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From: "Christian König" <ckoenig.leichtzumerken@gmail.com>
To: Jason Gunthorpe <jgg@ziepe.ca>
Cc: David1.Zhou@amd.com, Logan Gunthorpe <logang@deltatee.com>,
	intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
	hch@infradead.org, linaro-mm-sig@lists.linaro.org,
	linux-media@vger.kernel.org
Subject: Re: [Intel-gfx] [PATCH 4/6] drm/amdgpu: add checks if DMA-buf P2P is supported
Date: Wed, 11 Mar 2020 15:33:01 +0100	[thread overview]
Message-ID: <848c2f50-1529-f036-69cd-5104b7ebe27b@gmail.com> (raw)
In-Reply-To: <20200311140415.GB31668@ziepe.ca>

Am 11.03.20 um 15:04 schrieb Jason Gunthorpe:
> On Wed, Mar 11, 2020 at 02:51:56PM +0100, Christian König wrote:
>> Check if we can do peer2peer on the PCIe bus.
>>
>> Signed-off-by: Christian König <christian.koenig@amd.com>
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c | 4 ++++
>>   1 file changed, 4 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
>> index aef12ee2f1e3..bbf67800c8a6 100644
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
>> @@ -38,6 +38,7 @@
>>   #include <drm/amdgpu_drm.h>
>>   #include <linux/dma-buf.h>
>>   #include <linux/dma-fence-array.h>
>> +#include <linux/pci-p2pdma.h>
>>   
>>   /**
>>    * amdgpu_gem_prime_vmap - &dma_buf_ops.vmap implementation
>> @@ -179,6 +180,9 @@ static int amdgpu_dma_buf_attach(struct dma_buf *dmabuf,
>>   	struct amdgpu_device *adev = amdgpu_ttm_adev(bo->tbo.bdev);
>>   	int r;
>>   
>> +	if (pci_p2pdma_distance_many(adev->pdev, &attach->dev, 1, true) < 0)
>> +		attach->peer2peer = false;
>> +
> Are there other related patches than this series?
>
> p2p dma mapping needs to be done in common code, in p2pdma.c - ie this
> open coding is missing the bus_offset stuff, at least.

Yeah, I'm aware of this. But I couldn't find a better way for now.

> I really do not want to see drivers open code this stuff.
>
> We already have a p2pdma API for handling the struct page case, so I
> suggest adding some new p2pdma API to handle this for non-struct page
> cases.
>
> ie some thing like:
>
> int 'p2pdma map bar'(
>     struct pci_device *source,
>     unsigned int source_bar_number,
>     struct pci_device *dest,
>     physaddr&len *array_of_offsets & length pairs into source bar,
>     struct scatterlist *output_sgl)

Well that's exactly what I have to avoid since I don't have the array of 
offsets around and want to avoid constructing it.

Similar problem for dma_map_resource(). My example does this on demand, 
but essentially we also have use cases where this is done only once.

Ideally we would have some function to create an sgl based on some 
arbitrary collection of offsets and length inside a BAR.

Regards,
Christian.

>
> Jason

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  parent reply	other threads:[~2020-03-11 15:04 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-11 13:51 [Intel-gfx] P2P for DMA-buf Christian König
2020-03-11 13:51 ` [Intel-gfx] [PATCH 1/6] lib/scatterlist: add sg_set_dma_addr() function Christian König
2020-03-11 15:28   ` Christoph Hellwig
2020-03-12 10:14     ` Christian König
2020-03-12 10:19       ` Christoph Hellwig
2020-03-12 10:31         ` Christian König
2020-03-12 10:47           ` Christoph Hellwig
2020-03-12 11:02             ` Christian König
     [not found]             ` <20200312141928.GK31668@ziepe.ca>
2020-03-12 15:39               ` Christian König
2020-03-12 16:13               ` Logan Gunthorpe
2020-03-13 11:21               ` Christoph Hellwig
2020-03-13 13:33                 ` Christian König
     [not found]                 ` <20200313121742.GZ31668@ziepe.ca>
2020-03-16  8:56                   ` Christoph Hellwig
2020-03-16  9:41                     ` Christian König
2020-03-16  9:52                       ` Christoph Hellwig
2020-03-11 13:51 ` [Intel-gfx] [PATCH 2/6] dma-buf: add peer2peer flag Christian König
2020-03-11 13:51 ` [Intel-gfx] [PATCH 3/6] drm/amdgpu: note that we can handle peer2peer DMA-buf Christian König
2020-03-11 13:51 ` [Intel-gfx] [PATCH 4/6] drm/amdgpu: add checks if DMA-buf P2P is supported Christian König
     [not found]   ` <20200311140415.GB31668@ziepe.ca>
2020-03-11 14:33     ` Christian König [this message]
     [not found]       ` <20200311143835.GD31668@ziepe.ca>
2020-03-11 14:43         ` Christian König
2020-03-11 13:51 ` [Intel-gfx] [PATCH 5/6] drm/amdgpu: add support for exporting VRAM using DMA-buf v2 Christian König
2020-03-11 15:08   ` Alex Deucher
2020-03-11 13:51 ` [Intel-gfx] [PATCH 6/6] drm/amdgpu: improve amdgpu_gem_info debugfs file Christian König
2020-03-11 18:09 ` [Intel-gfx] ✗ Fi.CI.CHECKPATCH: warning for series starting with [1/6] lib/scatterlist: add sg_set_dma_addr() function Patchwork
2020-03-11 18:34 ` [Intel-gfx] ✗ Fi.CI.BAT: failure " Patchwork

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