[Intel-gfx] [PATCH 3/3] agp/intel-gtt: Only register fake agp driver for gen1

Chris Wilson chris at chris-wilson.co.uk
Tue Jan 26 12:58:12 PST 2016

On Tue, Jan 26, 2016 at 07:49:56PM +0100, Daniel Vetter wrote:
> The fake agp driver for the intel graphics gart is only needed for ums
> support. And we ditched that a long time ago:
> commit 03dae59c72ffffd8ef6e005f48ba356c863e0587
> Author: Daniel Vetter <daniel.vetter at ffwll.ch>
> Date:   Wed Jul 23 16:27:25 2014 +0200
>     drm/i915: Ditch UMS config option
> With this there's no longer the problem that 2 drivers (fake agp
> driver and the drm/i915 driver) fight over the same piece, which fixes
> apparent dma leaks detected by CONFIG_DMA_API_DEBUG.
> Note that the leak isn't real since intel-gtt refcounts and will tear
> down eventually. But the debug code assumes that when the i915 driver
> unbinds from the pci device everything should be gone. Which isn't the
> case if we have intel-agp enabled - userspace might need it. But by
> ditching this intel-gtt setup and teardown is completely tied to the
> livetime of the "real" driver.
> While at it untangle the init ordering a bit - the fake agp wouldn't
> be initialized correctly if i915.ko loads first. Which isn't a problem
> since when i915 loads in kms mode you won't need the fake agp support
> needed by the ums driver ...
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=93793
> Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>

Chris Wilson, Intel Open Source Technology Centre

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