EGL_MESA_screen_surface proposal

[Alex Deucher]

On Wed, 16 Mar 2005 20:51:29 -0500, Jon Smirl <jonsmirl at gmail.com> wrote:
> On Thu, 17 Mar 2005 12:29:16 +1100, Benjamin Herrenschmidt
> <benh at kernel.crashing.org> wrote:
> > I wouldn't do something as complex I suppose for EGL, but I would at
> > least put clearly in the spec that doing a mode setting may not result
> > in that actual mode beeing reallly set. That is the user is expected to
> > re-query for the mode after setting it. The driver may have had to do
> > something else at the last minute due to whatever internal problem,
> > error, out of resource, etc...
> 
> I would flip this around. The modes can always be set. What fails it
> attaching a surface to the mode. It's the surface that carries the
> depth information and causes the bandwidth to be exceeded.
> 
> It might be worth looking at a model where mode and surface setting is
> combined. Or mode sets are not applied until a surface set follows. I
> don't like the transactional hole of setting the mode while still
> using the old surface.
> 
> In another mail I tossed out the idea of adding a 'surface=name'
> attribute to mode setting. fbdev would implement a special surface
> named 'default' which would alway morph to match the mode. When DRM is
> running 'default' would be replaced by named surfaces implementing
> specific formats.
> With this model when a mode is set in fbdev it would carry an implied
> 'surface=default'.
> 
> On another topic, if I understand my LCD correctly it is always
> updating at 60Hz no matter what I set the refresh to. What it does is
> let me update the buffer at 72Hz but it is still displayed at 60Hz.
> 60Hz doesn't flicker because LCDs don't use phosphors. Given this,
> it's always best to update my display at 60Hz. All that happens at
> 72Hz is that 17% of the bits sent to the monitor never get displayed.
> 

You LCD may behave like that, but the ones I have at work advertise 75
Hz but they look like crap (fuzzy, etc.) if they are not run at 60Hz. 
To use them with X I have to force them to 60hz other wise they end up
at 75 Hz.

> 
> --
> Jon Smirl
> jonsmirl at gmail.com