Re: [Linux-fbdev-devel] [PATCH] aty128fb 15/16 bit cleanup

[Sven L. <lu...@dp...>]

On Wed, Jun 27, 2001 at 09:41:34AM -0700, James Simmons wrote:
> 
> > If i want to do dma with this library, should i need to use the drm, or is
> > some other possibilities available ?
> 
> For now yes. First the fbdev cleanup then the merging of DRI and fbdev.
> The merging has to be done very carefully since hardware various quite
> dramatically when going from PDAs to high end rendering farms. 

You are speaking about the merging as something that will happen inevitably,
and quite soon also. How is it really, do the DRI people know you intent to
merge the drm and fbdev ? What do they think about it ? I suppose it is quite
political stuff, isn't it ?

> > How will a user-space library using the accel engine (it would clearly need a
> > little 'driver' for each chip) cohabit with the acceleration used with fbcon ?
> > 
> > Also i suppose by "graphic" mode you are speaking about X, and by "text" mode,
> > you are speaking about fbcon ?
> 
> Yes. fbcon would shutdown when going into "graphics" mode. This would
> prevent any conflicts.

What about if an app wants to take over let's say the top 4/3 orsomething such
of the screen (in order to open a 16/9 or whatever video playback window or
something such) and keep fbcon active in the lower part, in order for the app
to do it's I/O ?

> > Who will be responsible for setting the accel engine in a different state ? as
> > XFree clearly thinks it is his responsability to do such. Or are you thinking
> > only about the new X server ?
> 
> XFree86 is wrong in this department. The console system should handle it.

Ah, sure, but Xfree86 is the main app out there, and it is they who really own
the linux desktop. And they also have the most visibility right now.

> Who better to the knwo the hardware of the console system than the console
> system itself. As linux is ported to more and more platforms less and less
> of that graphics hardware will support vga text mode. Even when you place
> your video card in a vga text mode besides 80x25 XFree86 has a hard time.
> It makes to many assumptions which end up being wrong. Even without my
> console changes XFree86 is broken. With my changes it still will be
> broken. It just in the case of the new console code it reset the mode
> itself and in the process fix any stupid mistakes XFree86 made.

yes, fbdev support in linux needs some work, but it can be fixed, if someone
is willing to do the job.

But again, X actually thinks that they are responsible for handling the card,
and the DRI follows their lead. It is the X driver who handles the switch
between the 2D and various 3D contexts. How will using hardware access on the
console handle this ?

Ok, i guesss using standard register writing should work without problem, but
what about the dma stuff ? if you use the drm you interact with X.

That said, all this is not really all that clear in my mind right now.

Friendly,

Sven Luther
>