RE: Issue about PCI physical slot fetch incorrect number

[<Erin_Tsao@wistron.com>]

Hi Martin,
Thanks for helping me forwarding the mail.
Hope to have good news from them.

Wish you have a good day!

BR,
Erin

-----Original Message-----
From: Martin Mareš <mj@ucw.cz> 
Sent: Saturday, August 24, 2024 2:52 AM
To: Erin Tsao/WHQ/Wistron <Erin_Tsao@wistron.com>
Cc: Linux-PCI Mailing List <linux-pci@vger.kernel.org>
Subject: Re: Issue about PCI physical slot fetch incorrect number

Hi!

> This is Erin from Taiwan. I have a question about physical slot number.
> Currently we are working on the PCIE slot number assigning by PCIE switch. In the PCIe slot assignment process, the slot numbers are assigned to bridges first, and then the end devices fetch the slot ID from the bridge in the upper layer.
> 
> I have observed that under our PCIE switch, GPUs will create a bridge before reaching the end device. If GPUs also fetch the slot ID from the upper bridge layer, they may retrieve incorrect values.
> 
> Our GPU will get the physical slot number with number “0”, and show the slot number “0”、”0-1” , etc.
> May I ask
> 
>   1.  Why GPU will fetch the slot number “0”? Is the slot number assigned to GPU related to any register? Or can we set any bit to fetch the right number?
>   2.  Is there any possible for us not to show the physical slot number of GPU?
> 
> I have checked with the code on the git, unfortunately I didn’t obtain any answer.
> It will really be helpful to get the response from you.
> Hope to hear from you soon, thanks in advance.

It's a long long time since I was the maintainer of the PCI layer in the kernel. Now I maintain just the PCI utilities which display whatever the kernel tells them.

I am forwarding your question to the linux-pci mailing list where it hopefully finds a better audience.

				Martin

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