From 48262cd9499c9cd0faf687ef9427cc0b0a3b0189 Mon Sep 17 00:00:00 2001
From: =?utf8?q?Christian=20K=C3=B6nig?= <christian.koenig@amd.com>
Date: Fri, 23 Mar 2018 16:33:57 +0100
Subject: [PATCH] drm/amdgpu: add checks if DMA-buf P2P is supported
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Check if we can do peer2peer on the PCIe bus.

Signed-off-by: Christian König <christian.koenig@amd.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Sumit Semwal <sumit.semwal@linaro.org>
Link: https://patchwork.freedesktop.org/patch/359294
---
 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 aef12ee..bbf6780 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
+++ 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;
+
 	if (attach->dev->driver == adev->dev->driver)
 		return 0;
 
-- 
2.7.4