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Message-ID: <9ff1a7ef-a5a4-dd80-6f19-304b668d82a1@amd.com>
Date: Tue, 22 Jun 2021 17:31:12 +0200
From: Christian König <christian.koenig@....com>
To: Jason Gunthorpe <jgg@...pe.ca>
Cc: Oded Gabbay <oded.gabbay@...il.com>,
Christian König <ckoenig.leichtzumerken@...il.com>,
Gal Pressman <galpress@...zon.com>, sleybo@...zon.com,
linux-rdma <linux-rdma@...r.kernel.org>,
Oded Gabbay <ogabbay@...nel.org>,
Christoph Hellwig <hch@....de>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
dri-devel <dri-devel@...ts.freedesktop.org>,
"moderated list:DMA BUFFER SHARING FRAMEWORK"
<linaro-mm-sig@...ts.linaro.org>,
Doug Ledford <dledford@...hat.com>,
Tomer Tayar <ttayar@...ana.ai>,
amd-gfx list <amd-gfx@...ts.freedesktop.org>,
Greg KH <gregkh@...uxfoundation.org>,
Alex Deucher <alexander.deucher@....com>,
Leon Romanovsky <leonro@...dia.com>,
"open list:DMA BUFFER SHARING FRAMEWORK"
<linux-media@...r.kernel.org>
Subject: Re: [Linaro-mm-sig] [PATCH v3 1/2] habanalabs: define uAPI to export
FD for DMA-BUF
Am 22.06.21 um 17:28 schrieb Jason Gunthorpe:
> On Tue, Jun 22, 2021 at 05:24:08PM +0200, Christian König wrote:
>
>>>> I will take two GAUDI devices and use one as an exporter and one as an
>>>> importer. I want to see that the solution works end-to-end, with real
>>>> device DMA from importer to exporter.
>>> I can tell you it doesn't. Stuffing physical addresses directly into
>>> the sg list doesn't involve any of the IOMMU code so any configuration
>>> that requires IOMMU page table setup will not work.
>> Sure it does. See amdgpu_vram_mgr_alloc_sgt:
>>
>> amdgpu_res_first(res, offset, length, &cursor);
> ^^^^^^^^^^
>
> I'm not talking about the AMD driver, I'm talking about this patch.
>
> + bar_address = hdev->dram_pci_bar_start +
> + (pages[cur_page] - prop->dram_base_address);
> + sg_dma_address(sg) = bar_address;
Yeah, that is indeed not working.
Oded you need to use dma_map_resource() for this.
Christian.
>
> Jason
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