10 gru 2014 17:16 "Russell King - ARM Linux" <linux@xxxxxxxxxxxxxxxx> 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 speedtest.net.
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