device property: add description of fwnode cases

There are only four valid fwnode cases which are
- primary --> secondary --> -ENODEV
- primary --> NULL
- secondary --> -ENODEV
- NULL

dev->fwnode should be converted between the 4 cases above no matter
how/when set_primary_fwnode() and set_secondary_fwnode() are called.
Describe it in the code so people will keep it in mind.

Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
[ rjw: Comment edit ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Bard Liao 2021-01-05 17:11:46 +08:00 committed by Rafael J. Wysocki
parent 47f4469970
commit 3f7bddaf5d

View File

@ -4414,6 +4414,12 @@ static inline bool fwnode_is_primary(struct fwnode_handle *fwnode)
*
* Set the device's firmware node pointer to @fwnode, but if a secondary
* firmware node of the device is present, preserve it.
*
* Valid fwnode cases are:
* - primary --> secondary --> -ENODEV
* - primary --> NULL
* - secondary --> -ENODEV
* - NULL
*/
void set_primary_fwnode(struct device *dev, struct fwnode_handle *fwnode)
{
@ -4432,6 +4438,7 @@ void set_primary_fwnode(struct device *dev, struct fwnode_handle *fwnode)
} else {
if (fwnode_is_primary(fn)) {
dev->fwnode = fn->secondary;
/* Set fn->secondary = NULL, so fn remains the primary fwnode */
if (!(parent && fn == parent->fwnode))
fn->secondary = NULL;
} else {