On Fri, Oct 31, 2014 at 04:51:43PM +0100, Daniel Vetter wrote:
> 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 ;-)
Okay, I'll take a stab at this and see if I can convert DRM panel to it.
Thierry
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