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Re: TTM merging?

From:  Dave Airlie <>
To:  =?iso-8859-15?Q?Thomas_Hellstr=F6m?= <>
Subject:  Re: TTM merging?
Date:  Tue, 13 May 2008 23:46:10 +0100 (IST)
Message-ID:  <>
Cc:  DRI <>, Dave Airlie <>
Archive-link:  Article

> > 1) I feel there hasn't been enough open driver coverage to prove it. So far
> > we have done an Intel IGD, we have a lot of code that isn't required for
> > these devices, so the question of how much code exists purely to support
> > poulsbo closed source userspace there is and why we need to live with it.
> > Both radeon and nouveau developers have expressed frustration about the
> > fencing internals being really hard to work with which doesn't bode well for
> > maintainability in the future.
> >   
> OK. So basically what I'm asking is that when we have full-feathered open
> source drivers available that
> utilize TTM, either as part of DRM core, or, if needed, as part of
> driver-specific code, do you see anything
> else that prevents that from being pushed? That would be very valuable to know
> for anyone starting porting work. ?

I was hoping that by now, one of the radeon or nouveau drivers would have 
adopted TTM, or at least demoed something working using it, this hasn't 
happened which worries me, perhaps glisse or darktama could fill in on 
what limited them from doing it. The fencing internals are very very scary 
and seem to be a major stumbling block.

I do worry that TTM is not Linux enough, it seems you have decided that we 
can never do in-kernel allocations at any useable speed and punted the 
work into userspace, which makes life easier for Gallium as its more like 
what Windows does, but I'm not sure this is a good solution for Linux.

The real question is whether TTM suits the driver writers for use in Linux 
desktop and embedded environments, and I think so far I'm not seeing 
enough positive feedback from the desktop side.

Also wrt the i915 driver it has too many experiments in it, the i915 users 
need to group together and remove the codepaths that make no sense and 
come up with a ssuitable userspace driver for it, remove all unused 
fencing mechanisms etc..


> /Thomas

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