On Thu, Jul 04, 2013 at 11:44:41AM +0200, Sebastian Hesselbarth wrote:
On 07/04/13 11:30, Sascha Hauer wrote:
On Thu, Jul 04, 2013 at 10:11:31AM +0100, Russell King wrote:
On Thu, Jul 04, 2013 at 10:58:17AM +0200, Sascha Hauer wrote:
On Thu, Jul 04, 2013 at 09:40:52AM +0100, Russell King wrote:
Wrong. Please read the example with the diagrams I gave. Consider what happens if you have two display devices connected to a single output, one which fixes the allowable mode and one which _can_ reformat the selected mode.
What you describe here is a forced clone mode. This could be described in the devicetree so that a driver wouldn't start before all connected displays (links) are present, but this should be limited to the affected path, not to the whole componentized device.
Okay, to throw a recent argument back at you: so what in this scenario if you have a driver for the fixed-mode device but not the other device?
It's exactly the same problem which you were describing to Sebastian just a moment ago with drivers missing from the supernode approach - you can't start if one of those "forced clone" drivers is missing.
Indeed, then you will see nothing on your display, but I rather make this setup a special case than the rather usual case that we do not have compiled in all drivers for all devices referenced in the supernode.
The super-node links SoC internal devices that do not necessarily match with the subsystem driver. You have one single DRM driver exploiting several device nodes for a single video card.
But you need one device node to hook the driver to.
Currently on i.MX we use a platform_device for this purpose.
Sascha