[haiku-development] Re: Dropping intel_gart (and agp_gart)
- From: Adrien Destugues <pulkomandy@xxxxxxxxx>
- To: haiku-development@xxxxxxxxxxxxx
- Date: Tue, 3 Nov 2015 07:17:42 +0100
On Tue, Nov 03, 2015 at 03:25:02AM +0000, Alexander von Gluck IV wrote:
I wanted to collect some thoughts on dropping agp_gart.
intel_express is still lugging around agp_gart for modern chipsets.
Classic Intel AGP chipsets exist as PCI devices with an extra
layer to speed up transfers. Without agp_gart the bus simply operates
at the slower pci speeds.[1]
This means "a lot slower" (like 2x or 4x, at least) on AGP based
machines (the slow ones, where we really need that extra speed).
We've been carrying around agp_gart a bit longer than we should of
as intel_extreme performs all of its gtt work through agp_gart.
Since us leveraging 3d hardware rendering on classic Intel AGP
chipsets doesn't seem likely, i'd personally like to see agp_gart
disappear as it layers on lots of added complexity.
If I were to rip out agp_gart (and still have a functional
intel_extreme driver) would anyone care?
I would keep it around for the old devices (I think the i810 driver also
uses it?) and bypass it for the new ones (i915 and later as mentionned
in your IRC logs) if possible.
However, if that means doing the same work in the intel driver anyway,
is there a point? Sometimes it's nice to keep unrelated things
separated. The intel_extreme driver is simple and focused on setting
video modes, because the gart stuff is nicely split out in a separate
driver. I think this helps understanding the code and design?
--
Adrien.
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