+Mike
On 5/9/2022 8:17 AM, Quan, Evan wrote:
[AMD Official Use Only - General]
*From:* amd-gfx <amd-gfx-bounces@xxxxxxxxxxxxxxxxxxxxx> *On Behalf Of
*Maxime Schmitt
*Sent:* Wednesday, April 6, 2022 1:40 AM
*To:* amd-gfx@xxxxxxxxxxxxxxxxxxxxx
*Subject:* [Question/Bug?] Why does the sysfs current_link_speed report
a different value than pp_dpm_pcie
Hello,
On my system the sysfs file "current_link_speed" is reporting "16.0 GT/s
PCIe".
The GPU has support for PCIe gen 4 (AMD Radeon RX 6800 XT).
However neither the CPU (AMD Ryzen 7 1700X) nor the motherboard have
support for PCIe gen 4.
The file "pp_dpm_pcie" returns the following:
0: 2.5GT/s, x1 310Mhz
1: 8.0GT/s, x16 619Mhz *
Which is correct.
Is this the expected behavior?
*/[Quan, Evan] “pp_dpm_pcie” is reporting the correct link speed. You
can trust that./*
*/While “current_link_speed” seems reporting the link speed the card is
capable of. Not sure whether that fits design./*
*/@Deucher, Alexander <mailto:Alexander.Deucher@xxxxxxx> Any comments
for the output of sysfs file “current_link_speed”?/*
In our architecture, GFX endpoint is not directly connected to
CPU/Chipset PCIE. We have upstream/downstream bridges in between
CPU/Chipset <-> || US Port <-> DS Port <-> GFX EP||
The actual speed will be reflected in the US port connected to the
CPU/chipset port or pp_dpm_pcie node as it shows the speed reported by
power management firmware.
Thanks,
Lijo
*//*
*/BR/*
*/Evan/*
I am asking because I recently added AMDGPU support to a monitoring tool
I maintain (nvtop) and I don't know where to get the information from.
Cheers,
Maxime
