From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Du, Changbin" <changbin.du@intel.com>
Subject: Re: [PATCH] drm/i915: Add interface to reserve fence
 registers for vGPU
Date: Thu, 31 Aug 2017 11:21:02 +0800
Message-ID: <20170831032101.GA7935@intel.com>
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To: Chris Wilson <chris@chris-wilson.co.uk>
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Hi chris,

On Wed, Aug 30, 2017 at 10:27:18AM +0100, Chris Wilson wrote:
> Quoting changbin.du@intel.com (2017-08-30 09:54:21)
> > This patch added two new api to the fence management code:
> >  - i915_reserve_one_fence() will try to find a free fence from fence_li=
st
> >    and force-remove vma if need.
> >  - i915_giveback_reserved_fence() reclaim a reserved fence after vGPU h=
as
> >    finished.
>=20
> Symmetry: reserve_fence, unreserve_fence.
>
ok, I will rename the functions.

> We need a safeguard here so that the host is able to always able allocate
> to allocate a fence for the display engine. (That requirement should be
> quite soft for modern hw, nevertheless it should be in the design to
> prevent overuse from leading to an unusable system.)
> -Chris
Yes, agree. Is there any other components always need a fence ready? otherw=
ise,
I will add a safeguard to ensure at least 1 fence register remained for hos=
t.

--=20
Thanks,
Changbin Du

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