Mode setting & EGL

[Adam Jackson]

On Tuesday 15 March 2005 22:32, Benjamin Herrenschmidt wrote:
> Hi !
>
> I just subscribed to the list and in the middle of reading the archives.
> Just a few quick commentes/notes about the mode setting stuff from what
> I've read. Maybe just stuffs I've overlooked though, I haven't had time
> to read the EGL spec yet.
>
>  - Mode setting has an impact on data cached in fb memory. It can be
> (and will be) destructive. See the (long) thread going on on x.org &
> fbdev lists for details.
>
>  - Ideally, mode setting should be implemented in a separate library on
> top of fbdev ioctl's and drm, and EGL using that library, no ?

Correct, for the DRI drivers at least.  We want EGL to have a consistent way 
to specify a screen surface's attributes, from the _application_'s 
perspective.  The EGL implementation is just going to turn around and hand 
the request to the userspace driver component anyway.  So the issue is making 
sure that the interface provided by this notional libmodeset is sufficient 
for what an EGL app wants to do.

I really don't care _how_ the fbdev layer implements all this.  I just want 
enough feedback to know if a certain attribute is absolutely not possible to 
expose, so we don't write something unimplementable into the extension spec.  
If the card can't tell me which monitor is painted pink and which one is 
painted green, then we need to not let applications select mode based on 
monitor paint scheme.

- ajax
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