Intel Arc A770 PCIe - Speed 2.5GT/s, Width x1

[pioto]

Hi Intel,

lspci reports PCIe 1.0/x1 for the GPU (56a0) and bridge downstream port (4fa4). The upstream port reports the bandwidth correctly at PCIe4.0/16.

I am running Arc A770 on Ubuntu 22.04 with kernel 5.17.0-1020-oem with all recommended Intel drivers + linux-firmware.git copied over /lib/firmware. Without copying linux-firmware, the system hangs on boot in text mode. I have seen similar tickets about PCIe 1.0/x1, but I decided to raise this one to stress that the bug reproduces for supported installations too.

I suspect a card  firmware issue here so I am not sure about my step of copying over latest linux-firmware.git, If I do not then Ubuntu 22.04 + Arc 770 will not boot into GUI mode.

On the bright the desktop is rendering correctly and is fast, so I am pretty satisfied. I reckon the card is actually running in PCIe 4.0/16 mode and the issue is with reporting only (quick OpenCL experiments show 17-18GB/s bandwidth over PCIe).

Many thanks.

Piotr

[Jean_Intel]

Hello pioto123,

We hope you are doing fine.

We have not heard back from you. So we will close this thread. If you need any additional information, submit a new question, as this thread will no longer be monitored.

Best regards.

Jean O. 

Intel Customer Support Technician.

[SteveTech]

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@pioto wrote:

On the bright the desktop is rendering correctly and is fast, so I am pretty satisfied. I reckon the card is actually running in PCIe 4.0/16 mode and the issue is with reporting only (quick OpenCL experiments show 17-18GB/s bandwidth over PCIe).

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I found the same issue with it reporting x1, and did a similar experiment with the 'Memory Bandwidth' benchmark in xpu-smi:

xpu-smi diag -d 0 --singletest 5

In my case, it said it failed (pretty sure it's fine though) but still reported 11.108 GBPS which makes sense for PCIe 3.0 x16 + overhead (which is correct).

Just wanted to add the benchmark for other people's piece of mind.

Thanks,
Steve