drm/nouveau/devinit: fixup various issues with subdev ctor/init ordering

Details of the problem, and solution, are in comments in the commit
proper.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

2 files changed, 38 insertions, 16 deletions

diff --git a/drivers/gpu/drm/nouveau/core/include/core/device.h b/drivers/gpu/drm/nouveau/core/include/core/device.h
index 57899fc3b87..e58b6f0984c 100644
--- a/drivers/gpu/drm/nouveau/core/include/core/device.h
+++ b/drivers/gpu/drm/nouveau/core/include/core/device.h
@@ -8,11 +8,23 @@
 enum nv_subdev_type {
         NVDEV_SUBDEV_DEVICE,
         NVDEV_SUBDEV_VBIOS,
+
+        /* All subdevs from DEVINIT to DEVINIT_LAST will be created before
+         * *any* of them are initialised.  This subdev category is used
+         * for any subdevs that the VBIOS init table parsing may call out
+         * to during POST.
+         */
+        NVDEV_SUBDEV_DEVINIT,
         NVDEV_SUBDEV_GPIO,
         NVDEV_SUBDEV_I2C,
         NVDEV_SUBDEV_CLOCK,
+        NVDEV_SUBDEV_DEVINIT_LAST = NVDEV_SUBDEV_CLOCK,
+
+        /* This grouping of subdevs are initialised right after they've
+         * been created, and are allowed to assume any subdevs in the
+         * list above them exist and have been initialised.
+         */
         NVDEV_SUBDEV_MXM,
-        NVDEV_SUBDEV_DEVINIT,
         NVDEV_SUBDEV_MC,
         NVDEV_SUBDEV_TIMER,
         NVDEV_SUBDEV_FB,
@@ -23,6 +35,7 @@ enum nv_subdev_type {
         NVDEV_SUBDEV_BAR,
         NVDEV_SUBDEV_VOLT,
         NVDEV_SUBDEV_THERM,
+
         NVDEV_ENGINE_DMAOBJ,
         NVDEV_ENGINE_FIFO,
         NVDEV_ENGINE_SW,
@@ -38,6 +51,7 @@ enum nv_subdev_type {
         NVDEV_ENGINE_UNK1C1,
         NVDEV_ENGINE_VENC,
         NVDEV_ENGINE_DISP,
+
         NVDEV_SUBDEV_NR,
 };
 
diff --git a/drivers/gpu/drm/nouveau/core/subdev/device/base.c b/drivers/gpu/drm/nouveau/core/subdev/device/base.c
index 7bf6f3760b9..ca9a4648bd8 100644
--- a/drivers/gpu/drm/nouveau/core/subdev/device/base.c
+++ b/drivers/gpu/drm/nouveau/core/subdev/device/base.c
@@ -96,14 +96,13 @@ nouveau_devobj_ctor(struct nouveau_object *parent,
                     struct nouveau_object **pobject)
 {
         struct nouveau_client *client = nv_client(parent);
-        struct nouveau_object *subdev = NULL;
         struct nouveau_device *device;
         struct nouveau_devobj *devobj;
         struct nv_device_class *args = data;
         u64 disable, boot0, strap;
         u64 mmio_base, mmio_size;
         void __iomem *map;
-        int ret, i;
+        int ret, i, c;
 
         if (size < sizeof(struct nv_device_class))
                 return -EINVAL;
@@ -234,34 +233,43 @@ nouveau_devobj_ctor(struct nouveau_object *parent,
         }
 
         /* ensure requested subsystems are available for use */
-        for (i = 0; i < NVDEV_SUBDEV_NR; i++) {
+        for (i = 0, c = 0; i < NVDEV_SUBDEV_NR; i++) {
                 if (!(oclass = device->oclass[i]) || (disable & (1ULL << i)))
                         continue;
 
                 if (!device->subdev[i]) {
                         ret = nouveau_object_ctor(nv_object(device), NULL,
-                                                  oclass, NULL, i, &subdev);
+                                                  oclass, NULL, i,
+                                                  &devobj->subdev[i]);
                         if (ret == -ENODEV)
                                 continue;
                         if (ret)
                                 return ret;
 
-                        if (nv_iclass(subdev, NV_ENGINE_CLASS))
-                                nouveau_subdev_reset(subdev);
+                        if (nv_iclass(devobj->subdev[i], NV_ENGINE_CLASS))
+                                nouveau_subdev_reset(devobj->subdev[i]);
                 } else {
-                        nouveau_object_ref(device->subdev[i], &subdev);
+                        nouveau_object_ref(device->subdev[i],
+                                          &devobj->subdev[i]);
                 }
 
-                if (!nv_iclass(subdev, NV_ENGINE_CLASS)) {
-                        ret = nouveau_object_inc(subdev);
-                        if (ret) {
-                                nouveau_object_ref(NULL, &subdev);
-                                return ret;
+                /* note: can't init *any* subdevs until devinit has been run
+                 * due to not knowing exactly what the vbios init tables will
+                 * mess with.  devinit also can't be run until all of its
+                 * dependencies have been created.
+                 *
+                 * this code delays init of any subdev until all of devinit's
+                 * dependencies have been created, and then initialises each
+                 * subdev in turn as they're created.
+                 */
+                while (i >= NVDEV_SUBDEV_DEVINIT_LAST && c <= i) {
+                        struct nouveau_object *subdev = devobj->subdev[c++];
+                        if (subdev && !nv_iclass(subdev, NV_ENGINE_CLASS)) {
+                                ret = nouveau_object_inc(subdev);
+                                if (ret)
+                                        return ret;
                         }
                 }
-
-                nouveau_object_ref(subdev, &devobj->subdev[i]);
-                nouveau_object_ref(NULL, &subdev);
         }
 
         return 0;