Commit 3346c876 authored by Simon Glass's avatar Simon Glass

dm: Improve handling of a missing uclass

When a uclass definition is missing, no drivers in that uclass can operate.
This can happen if a board has a strange collection of options (e.g. the
driver is enabled but the uclass is not).

Unfortunately this is very confusing at present. Starting up driver model
results in a -ENOENT error, which is pretty generic. Quite a big of digging
is needed to get to the root cause.

To help with this, change the error to a very strange one with no other
users in U-Boot. Also add a debug message.
Signed-off-by: default avatarSimon Glass <>
parent e3563f2e
......@@ -39,8 +39,10 @@ int device_bind(struct udevice *parent, const struct driver *drv,
return -EINVAL;
ret = uclass_get(drv->id, &uc);
if (ret)
if (ret) {
debug("Missing uclass for driver %s\n", drv->name);
return ret;
dev = calloc(1, sizeof(struct udevice));
if (!dev)
......@@ -58,7 +58,12 @@ static int uclass_add(enum uclass_id id, struct uclass **ucp)
if (!uc_drv) {
debug("Cannot find uclass for id %d: please add the UCLASS_DRIVER() declaration for this UCLASS_... id\n",
return -ENOENT;
* Use a strange error to make this case easier to find. When
* a uclass is not available it can prevent driver model from
* starting up and this failure is otherwise hard to debug.
uc = calloc(1, sizeof(*uc));
if (!uc)
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