10 gru 2014 17:16 "Russell King - ARM Linux" <<a href="mailto:linux@arm.linux.org.uk">linux@arm.linux.org.uk</a>> napisał(a): > > On Wed, Dec 10, 2014 at 04:48:18PM +0100, Andrzej Hajda wrote: > > 3. There are drivers which can work without specific resource, but if > > the resource becomes available/unavailable it can do some additional stuff. > > An example of such driver is DRM driver (more precisely drm_connector) - > > it can start without attached drm_panel, but if the panel becomes available it > > can react by generating HPD event and start using it. > > Bad example, and actually incorrect. DRM connectors are referenced in > userspace by an IDR number, which can be re-used in the case of a > connector appearing, disappearing, and then a different connector > re-appearing. But it is not about reappearing of drm_connector, it is about reappearing of drm_panel which is fortunately not a part of drm driver. Connector here is only consumer of drm_panel which should have possibility to receive notifications on panel (dis-)appearance. Regards Andrzej > > DRM really is *not* safe to hotplug like this: DRM is more a card-level > thing, which is why we have the component helpers - which allow us to > merge several devices into one logical card-like device in a generic > manner. > > DRM needs a stable picture of the CRTCs, encoders and connectors, which > should _never_ change during the lifetime of the DRM device. Devices > attached to connectors can be hotplugged, but that's about the limit of > hot-plugging in DRM. > > -- > FTTC broadband for 0.8mile line: currently at 9.5Mbps down 400kbps up > according to <a href="http://speedtest.net">speedtest.net</a>. > _______________________________________________ > dri-devel mailing list > <a href="mailto:dri-devel@lists.freedesktop.org">dri-devel@lists.freedesktop.org</a> > <a href="http://lists.freedesktop.org/mailman/listinfo/dri-devel">http://lists.freedesktop.org/mailman/listinfo/dri-devel</a>