[PATCH] randr: add provider object (v7)
airlied at gmail.com
Tue Jul 3 07:10:14 PDT 2012
On Tue, Jul 3, 2012 at 2:57 PM, Alex Deucher <alexdeucher at gmail.com> wrote:
> On Tue, Jul 3, 2012 at 7:57 AM, Dave Airlie <airlied at gmail.com> wrote:
>> (forgot list first time I sent this).
>> On Mon, Jul 2, 2012 at 10:03 PM, Keith Packard <keithp at keithp.com> wrote:
>>> Dave Airlie <airlied at gmail.com> writes:
>>>> On Mon, Jul 2, 2012 at 8:54 PM, Keith Packard <keithp at keithp.com> wrote:
>>>>> Dave Airlie <airlied at gmail.com> writes:
>>>>>> Yes thats going to be the standard on switchable GPU machines, two masters
>>>>>> and the ability to jump between them. In that case max master is one, and you'd
>>>>>> have to set the provider roles. If maxmaster > 1 then xinerama
>>>>>> emulation is available.
>>>>> In those machines, isn't the limitation that only one of them can drive
>>>>> the LVDS panel at a time? Can't you have the internal GPU driving the
>>>>> LVDS while the external GPU drives other outputs?
>>>> Yes but you don't configure it in xinerama mode for that, there are
>>>> mux and muxless configurations.
>>> I think I understand what the hardware does now, just trying to figure
>>> out how to provide a reasonable description of that to applications
>>> while not just providing a big 'muxless/muxed' switch, which seems
>>> restricted to precisely how the hardware that we have works today.
>>>> In mux configuration, you switch the mux between GPUs when the master
>>>> is switched.
>>> Right, the mux just rewires things so that the other GPU is hooked up to
>>> the LVDS. I'd expect the LVDS outputs to reflect a suitable connection
>>> status for these changes.
>>> The only question is how you drive the mux switch. Is this switch
>>> selectable per-output? Or is is global? And, how do we label which
>>> outputs are affected by a global switch?
>> We don't really know with 100% certainty since the specs for all these
>> things are closed. We've done a lot of RE work, and it mostly appears
>> to be a single global switch that turns any connected outputs. There is
>> a table in the intel bios which can tell you about which outputs are muxed
>> etc, but this isn't always present. Again we also have laptops that have
>> a mux but don't expose this table, as they only have the MUX so the
>> BIOS can pick IGP/discrete for Vista, and Windows 7 operates in
>> muxless mode.
>> The current problem is I'm not sure any OS exposes muxless and mux
>> in one OS. Mac OSX always uses muxed, Vista the same, and I think
>> Windows 7 always exposes muxless if the bios reports optimus support
>> or the AMD equivalent.
> All new AMD systems are muxless and I suspect most other vendors are
> doing the same. I'm wondering if there is any reason to bother with
> proper muxed support at all? We should be able to treat muxed systems
> as muxless just fine.
Apple hw is the only one I know off persisting with a muxed design,
Whether it buys us much supporting the mux on it I'm not sure, I've no
idea to what degree they power down the intel hardware on it.
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