[Intel-gfx] Async eDP init

[Jesse Barnes]

On 03/19/2015 10:42 AM, Daniel Vetter wrote:
> On Wed, Mar 18, 2015 at 11:41:48AM -0700, Jesse Barnes wrote:
>> This updates my old patch for this, but w/o fixing the locking issue
>> Ville mentioned.  In looking at it, it seems like the sync point should
>> be at a higher level, maybe at the level of the atomic mode setting async
>> serialization points?  Another possibility would be to make it a lazy
>> init type function, sprinkled about but only running once when we first
>> need it.
>>
>> Any thoughts from anyone?  I don't think I can just do a lock drop here,
>> since other threads may jump in and mess with underlying state.  That
>> shouldn't affect the eDP state we fill out, but may affect the state the
>> caller depended on in the first place...
> 
> Imo the real issue is that we register a connector and then throw it away
> again. Not that big a problem any more since mst dp happened meanwhile but
> still might result in confusion.
> 
> I think we should try to at least get the "is this an edp or not" question
> right, and only postpone the other init steps. So maybe start with making
> that edp failed to init issue really loud and then rip it out?
> 
> Postponing all the other init work would be comparitively a lot easier I
> think.

I didn't view that as a big issue, but it should be easy to solve.  I
think the synchronization problems are still just as thorny though, even
with the question of is_edp() solved early.  The eDP init is kind of
like a boot time mode set, but one that needs to complete before any
activity on the port.

I'll check those init paths; hopefully answering is_edp() won't have a
bunch of delay in itself.

Jesse