From: "Christian König" <christian.koenig@amd.com>
To: "Daniel Vetter" <daniel.vetter@ffwll.ch>,
"Christian König" <deathsimple@vodafone.de>
Cc: Dave Airlie <airlied@gmail.com>,
Maarten Lankhorst <maarten.lankhorst@canonical.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>
Subject: Re: [Nouveau] [PATCH 09/17] drm/radeon: use common fence implementation for fences
Date: Tue, 22 Jul 2014 17:35:06 +0200 [thread overview]
Message-ID: <53CE84AA.9030703@amd.com> (raw)
In-Reply-To: <CAKMK7uG1d31zU_i__wc+Yq46A0x0tPeKnMBs+NHSmHS82uMsXQ@mail.gmail.com>
Am 22.07.2014 17:17, schrieb Daniel Vetter:
> On Tue, Jul 22, 2014 at 3:45 PM, Christian König
> <deathsimple@vodafone.de> wrote:
>>> Would that be something you can agree to?
>>
>> No, the whole enable_signaling stuff should go away. No callback from the
>> driver into the fence code, only the other way around.
>>
>> fence->signaled as well as fence->wait should become mandatory and only
>> called from process context without holding any locks, neither atomic nor
>> any mutex/semaphore (rcu might be ok).
> So for the enable_signaling, that's optional already. It's only for
> drivers that don't want to keep interrupts enabled all the time. You
> can opt out of that easily.
>
> Wrt holding no locks at all while calling into any fence functions,
> that's just not going to work out. The point here is to make different
> drivers work together and we can rework all the ttm and i915 code to
> work locklessly in all cases where they need to wait for someone to
> complete rendering. Or at least I don't think that's feasible. So if
> you insist that no one might call into radeon code then we simply need
> to exclude radeon from participating in any shared fencing. But that's
> a bit pointless.
>
>>> Like I've said I think restricting the insanity other people are willing
>>> to live with just because you don't like it isn't right. But it is
>>> certainly right for you to insist on not being forced into any such
>>> design. I think the above would achieve this.
>>
>> I don't think so. If it's just me I would say that I'm just to cautious and
>> the idea is still save to apply to the whole kernel.
>>
>> But since Dave, Jerome and Ben seems to have similar concerns I think we
>> need to agree to a minimum and save interface for all drivers.
> Well I haven't yet seen a proposal that actually works.
How about this:
Drivers exporting fences need to provide a fence->signaled and a
fence->wait function, everything else like fence->enable_signaling or
calling fence_signaled() from the driver is optional.
Drivers wanting to use exported fences don't call fence->signaled or
fence->wait in atomic or interrupt context, and not with holding any
global locking primitives (like mmap_sem etc...). Holding locking
primitives local to the driver is ok, as long as they don't conflict
with anything possible used by their own fence implementation.
Christian.
> From an intel
> pov I don't care that much since we don't care about desktop prime, so
> if radeon/nouveau don't want to do that, meh. Imo the design as-is is
> fairly sound, and as simple as it can get given the requirements. I
> haven't heard an argument convincing me otherwise, so I guess we
> won't have prime support on linux that actually works, ever.
> -Daniel
next prev parent reply other threads:[~2014-07-22 15:35 UTC|newest]
Thread overview: 94+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-09 12:29 [PATCH 00/17] Convert TTM to the new fence interface Maarten Lankhorst
2014-07-09 12:29 ` [PATCH 01/17] drm/ttm: add interruptible parameter to ttm_eu_reserve_buffers Maarten Lankhorst
2014-07-09 12:29 ` [PATCH 02/17] drm/ttm: kill off some members to ttm_validate_buffer Maarten Lankhorst
2014-07-09 12:29 ` [PATCH 03/17] drm/nouveau: add reservation to nouveau_gem_ioctl_cpu_prep Maarten Lankhorst
2014-07-09 12:29 ` [PATCH 04/17] drm/nouveau: require reservations for nouveau_fence_sync and nouveau_bo_fence Maarten Lankhorst
2014-07-09 12:29 ` [PATCH 05/17] drm/ttm: call ttm_bo_wait while inside a reservation Maarten Lankhorst
2014-07-09 12:29 ` [PATCH 06/17] drm/ttm: kill fence_lock Maarten Lankhorst
2014-07-09 12:29 ` [PATCH 07/17] drm/nouveau: rework to new fence interface Maarten Lankhorst
2014-07-09 12:29 ` [PATCH 08/17] drm/radeon: add timeout argument to radeon_fence_wait_seq Maarten Lankhorst
2014-07-09 12:29 ` [PATCH 09/17] drm/radeon: use common fence implementation for fences Maarten Lankhorst
2014-07-09 12:57 ` Deucher, Alexander
2014-07-09 13:23 ` [PATCH v2 " Maarten Lankhorst
2014-07-10 17:27 ` Alex Deucher
2014-07-22 4:05 ` [PATCH " Dave Airlie
2014-07-22 8:43 ` Christian König
2014-07-22 11:46 ` Daniel Vetter
2014-07-22 11:52 ` Daniel Vetter
2014-07-22 11:57 ` Daniel Vetter
2014-07-22 12:19 ` Christian König
2014-07-22 13:26 ` [Nouveau] " Daniel Vetter
2014-07-22 13:45 ` Christian König
2014-07-22 14:44 ` Maarten Lankhorst
2014-07-22 15:02 ` Christian König
2014-07-22 15:18 ` Maarten Lankhorst
2014-07-22 15:17 ` Daniel Vetter
2014-07-22 15:35 ` Christian König [this message]
2014-07-22 15:42 ` Daniel Vetter
2014-07-22 15:59 ` Christian König
2014-07-22 16:21 ` Daniel Vetter
2014-07-22 16:39 ` Christian König
2014-07-22 16:52 ` Daniel Vetter
2014-07-22 16:43 ` Daniel Vetter
2014-07-23 6:40 ` Maarten Lankhorst
2014-07-23 6:52 ` Christian König
2014-07-23 7:02 ` Daniel Vetter
2014-07-23 7:06 ` Maarten Lankhorst
2014-07-23 7:09 ` Daniel Vetter
2014-07-23 7:15 ` Christian König
2014-07-23 7:32 ` Maarten Lankhorst
2014-07-23 7:41 ` Christian König
2014-07-23 7:26 ` Christian König
2014-07-23 7:31 ` Daniel Vetter
2014-07-23 7:37 ` Christian König
2014-07-23 7:51 ` Maarten Lankhorst
2014-07-23 7:58 ` Christian König
2014-07-23 8:07 ` Daniel Vetter
2014-07-23 8:20 ` Christian König
2014-07-23 8:25 ` Maarten Lankhorst
2014-07-23 8:42 ` Daniel Vetter
2014-07-23 8:46 ` Christian König
2014-07-23 8:54 ` Daniel Vetter
2014-07-23 9:27 ` Christian König
2014-07-23 9:30 ` Daniel Vetter
2014-07-23 9:36 ` Christian König
2014-07-23 9:38 ` Maarten Lankhorst
2014-07-23 9:39 ` Christian König
2014-07-23 9:39 ` Daniel Vetter
2014-07-23 9:44 ` Daniel Vetter
2014-07-23 9:47 ` Christian König
2014-07-23 9:52 ` Daniel Vetter
2014-07-23 9:55 ` Maarten Lankhorst
2014-07-23 10:13 ` Christian König
2014-07-23 10:52 ` Daniel Vetter
2014-07-23 12:36 ` Christian König
2014-07-23 12:42 ` Daniel Vetter
2014-07-23 13:16 ` Maarten Lankhorst
2014-07-23 14:05 ` Maarten Lankhorst
2014-07-24 13:47 ` Christian König
2014-07-23 8:01 ` Daniel Vetter
2014-07-23 8:31 ` Christian König
2014-07-23 12:35 ` Rob Clark
2014-07-22 14:05 ` Maarten Lankhorst
2014-07-22 14:24 ` Christian König
2014-07-22 14:27 ` Maarten Lankhorst
2014-07-22 14:39 ` Christian König
2014-07-22 14:47 ` Maarten Lankhorst
2014-07-22 15:16 ` Christian König
2014-07-22 15:19 ` Daniel Vetter
2014-07-22 15:42 ` Alex Deucher
2014-07-22 15:48 ` Daniel Vetter
2014-07-22 19:14 ` Jesse Barnes
2014-07-23 9:47 ` [Nouveau] " Daniel Vetter
2014-07-23 15:37 ` Jesse Barnes
2014-07-22 11:51 ` Maarten Lankhorst
2014-07-09 12:29 ` [PATCH 10/17] drm/qxl: rework to new fence interface Maarten Lankhorst
2014-07-09 12:30 ` [PATCH 11/17] drm/vmwgfx: get rid of different types of fence_flags entirely Maarten Lankhorst
2014-07-09 12:30 ` [PATCH 12/17] drm/vmwgfx: rework to new fence interface Maarten Lankhorst
2014-07-09 12:30 ` [PATCH 13/17] drm/ttm: flip the switch, and convert to dma_fence Maarten Lankhorst
2014-07-09 12:30 ` [PATCH 14/17] drm/nouveau: use rcu in nouveau_gem_ioctl_cpu_prep Maarten Lankhorst
2014-07-09 12:30 ` [PATCH 15/17] drm/radeon: use rcu waits in some ioctls Maarten Lankhorst
2014-07-09 12:30 ` [PATCH 16/17] drm/vmwgfx: use rcu in vmw_user_dmabuf_synccpu_grab Maarten Lankhorst
2014-07-09 12:30 ` [PATCH 17/17] drm/ttm: use rcu in core ttm Maarten Lankhorst
[not found] ` <CAHbf0-HaFi0px7QGfBErKenH7wDU08B5mxo_QhFJdDPC4WBDrQ@mail.gmail.com>
2014-07-09 13:21 ` [PATCH 00/17] Convert TTM to the new fence interface Maarten Lankhorst
2014-07-10 21:37 ` Thomas Hellström
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