Seth Forshee wrote: > 1. On many Macbook models the firmware isn't putting LVDS information > in opregion. Reading the EDID during device initialization also > fails since the DDC is muxed to the DGPU, so i915 concludes there's > no LVDS and doesn't register an LVDS connector at all. I also think > it was impossible to register a new connector at a later time, > though I'm not sure about that.
On a different thread, Chris is helping me write a series to fill in the switcheroo-reprobe callback with corresponding get-edid functions. Do you think it'll be useful? > 2. If i915 is forced to register the LVDS connector (say via a quirk) > it still may not know the panel mode and guesses something rather > conservative. This mode it assumes is used to allocate framebuffer > memory, which is likely to end up being too small, and I don't think > there was any support for resizing it later. This resulted in VTs > not working because there isn't enough framebuffer memory for the > mode they're trying to use. I saw your quirk-patch (https://lkml.org/lkml/2012/8/4/128). Seems like a rather inelegant approach to register the LVDS connector unconditionally during initialization; I'll try to avoid going down this road. > 3. So what is really wanted is to be able to mux just the DDC over to > the IGPU when the device is initialized to read the panel mode. One > possible problem is that the hw might not support muxing the DDC > separately, but Apple hw does so we'll ignore that for now. The > basic code for muxing only the DDC isn't too difficult, and I had > some patches for this at one point. The problem is that the handler > must register with vga_switcheroo before this is possible, so > there's a module initialization ordering issue that wasn't easily > solved. Maybe now it would be possible to do something with > EPROBE_DEFER, though I'm not sure how i915 would know whether or not > it should wait for a switcheroo handler. I didn't understand much of the above; I suppose it'll start making sense when I'm deeper into the issue. > I just didn't have enough time to spend on this issue to work through > all of this. I also never looked at doing this with eDP, which is what I > thought all the Macbooks have been using for the last couple of years. > Are you sure your machine uses LVDS and not eDP? I just assumed that it was LVDS; turns out it's eDP. I have time to work on the issue now, so I'd appreciate any help I can get. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
