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From: Andrey Grodzovsky <Andrey.Grodzovsky@amd.com>
To: Daniel Vetter <daniel@ffwll.ch>
Cc: "Rob Herring" <robh@kernel.org>,
	"Greg KH" <gregkh@linuxfoundation.org>,
	dri-devel <dri-devel@lists.freedesktop.org>,
	"Anholt, Eric" <eric@anholt.net>,
	"Pekka Paalanen" <ppaalanen@gmail.com>,
	"amd-gfx list" <amd-gfx@lists.freedesktop.org>,
	"Alex Deucher" <Alexander.Deucher@amd.com>,
	"Lucas Stach" <l.stach@pengutronix.de>,
	"Wentland, Harry" <Harry.Wentland@amd.com>,
	"Christian König" <christian.koenig@amd.com>,
	"Qiang Yu" <yuq825@gmail.com>
Subject: Re: [PATCH v3 05/12] drm/ttm: Expose ttm_tt_unpopulate for driver use
Date: Mon, 4 Jan 2021 11:33:24 -0500	[thread overview]
Message-ID: <b20b7304-85ba-45ae-d801-78461cc96e1d@amd.com> (raw)
In-Reply-To: <5feff301-0aca-3e07-c1c4-31e4a91fc942@amd.com>


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Hey Daniel, back from vacation and going over our last long thread i think you 
didn't reply
to my last question bellow (Or at least I can't find it).

Andrey

On 12/17/20 4:13 PM, Andrey Grodzovsky wrote:
>>> Ok, so I assumed that with vmap_local you were trying to solve the problem of
>>> quick reinsertion
>>> of another device into same MMIO range that my driver still points too but
>>> actually are you trying to solve
>>> the issue of exported dma buffers outliving the device ? For this we have
>>> drm_device refcount in the GEM layer
>>> i think.
>> That's completely different lifetime problems. Don't mix them up :-)
>> One problem is the hardware disappearing, and for that we _have_ to
>> guarantee timeliness, or otherwise the pci subsystem gets pissed
>> (since like you say, a new device might show up and need it's mmio
>> bars assigned to io ranges). The other is lifetim of the software
>> objects we use as interfaces, both from userspace and from other
>> kernel drivers. There we fundamentally can't enforce timely cleanup,
>> and have to resort to refcounting.
>
>
> So regarding the second issue, as I mentioned above, don't we already use 
> drm_dev_get/put
> for exported BOs ? Earlier in this discussion you mentioned that we are ok for 
> dma buffers since
> we already have the refcounting at the GEM layer and the real life cycle 
> problem we have is the dma_fences
> for which there is no drm_dev refcounting. Seems to me then that vmap_local is 
> superfluous because
> of the recounting we already have for exported dma_bufs and for dma_fences it 
> won't help.
>
> Andrey 

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  reply	other threads:[~2021-01-04 16:33 UTC|newest]

Thread overview: 105+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-21  5:21 [PATCH v3 00/12] RFC Support hot device unplug in amdgpu Andrey Grodzovsky
2020-11-21  5:21 ` [PATCH v3 01/12] drm: Add dummy page per device or GEM object Andrey Grodzovsky
2020-11-21 14:15   ` Christian König
2020-11-23  4:54     ` Andrey Grodzovsky
2020-11-23  8:01       ` Christian König
2021-01-05 21:04         ` Andrey Grodzovsky
2021-01-07 16:21           ` Daniel Vetter
2021-01-07 16:26             ` Andrey Grodzovsky
2021-01-07 16:28               ` Andrey Grodzovsky
2021-01-07 16:30               ` Daniel Vetter
2021-01-07 16:37                 ` Andrey Grodzovsky
2021-01-08 14:26                   ` Andrey Grodzovsky
2021-01-08 14:33                     ` Christian König
2021-01-08 14:46                       ` Andrey Grodzovsky
2021-01-08 14:52                         ` Christian König
2021-01-08 16:49                           ` Grodzovsky, Andrey
2021-01-11 16:13                             ` Daniel Vetter
2021-01-11 16:15                               ` Daniel Vetter
2021-01-11 17:41                                 ` Andrey Grodzovsky
2021-01-11 20:45                                 ` Andrey Grodzovsky
2021-01-12  9:10                                   ` Daniel Vetter
2021-01-12 12:32                                     ` Christian König
2021-01-12 15:59                                       ` Andrey Grodzovsky
2021-01-13  9:14                                         ` Christian König
2021-01-13 14:40                                           ` Andrey Grodzovsky
2021-01-12 15:54                                     ` Andrey Grodzovsky
2021-01-12  8:12                               ` Christian König
2021-01-12  9:13                                 ` Daniel Vetter
2020-11-21  5:21 ` [PATCH v3 02/12] drm: Unamp the entire device address space on device unplug Andrey Grodzovsky
2020-11-21 14:16   ` Christian König
2020-11-24 14:44     ` Daniel Vetter
2020-11-21  5:21 ` [PATCH v3 03/12] drm/ttm: Remap all page faults to per process dummy page Andrey Grodzovsky
2020-11-21  5:21 ` [PATCH v3 04/12] drm/ttm: Set dma addr to null after freee Andrey Grodzovsky
2020-11-21 14:13   ` Christian König
2020-11-23  5:15     ` Andrey Grodzovsky
2020-11-23  8:04       ` Christian König
2020-11-21  5:21 ` [PATCH v3 05/12] drm/ttm: Expose ttm_tt_unpopulate for driver use Andrey Grodzovsky
2020-11-25 10:42   ` Christian König
2020-11-23 20:05     ` Andrey Grodzovsky
2020-11-23 20:20       ` Christian König
2020-11-23 20:38         ` Andrey Grodzovsky
2020-11-23 20:41           ` Christian König
2020-11-23 21:08             ` Andrey Grodzovsky
2020-11-24  7:41               ` Christian König
2020-11-24 16:22                 ` Andrey Grodzovsky
2020-11-24 16:44                   ` Christian König
2020-11-25 10:40                     ` Daniel Vetter
2020-11-25 12:57                       ` Christian König
2020-11-25 16:36                         ` Daniel Vetter
2020-11-25 19:34                           ` Andrey Grodzovsky
2020-11-27 13:10                             ` Grodzovsky, Andrey
2020-11-27 14:59                             ` Daniel Vetter
2020-11-27 16:04                               ` Andrey Grodzovsky
2020-11-30 14:15                                 ` Daniel Vetter
2020-11-25 16:56                         ` Michel Dänzer
2020-11-25 17:02                           ` Daniel Vetter
2020-12-15 20:18                     ` Andrey Grodzovsky
2020-12-16  8:04                       ` Christian König
2020-12-16 14:21                         ` Daniel Vetter
2020-12-16 16:13                           ` Andrey Grodzovsky
2020-12-16 16:18                             ` Christian König
2020-12-16 17:12                               ` Daniel Vetter
2020-12-16 17:20                                 ` Daniel Vetter
2020-12-16 18:26                                 ` Andrey Grodzovsky
2020-12-16 23:15                                   ` Daniel Vetter
2020-12-17  0:20                                     ` Andrey Grodzovsky
2020-12-17 12:01                                       ` Daniel Vetter
2020-12-17 19:19                                         ` Andrey Grodzovsky
2020-12-17 20:10                                           ` Christian König
2020-12-17 20:38                                             ` Andrey Grodzovsky
2020-12-17 20:48                                               ` Daniel Vetter
2020-12-17 21:06                                                 ` Andrey Grodzovsky
2020-12-18 14:30                                                   ` Daniel Vetter
2020-12-17 20:42                                           ` Daniel Vetter
2020-12-17 21:13                                             ` Andrey Grodzovsky
2021-01-04 16:33                                               ` Andrey Grodzovsky [this message]
2020-11-21  5:21 ` [PATCH v3 06/12] drm/sched: Cancel and flush all oustatdning jobs before finish Andrey Grodzovsky
2020-11-22 11:56   ` Christian König
2020-11-21  5:21 ` [PATCH v3 07/12] drm/sched: Prevent any job recoveries after device is unplugged Andrey Grodzovsky
2020-11-22 11:57   ` Christian König
2020-11-23  5:37     ` Andrey Grodzovsky
2020-11-23  8:06       ` Christian König
2020-11-24  1:12         ` Luben Tuikov
2020-11-24  7:50           ` Christian König
2020-11-24 17:11             ` Luben Tuikov
2020-11-24 17:17               ` Andrey Grodzovsky
2020-11-24 17:41                 ` Luben Tuikov
2020-11-24 17:40               ` Christian König
2020-11-24 17:44                 ` Luben Tuikov
2020-11-21  5:21 ` [PATCH v3 08/12] drm/amdgpu: Split amdgpu_device_fini into early and late Andrey Grodzovsky
2020-11-24 14:53   ` Daniel Vetter
2020-11-24 15:51     ` Andrey Grodzovsky
2020-11-25 10:41       ` Daniel Vetter
2020-11-25 17:41         ` Andrey Grodzovsky
2020-11-21  5:21 ` [PATCH v3 09/12] drm/amdgpu: Add early fini callback Andrey Grodzovsky
2020-11-21  5:21 ` [PATCH v3 10/12] drm/amdgpu: Avoid sysfs dirs removal post device unplug Andrey Grodzovsky
2020-11-24 14:49   ` Daniel Vetter
2020-11-24 22:27     ` Andrey Grodzovsky
2020-11-25  9:04       ` Daniel Vetter
2020-11-25 17:39         ` Andrey Grodzovsky
2020-11-27 13:12           ` Grodzovsky, Andrey
2020-11-27 15:04           ` Daniel Vetter
2020-11-27 15:34             ` Andrey Grodzovsky
2020-11-21  5:21 ` [PATCH v3 11/12] drm/amdgpu: Register IOMMU topology notifier per device Andrey Grodzovsky
2020-11-21  5:21 ` [PATCH v3 12/12] drm/amdgpu: Fix a bunch of sdma code crash post device unplug Andrey Grodzovsky

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