iter);
+	nouveau_for_each_non_mst_connector_iter(conn, &conn_iter) {
+		if (nouveau_connector(conn)->index == outp->dcb->connector) {
+			found_conn = true;
+			break;
+		}
+	}
+	drm_connector_list_iter_end(&conn_iter);
+	if (drm_WARN_ON(dev, !found_conn))
+		return;
+
+	armh->state.encoder_mask = encoder_mask;
+	armh->state.connector_mask = drm_connector_mask(conn);
+	armh->state.active = true;
+	armh->state.enable = true;
+	pm_runtime_get_noresume(dev->dev);
+
+	outp->crtc = crtc;
+	outp->ctrl = NVVAL(NV507D, SOR_SET_CONTROL, PROTOCOL, proto) | BIT(crtc->index);
+
+	drm_connector_get(conn);
+	conn->state->crtc = crtc;
+	conn->state->best_encoder = &outp->base.base;
+}
+
+/* Read back the currently programmed display state */
+static void
+nv50_display_read_hw_state(struct nouveau_drm *drm)
+{
+	struct drm_device *dev = drm->dev;
+	struct drm_encoder *encoder;
+	struct drm_modeset_acquire_ctx ctx;
+	struct nv50_disp *disp = nv50_disp(dev);
+	int ret;
+
+	DRM_MODESET_LOCK_ALL_BEGIN(dev, ctx, 0, ret);
+
+	drm_for_each_encoder(encoder, dev) {
+		if (encoder->encoder_type == DRM_MODE_ENCODER_DPMST)
+			continue;
+
+		nv50_display_read_hw_or_state(dev, disp, nouveau_encoder(encoder));
+	}
+
+	DRM_MODESET_LOCK_ALL_END(dev, ctx, ret);
+}
+
 static int
 nv50_display_init(struct drm_device *dev, bool resume, bool runtime)
 {
@@ -2536,6 +2634,9 @@ nv50_display_init(struct drm_device *dev, bool resume, bool runtime)
 		}
 	}
 
+	if (!resume)
+		nv50_display_read_hw_state(nouveau_drm(dev));
+
 	return 0;
 }