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

4 files changed, 94 insertions, 13 deletions

diff --git a/drivers/gpu/drm/nouveau/nvkm/engine/disp/dp.c b/drivers/gpu/drm/nouveau/nvkm/engine/disp/dp.c
index 0d2de4769b94..3b6d58c15452 100644
--- a/drivers/gpu/drm/nouveau/nvkm/engine/disp/dp.c
+++ b/drivers/gpu/drm/nouveau/nvkm/engine/disp/dp.c
@@ -808,6 +808,7 @@ nvkm_dp_func = {
 	.init = nvkm_dp_init,
 	.fini = nvkm_dp_fini,
 	.detect = nvkm_outp_detect,
+	.inherit = nvkm_outp_inherit,
 	.acquire = nvkm_dp_acquire,
 	.release = nvkm_dp_release,
 	.disable = nvkm_dp_disable,
diff --git a/drivers/gpu/drm/nouveau/nvkm/engine/disp/outp.c b/drivers/gpu/drm/nouveau/nvkm/engine/disp/outp.c
index 3ed93df475fc..5b55598e09c8 100644
--- a/drivers/gpu/drm/nouveau/nvkm/engine/disp/outp.c
+++ b/drivers/gpu/drm/nouveau/nvkm/engine/disp/outp.c
@@ -104,7 +104,7 @@ nvkm_outp_release_or(struct nvkm_outp *outp, u8 user)
 	}
 }
 
-static inline int
+int
 nvkm_outp_acquire_ior(struct nvkm_outp *outp, u8 user, struct nvkm_ior *ior)
 {
 	outp->ior = ior;
@@ -247,32 +247,30 @@ nvkm_outp_fini(struct nvkm_outp *outp)
 		outp->func->fini(outp);
 }
 
-static void
-nvkm_outp_init_route(struct nvkm_outp *outp)
+struct nvkm_ior *
+nvkm_outp_inherit(struct nvkm_outp *outp)
 {
 	struct nvkm_disp *disp = outp->disp;
+	struct nvkm_ior *ior;
 	enum nvkm_ior_proto proto;
 	enum nvkm_ior_type type;
-	struct nvkm_ior *ior;
 	int id, link;
 
 	/* Find any OR from the class that is able to support this device. */
 	proto = nvkm_outp_xlat(outp, &type);
 	if (proto == UNKNOWN)
-		return;
+		return NULL;
 
 	ior = nvkm_ior_find(disp, type, -1);
-	if (!ior) {
-		WARN_ON(1);
-		return;
-	}
+	if (WARN_ON(!ior))
+		return NULL;
 
 	/* Determine the specific OR, if any, this device is attached to. */
 	if (ior->func->route.get) {
 		id = ior->func->route.get(outp, &link);
 		if (id < 0) {
 			OUTP_DBG(outp, "no route");
-			return;
+			return NULL;
 		}
 	} else {
 		/* Prior to DCB 4.1, this is hardwired like so. */
@@ -281,10 +279,24 @@ nvkm_outp_init_route(struct nvkm_outp *outp)
 	}
 
 	ior = nvkm_ior_find(disp, type, id);
-	if (!ior) {
-		WARN_ON(1);
+	if (WARN_ON(!ior))
+		return NULL;
+
+	return ior;
+}
+
+static void
+nvkm_outp_init_route(struct nvkm_outp *outp)
+{
+	enum nvkm_ior_proto proto;
+	enum nvkm_ior_type type;
+	struct nvkm_ior *ior;
+
+	/* Find any OR from the class that is able to support this device. */
+	proto = nvkm_outp_xlat(outp, &type);
+	ior = outp->func->inherit(outp);
+	if (!ior)
 		return;
-	}
 
 	/* Determine if the OR is already configured for this device. */
 	ior->func->state(ior, &ior->arm);
@@ -362,6 +374,7 @@ nvkm_outp_new_(const struct nvkm_outp_func *func, struct nvkm_disp *disp,
 static const struct nvkm_outp_func
 nvkm_outp = {
 	.detect = nvkm_outp_detect,
+	.inherit = nvkm_outp_inherit,
 };
 
 int
diff --git a/drivers/gpu/drm/nouveau/nvkm/engine/disp/outp.h b/drivers/gpu/drm/nouveau/nvkm/engine/disp/outp.h
index 76d83fb9c6e5..ab1699b07acc 100644
--- a/drivers/gpu/drm/nouveau/nvkm/engine/disp/outp.h
+++ b/drivers/gpu/drm/nouveau/nvkm/engine/disp/outp.h
@@ -77,7 +77,9 @@ void nvkm_outp_fini(struct nvkm_outp *);
 
 int nvkm_outp_detect(struct nvkm_outp *);
 
+struct nvkm_ior *nvkm_outp_inherit(struct nvkm_outp *);
 int nvkm_outp_acquire_or(struct nvkm_outp *, u8 user, bool hda);
+int nvkm_outp_acquire_ior(struct nvkm_outp *, u8 user, struct nvkm_ior *);
 void nvkm_outp_release(struct nvkm_outp *);
 void nvkm_outp_release_or(struct nvkm_outp *, u8 user);
 void nvkm_outp_route(struct nvkm_disp *);
@@ -90,6 +92,7 @@ struct nvkm_outp_func {
 	int (*detect)(struct nvkm_outp *);
 	int (*edid_get)(struct nvkm_outp *, u8 *data, u16 *size);
 
+	struct nvkm_ior *(*inherit)(struct nvkm_outp *);
 	int (*acquire)(struct nvkm_outp *);
 	void (*release)(struct nvkm_outp *);
 	void (*disable)(struct nvkm_outp *, struct nvkm_ior *);
diff --git a/drivers/gpu/drm/nouveau/nvkm/engine/disp/uoutp.c b/drivers/gpu/drm/nouveau/nvkm/engine/disp/uoutp.c
index 828db77af242..31b76f17fa70 100644
--- a/drivers/gpu/drm/nouveau/nvkm/engine/disp/uoutp.c
+++ b/drivers/gpu/drm/nouveau/nvkm/engine/disp/uoutp.c
@@ -253,6 +253,69 @@ nvkm_uoutp_mthd_acquire(struct nvkm_outp *outp, void *argv, u32 argc)
 }
 
 static int
+nvkm_uoutp_mthd_inherit(struct nvkm_outp *outp, void *argv, u32 argc)
+{
+	union nvif_outp_inherit_args *args = argv;
+	struct nvkm_ior *ior;
+	int ret = 0;
+
+	if (argc != sizeof(args->v0) || args->v0.version != 0)
+		return -ENOSYS;
+
+	/* Ensure an ior is hooked up to this outp already */
+	ior = outp->func->inherit(outp);
+	if (!ior)
+		return -ENODEV;
+
+	/* With iors, there will be a separate output path for each type of connector - and all of
+	 * them will appear to be hooked up. Figure out which one is actually the one we're using
+	 * based on the protocol we were given over nvif
+	 */
+	switch (args->v0.proto) {
+	case NVIF_OUTP_INHERIT_V0_TMDS:
+		if (ior->arm.proto != TMDS)
+			return -ENODEV;
+		break;
+	case NVIF_OUTP_INHERIT_V0_DP:
+		if (ior->arm.proto != DP)
+			return -ENODEV;
+		break;
+	case NVIF_OUTP_INHERIT_V0_LVDS:
+		if (ior->arm.proto != LVDS)
+			return -ENODEV;
+		break;
+	case NVIF_OUTP_INHERIT_V0_TV:
+		if (ior->arm.proto != TV)
+			return -ENODEV;
+		break;
+	case NVIF_OUTP_INHERIT_V0_RGB_CRT:
+		if (ior->arm.proto != CRT)
+			return -ENODEV;
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+	/* Make sure that userspace hasn't already acquired this */
+	if (outp->acquired) {
+		OUTP_ERR(outp, "cannot inherit an already acquired (%02x) outp", outp->acquired);
+		return -EBUSY;
+	}
+
+	/* Mark the outp acquired by userspace now that we've confirmed it's already active */
+	OUTP_TRACE(outp, "inherit %02x |= %02x %p", outp->acquired, NVKM_OUTP_USER, ior);
+	nvkm_outp_acquire_ior(outp, NVKM_OUTP_USER, ior);
+
+	args->v0.or = ior->id;
+	args->v0.link = ior->arm.link;
+	args->v0.head = ffs(ior->arm.head) - 1;
+	args->v0.proto = ior->arm.proto_evo;
+
+	return ret;
+}
+
+static int
 nvkm_uoutp_mthd_load_detect(struct nvkm_outp *outp, void *argv, u32 argc)
 {
 	union nvif_outp_load_detect_args *args = argv;
@@ -334,6 +397,7 @@ nvkm_uoutp_mthd_noacquire(struct nvkm_outp *outp, u32 mthd, void *argv, u32 argc
 	switch (mthd) {
 	case NVIF_OUTP_V0_DETECT     : return nvkm_uoutp_mthd_detect     (outp, argv, argc);
 	case NVIF_OUTP_V0_EDID_GET   : return nvkm_uoutp_mthd_edid_get   (outp, argv, argc);
+	case NVIF_OUTP_V0_INHERIT    : return nvkm_uoutp_mthd_inherit    (outp, argv, argc);
 	case NVIF_OUTP_V0_ACQUIRE    : return nvkm_uoutp_mthd_acquire    (outp, argv, argc);
 	case NVIF_OUTP_V0_LOAD_DETECT: return nvkm_uoutp_mthd_load_detect(outp, argv, argc);
 	case NVIF_OUTP_V0_DP_AUX_PWR : return nvkm_uoutp_mthd_dp_aux_pwr (outp, argv, argc);