randr provider object

[Dave Airlie]

>>
>> I'm not sure I can really fix that with this though, thats a whole
>> project by itself, and if fixing the crappy history of X decisions
>> before we try and move on, we'll never get anywhere.
>>
>> The reason for exclusive_master is just GPU switching, since it needs
>> to be an atomic operation, we don't want to keep both GPUs running,
>> maybe I can add a separate protocol request for GPU switch, but I
>> don't think it makes a huge amount of sense either.
>
>
> My concern is how you're going to build this programmatically if you keep
> with a poke-one-thing model, I just envision intermediate states that don't
> make a ton of sense on their own but that we'd end up needing to allow.
>  What do you imagine the sequence of requests looking like?

I forsee the client side being smart like it is now,

So user plugs in a new output device:
client gets told something changed, rescans resources/providers.
notices new provider with output slave support and a crtc (and
outputs) - I think this is why I wanted to provide crtc/output lists,
since the crtc/outputs aren't bound to the screen yet.
client bind provider as a client slave, new crtc/output appears in
resource list.
client sets mode on new crtcs that appear, or offers them to user in gui app.

User wants to offload rendering:
launcher app notices an offload provider on the screen, sets env var,
launches DRI2 app.

User wants to switch GPUs to discrete:
Notices an offload slave that can be master,
requests it becomes master, and the current master becomes an output
slave (thanks optimus).

User wants to switch GPUs back to Integrated
Notices an output slave that can be master,
requests it becomse master: and current master becomes an offload
slave (thanks optimus)

plugs in an external monitor requiring a GPU switch to use (thanks optimus):
not sure how best to deal with this, since I've no idea what the
standard wiring is. On the my sample size of one laptop, the EDID is
wired to the Intel GPU as well, so in theory we could poll via the
Intel GPU to see if an external monitor appears on the powereed off
GPU. There may also be some way to power up the DGPU on HPD irqs, but
I've no idea.
Assuming we can notice this, power up the DGPU, we probably need some
sort of event to send to the client saying switch required for current
HW configuration. Then the client sends the switch command as per the
user doing it.

Dave.