On Wed, Oct 29, 2014 at 10:14:37AM +0100, Thierry Reding wrote:
On Wed, Oct 29, 2014 at 09:57:02AM +0100, Daniel Vetter wrote:
That makes the entire thing a bit non-trivial, which is why I think it would be better as some generic helper. Which then gets embedded or instantiated for specific cases, like dt&drm_panel or dt&drm_bridge. Or maybe even acpi&drm_bridge, who knows ;-)
I worry a little about type safety. How will this generic helper know what registry to look in for? Or conversely, if all these resources are added to a single registry how do you know that they're of the correct type? Failing to ensure this could cause situations where you're asking for a panel and get a bridge in return because you've wrongly wired it up in device tree for example.
But perhaps if both the registry and the device parts are turned into helpers we could still have a single core implementation and then instantiate that for each type, something roughly like this:
struct registry { struct list_head list; struct mutex lock; };
struct registry_record { struct list_head list; struct module *owner; struct kref *ref;
struct device *dev;};
int registry_add(struct registry *registry, struct registry_record *record) { ... try_module_get(record->owner); ... }
struct registry_record *registry_find_by_of_node(struct registry *registry, struct device_node *np) { ... kref_get(...); ... }
That way it should be possible to embed these into other structures, like so:
struct drm_panel { struct registry_record record; ... };
static struct registry drm_panels;
int drm_panel_add(struct drm_panel *panel) { return registry_add(&drm_panels, &panel->record); }
struct drm_panel *of_drm_panel_find(struct device_node *np) { struct registry_record *record;
record = registry_find_by_of_node(&drm_panels, np); return container_of(record, struct drm_panel, record);}
Is that what you had in mind?
Yeah I've thought that we should instantiate using macros even, so that we have per-type registries. So you'd smash the usual set of DECLARE/DEFINE_AUX_DEV_REGISTRY into headers/source files, and they'd take a (name, key, value) tripled. For the example here(of_drm_panel, struct device_node *, struct drm_panel *) or similar. I might be hand-waving over a few too many details though ;-)
Cheers, Daniel