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From: Christoph Hellwig <hch@infradead.org>
To: Alex Deucher <alexdeucher@gmail.com>
Cc: "moderated list:DMA BUFFER SHARING FRAMEWORK"
	<linaro-mm-sig@lists.linaro.org>,
	"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
	dri-devel <dri-devel@lists.freedesktop.org>,
	"Christoph Hellwig" <hch@infradead.org>,
	"Jerome Glisse" <jglisse@redhat.com>,
	"amd-gfx list" <amd-gfx@lists.freedesktop.org>,
	"Dan Williams" <dan.j.williams@intel.com>,
	"Logan Gunthorpe" <logang@deltatee.com>,
	"Christian König" <christian.koenig@amd.com>,
	"open list:DMA BUFFER SHARING FRAMEWORK"
	<linux-media@vger.kernel.org>
Subject: Re: [Linaro-mm-sig] [PATCH 4/8] dma-buf: add peer2peer flag
Date: Tue, 24 Apr 2018 23:41:18 -0700	[thread overview]
Message-ID: <20180425064118.GA28100@infradead.org> (raw)
In-Reply-To: <CADnq5_P3bT0TStSXpKh11ydifv=KwKtRj-7tDS=GQXey+8tBPw@mail.gmail.com>

On Wed, Apr 25, 2018 at 02:24:36AM -0400, Alex Deucher wrote:
> > It has a non-coherent transaction mode (which the chipset can opt to
> > not implement and still flush), to make sure the AGP horror show
> > doesn't happen again and GPU folks are happy with PCIe. That's at
> > least my understanding from digging around in amd the last time we had
> > coherency issues between intel and amd gpus. GPUs have some bits
> > somewhere (in the pagetables, or in the buffer object description
> > table created by userspace) to control that stuff.
> 
> Right.  We have a bit in the GPU page table entries that determines
> whether we snoop the CPU's cache or not.

I can see how that works with the GPU on the same SOC or SOC set as the
CPU.  But how is that going to work for a GPU that is a plain old PCIe
card?  The cache snooping in that case is happening in the PCIe root
complex.
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  reply	other threads:[~2018-04-25  6:41 UTC|newest]

Thread overview: 83+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-25 10:59 [PATCH 1/8] lib/scatterlist: add sg_set_dma_addr() helper Christian König
2018-03-25 10:59 ` [PATCH 4/8] dma-buf: add peer2peer flag Christian König
     [not found]   ` <20180325110000.2238-4-christian.koenig-5C7GfCeVMHo@public.gmane.org>
2018-03-29  6:57     ` Daniel Vetter
     [not found]       ` <20180329065753.GD3881-dv86pmgwkMBes7Z6vYuT8azUEOm+Xw19@public.gmane.org>
2018-03-29 11:34         ` Christian König
     [not found]           ` <8b823458-8bdc-3217-572b-509a28aae742-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2018-04-03  9:09             ` Daniel Vetter
     [not found]               ` <20180403090909.GN3881-dv86pmgwkMBes7Z6vYuT8azUEOm+Xw19@public.gmane.org>
2018-04-03 17:06                 ` Jerome Glisse
     [not found]                   ` <20180403170645.GB5935-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2018-04-03 18:08                     ` Daniel Vetter
2018-04-16 12:39                       ` Christoph Hellwig
     [not found]                         ` <20180416123937.GA9073-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2018-04-16 13:38                           ` Daniel Vetter
2018-04-19  8:16                             ` Christoph Hellwig
     [not found]                               ` <20180419081657.GA16735-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2018-04-20  7:13                                 ` Daniel Vetter
     [not found]                                   ` <20180420071312.GF31310-dv86pmgwkMBes7Z6vYuT8azUEOm+Xw19@public.gmane.org>
2018-04-20  8:58                                     ` Christian König
2018-04-20 10:17                                       ` Christoph Hellwig
     [not found]                                         ` <20180420101755.GA11400-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2018-04-20 10:44                                           ` Christian König
2018-04-20 12:46                                             ` Christoph Hellwig
2018-04-20 15:21                                               ` [Linaro-mm-sig] " Daniel Vetter
2018-04-24 18:48                                                 ` Christoph Hellwig
2018-04-24 19:32                                                   ` Daniel Vetter
2018-04-25  5:48                                                     ` Christoph Hellwig
     [not found]                                                       ` <20180425054855.GA17038-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2018-04-25  6:10                                                         ` Alex Deucher
2018-04-25  6:13                                                       ` Daniel Vetter
2018-04-25  6:23                                                         ` Daniel Vetter
2018-04-25  6:43                                                           ` Christoph Hellwig
     [not found]                                                             ` <20180425064335.GB28100-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2018-04-25  7:02                                                               ` Daniel Vetter
2018-04-25  7:09                                                                 ` Christoph Hellwig
     [not found]                                                                   ` <20180425070905.GA24827-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2018-04-25  7:30                                                                     ` Daniel Vetter
2018-04-25  7:56                                                                       ` Thierry Reding
2018-04-25  8:55                                                                         ` Christoph Hellwig
2018-04-25  7:43                                                                   ` Thierry Reding
2018-04-25  7:41                                                             ` Thierry Reding
2018-04-25  8:54                                                               ` noveau vs arm dma ops Christoph Hellwig
2018-04-25  9:25                                                                 ` Russell King - ARM Linux
2018-04-25 10:04                                                                 ` Daniel Vetter
2018-04-25 15:33                                                                   ` Christoph Hellwig
     [not found]                                                                     ` <20180425153312.GD27076-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2018-04-25 21:35                                                                       ` Daniel Vetter
2018-04-25 23:26                                                                         ` Russell King - ARM Linux
     [not found]                                                                           ` <20180425232646.GR16141-l+eeeJia6m9URfEZ8mYm6t73F7V6hmMc@public.gmane.org>
2018-04-26  9:17                                                                             ` Daniel Vetter
2018-04-26  9:09                                                                         ` Christoph Hellwig
     [not found]                                                                           ` <20180426090942.GA18811-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2018-04-26  9:45                                                                             ` Daniel Vetter
2018-04-26 11:12                                                                           ` Russell King - ARM Linux
2018-04-25 22:54                                                                     ` Russell King - ARM Linux
2018-04-26  9:13                                                                       ` Christoph Hellwig
2018-04-26  9:20                                                                       ` [Linaro-mm-sig] " Daniel Vetter
     [not found]                                                                         ` <CAKMK7uG9R6paoP4BmvqDVUP_4Db4Dz8MSXeLwUBMYaORa5-kVw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2018-04-26  9:24                                                                           ` Christoph Hellwig
2018-04-26  9:39                                                                             ` Daniel Vetter
     [not found]                                                         ` <CAKMK7uEFitkNQrD6cLX5Txe11XhVO=LC4YKJXH=VNdq+CY=DjQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2018-04-25  6:24                                                           ` [Linaro-mm-sig] [PATCH 4/8] dma-buf: add peer2peer flag Alex Deucher
2018-04-25  6:41                                                             ` Christoph Hellwig [this message]
     [not found]                                                               ` <20180425064118.GA28100-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2018-04-25 17:44                                                                 ` Alex Deucher
2018-04-25 18:38                                                                   ` Dan Williams
2018-05-04 12:45                                                                   ` Lucas Stach
     [not found] ` <20180325110000.2238-1-christian.koenig-5C7GfCeVMHo@public.gmane.org>
2018-03-25 10:59   ` [PATCH 2/8] PCI: Add pci_find_common_upstream_dev() Christian König
2018-03-28 12:38     ` Christoph Hellwig
     [not found]       ` <20180328123830.GB25060-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2018-03-28 15:07         ` Christian König
2018-03-28 15:47           ` Logan Gunthorpe
2018-03-28 16:02             ` Christian König
2018-03-28 16:25               ` Logan Gunthorpe
     [not found]                 ` <16c7bef8-5f03-9e89-1f50-b62fb139a36f-OTvnGxWRz7hWk0Htik3J/w@public.gmane.org>
2018-03-28 18:28                   ` Christian König
2018-03-28 18:57                     ` Logan Gunthorpe
     [not found]                       ` <e751cd28-f115-569f-5248-d24f30dee3cb-OTvnGxWRz7hWk0Htik3J/w@public.gmane.org>
2018-03-28 19:44                         ` Christian König
2018-03-28 19:53                           ` Logan Gunthorpe
2018-03-29 11:44                             ` Christian König
2018-03-29 15:45                               ` Logan Gunthorpe
     [not found]                                 ` <98ce6cfd-bcf3-811e-a0f1-757b60da467a-OTvnGxWRz7hWk0Htik3J/w@public.gmane.org>
2018-03-29 16:10                                   ` Christian König
2018-03-29 16:25                                     ` Logan Gunthorpe
2018-03-29 18:15                                       ` Christian König
2018-03-30  1:58                                       ` Jerome Glisse
2018-03-30  6:33                                         ` Christoph Hellwig
2018-03-30 15:25                                           ` Jerome Glisse
2018-03-30 18:46                                         ` Logan Gunthorpe
2018-03-30 19:45                                           ` Jerome Glisse
2018-04-02 17:02                                             ` Logan Gunthorpe
2018-04-02 17:20                                               ` Jerome Glisse
2018-04-02 17:37                                                 ` Logan Gunthorpe
2018-04-02 19:16                                                   ` Jerome Glisse
2018-04-02 19:32                                                     ` Logan Gunthorpe
2018-04-02 19:45                                                       ` Jerome Glisse
     [not found]                             ` <CADnq5_P-z=Noos_jaME9_CERri3C-m2hPPvx2bArr36O=1FnrA@mail.gmail.com>
2018-03-29 14:37                               ` Alex Deucher
2018-03-25 10:59   ` [PATCH 3/8] PCI: Add pci_peer_traffic_supported() Christian König
2018-03-25 10:59   ` [PATCH 5/8] drm/amdgpu: print DMA-buf status in debugfs Christian König
2018-03-25 10:59   ` [PATCH 6/8] drm/amdgpu: note that we can handle peer2peer DMA-buf Christian König
2018-03-25 10:59   ` [PATCH 7/8] drm/amdgpu: add amdgpu_gem_attach Christian König
2018-03-25 11:00   ` [PATCH 8/8] drm/amdgpu: add support for exporting VRAM using DMA-buf Christian König
2018-03-28 12:37 ` [PATCH 1/8] lib/scatterlist: add sg_set_dma_addr() helper Christoph Hellwig

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