On Mon, Dec 07, 2020 at 11:25:03AM -0800, Saravana Kannan wrote: > On Sat, Dec 5, 2020 at 11:48 PM Leon Romanovsky <leon@xxxxxxxxxx> wrote: > > > > On Fri, Nov 20, 2020 at 06:02:23PM -0800, Saravana Kannan wrote: > > > Add support for creating supplier-consumer links between fwnodes. It is > > > intended for internal use the driver core and generic firmware support > > > code (eg. Device Tree, ACPI), so it is simple by design and the API > > > provided is limited. > > > > > > Signed-off-by: Saravana Kannan <saravanak@xxxxxxxxxx> > > > --- > > > drivers/base/core.c | 98 ++++++++++++++++++++++++++++++++++++++++++ > > > drivers/of/dynamic.c | 1 + > > > include/linux/fwnode.h | 14 ++++++ > > > 3 files changed, 113 insertions(+) > > > > > > diff --git a/drivers/base/core.c b/drivers/base/core.c > > > index 401fa7e3505c..e2b246a44d1a 100644 > > > --- a/drivers/base/core.c > > > +++ b/drivers/base/core.c > > > @@ -50,6 +50,104 @@ static LIST_HEAD(wait_for_suppliers); > > > static DEFINE_MUTEX(wfs_lock); > > > static LIST_HEAD(deferred_sync); > > > static unsigned int defer_sync_state_count = 1; > > > +static DEFINE_MUTEX(fwnode_link_lock); > > > + > > > +/** > > > + * fwnode_link_add - Create a link between two fwnode_handles. > > > + * @con: Consumer end of the link. > > > + * @sup: Supplier end of the link. > > > + * > > > + * Create a fwnode link between fwnode handles @con and @sup. The fwnode link > > > + * represents the detail that the firmware lists @sup fwnode as supplying a > > > + * resource to @con. > > > + * > > > + * The driver core will use the fwnode link to create a device link between the > > > + * two device objects corresponding to @con and @sup when they are created. The > > > + * driver core will automatically delete the fwnode link between @con and @sup > > > + * after doing that. > > > + * > > > + * Attempts to create duplicate links between the same pair of fwnode handles > > > + * are ignored and there is no reference counting. > > > > Sorry to ask, but why is that? > > Isn't this a programmer error? > > No, not a programmer error. > > One firmware node can point to the same supplier many times. For > example, the consumer can be using multiple clocks from the same > supplier clock controller. In the context of fw_devlink, there's no > reason to keep track of each clock dependency separately because we'll > be creating only one device link from fwnode link. So multiple fwnode > link attempts between the same two devices are just treated as one > instance of dependency. I hope that clarifies things. Yes, thanks. > > -Saravana
