[PATCH v3] drm/amdgpu: Inform if PCIe based P2P links are not available

[PATCH v3] drm/amdgpu: Inform if PCIe based P2P links are not available

[Ramesh Errabolu]

Raise an info message in kernel log if PCIe root complex
determines that a AMD GPU device D<i> cannot have P2P
communication with another AMD GPU device D<j>

Signed-off-by: Ramesh Errabolu <Ramesh.Errabolu@amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
index 230c24638a34..76182d5c719d 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
@@ -6222,6 +6222,9 @@ bool amdgpu_device_is_peer_accessible(struct amdgpu_device *adev,
 	bool p2p_access =
 		!adev->gmc.xgmi.connected_to_cpu &&
 		!(pci_p2pdma_distance(adev->pdev, peer_adev->dev, false) < 0);
+	if (!p2p_access)
+		dev_info(adev->dev, "has no link with Peer device: %s\n",
+			pci_name(peer_adev->pdev));
 
 	bool is_large_bar = adev->gmc.visible_vram_size &&
 		adev->gmc.real_vram_size == adev->gmc.visible_vram_size;
-- 
2.34.1

Re: [PATCH v3] drm/amdgpu: Inform if PCIe based P2P links are not available

[Felix Kuehling]

On 2024-11-06 17:54, Ramesh Errabolu wrote:
> Raise an info message in kernel log if PCIe root complex
> determines that a AMD GPU device D<i> cannot have P2P
> communication with another AMD GPU device D<j>
> 
> Signed-off-by: Ramesh Errabolu <Ramesh.Errabolu@amd.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> index 230c24638a34..76182d5c719d 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> @@ -6222,6 +6222,9 @@ bool amdgpu_device_is_peer_accessible(struct amdgpu_device *adev,
>  	bool p2p_access =
>  		!adev->gmc.xgmi.connected_to_cpu &&
>  		!(pci_p2pdma_distance(adev->pdev, peer_adev->dev, false) < 0);
> +	if (!p2p_access)
> +		dev_info(adev->dev, "has no link with Peer device: %s\n",
> +			pci_name(peer_adev->pdev));

Please clarify the message to say "PCIe P2P access from peer device %s is not supported by the chipset". And "peer" should not be capitalized. With that fixed, the patch is

Reviewed-by: Felix Kuehling <felix.kuehling@amd.com>

>  
>  	bool is_large_bar = adev->gmc.visible_vram_size &&
>  		adev->gmc.real_vram_size == adev->gmc.visible_vram_size;