From mboxrd@z Thu Jan  1 00:00:00 1970
From: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Subject: Re: [PATCH 09/17] drm/radeon: use common fence implementation for
 fences
Date: Tue, 22 Jul 2014 16:27:01 +0200
Message-ID: <53CE74B5.3000201@canonical.com>
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To: =?ISO-8859-1?Q?Christian_K=F6nig?= <christian.koenig@amd.com>, =?ISO-8859-1?Q?Christian_K=F6nig?= <deathsimple@vodafone.de>, Dave Airlie <airlied@gmail.com>, Thomas Hellstrom <thellstrom@vmware.com>, nouveau <nouveau@lists.freedesktop.org>, LKML <linux-kernel@vger.kernel.org>, dri-devel <dri-devel@lists.freedesktop.org>, Ben Skeggs <bskeggs@redhat.com>, "Deucher, Alexander" <alexander.deucher@amd.com>
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op 22-07-14 16:24, Christian K=F6nig schreef:
>> No, you really shouldn't be doing much in the check anyway, it's meant t=
o be a lightweight check. If you're not ready yet because of a lockup simpl=
y return not signaled yet.
> It's not only the lockup case from radeon I have in mind here. For usersp=
ace queues it might be necessary to call copy_from_user to figure out if a =
fence is signaled or not.
>
> Returning false all the time is probably not a good idea either.
Having userspace implement a fence sounds like an awful idea, why would you=
 want to do that?

A fence could be exported to userspace, but that would only mean it can wai=
t for it to be signaled with an interface like poll..

~Maarten