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: Simon Glass sjg@chromium.org ---
Changes in v4: None Changes in v3: None Changes in v2: None
drivers/core/device.c | 4 +++- drivers/core/uclass.c | 7 ++++++- 2 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/drivers/core/device.c b/drivers/core/device.c index 4f060ee..eefd1cb 100644 --- a/drivers/core/device.c +++ b/drivers/core/device.c @@ -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) diff --git a/drivers/core/uclass.c b/drivers/core/uclass.c index f63ff59..e800c28 100644 --- a/drivers/core/uclass.c +++ b/drivers/core/uclass.c @@ -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", id); - 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. + */ + return -EPFNOSUPPORT; } uc = calloc(1, sizeof(*uc)); if (!uc)