Hi @daddle,
Modifying two PCIe bus-settings improves PCIe bus stability and prevents disconnection of the NVMe from the notebook’s NVMe port during intensive read/write!
By setting the ..
- the PCIe parameter ASPM to L1 (ASPM - Active-state power management) and
- the PCIe speed to Gen2 (5 GT/s), so by downgrading from the nb’s regular speed Gen3 (8 GT/s), ..
the notebook E14412 runs stably for days and the earlier obeyed issues do no longer occur:
- The NVMe no longer is disconnected during intensive read/write,
- the ‘RxErr’-messages no longer occur in the output of dmesg and
- the controller chip on the NVMe no longer warms up!
However the reduced speed ‘PCIe Gen2’ limits the notebook’s NVMe port data transfer rate to 0,87/0,85 GB/s (read/write). Previously, with ‘PCIe Gen3’, the transfer rate had been 1,7/1,6 GB/s (read/write). (Just to remind: Two lanes to m.2 slot for NVMe SSD (so width x2s) are implemented/available in this notebook, @daddle, acc. your earlier reply above.)
How were this changes implemented?
By adding the PCIe setting ‘pcie_aspm=off’ in the Linux configuration file ‘grub’ to the line
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash pcie_aspm=off"
the PCIe ASPM setting ends up with ‘ASPM L1’ for ..
- for the NVMe and its related notebook port, as well as
- for the Ethernet port and its related notebook port.
(Setting the notebook’s NVMe port to ‘ASPM Disabled’ did not succeed, no matter which other ASPM parameter I tried out in the configuration file grub. The notebook’s NVMe port always remained ‘ASPM L1’.)
To change PCIe speed to Gen2, I used the script of Alex Forencich ‘pcie_set_speed.sh’, which is easy to find on his webpage and in Linux forums. Here a quick example of changing the PCIe speed in 3 steps (the present notebook’s NVMe port is 0000:00:1d.0):
1) Confirmation of current speed (the nb’s regular speed) PCIe Gen3 (8 GT/s), upon booting, before changing:
fan_of@e14412:~$ sudo lspci -PPvv |grep --color -iE 'LnkSta: Speed [0-z]GT/s|00:1d.0|01:00.0'
00:1d.0 PCI bridge: Intel Corporation Comet Lake PCI Express Root Port #9 (rev f0) (prog-if 00 [Normal decode])
LnkSta: Speed 8GT/s, Width x2
00:1d.0/01:00.0 Non-Volatile memory controller: Sandisk Corp WD Blue SN570 NVMe SSD 1TB (prog-if 02 [NVM Express])
LnkSta: Speed 8GT/s, Width x2 (downgraded)
2) Setting PCIe speed to Gen2 by executing Alex’ script ‘pcie_set_speed.sh’:
fan_of@e14412:~$ sudo ./pcie_set_speed.sh 0000:00:1d.0 2
Link capabilities: 09724823
Max link speed: 3
Link status: 7023
Current link speed: 3
Configuring 0000:00:1d.0...
Original link control 2: 001e0003
Original link target speed: 3
New target link speed: 2
New link control 2: 001e0002
Triggering link retraining...
Original link control: 70230042
New link control: 70230062
Link status: 7022
Current link speed: 2
fan_of@e14412:~$
3) Confirmation of speed PCIe Gen2 (5GT/s) upon executing ‘pcie_set_speed.sh’:
fan_of@e14412:~$ sudo lspci -PPvv |grep --color -iE 'LnkSta: Speed [0-z]GT/s|00:1d.0|01:00.0'
00:1d.0 PCI bridge: Intel Corporation Comet Lake PCI Express Root Port #9 (rev f0) (prog-if 00 [Normal decode])
LnkSta: Speed 5GT/s, Width x2
00:1d.0/01:00.0 Non-Volatile memory controller: Sandisk Corp WD Blue SN570 NVMe SSD 1TB (prog-if 02 [NVM Express])
LnkSta: Speed 5GT/s (downgraded), Width x2 (downgraded)
Now, with PCIe Gen2 (5 GT/s), the notebook runs stably without the NVMe is disconnected during intensive read/write!
Yet, upon every start-up the notebook regularly runs at PCIe Gen3. Hence, every time the script needs to be applied again, in order to switch it to Gen2.
Open issue: Booting succeeds only if notebook starts in cool (pre-cooled) condition
Starting right away, the boot process regularly fails, indicating the NVMe is no longer connected to the PCIe bus. To successfully boot the notebook E14412, a prior cooling to 20 °C or less is required (i.e. by storing it in cool basement for 20 to 40 minutes). As soon as booting is completed, switching to PCIe Gen2 stabilises the notebook port’s connection to the NVMe, as mentioned above.
The notebook’s BIOS as originally implemented by the OEM does not offer any option for modifying the PCIe settings (i.e. starting up with PCIe Gen2), as far as I can see. So, I have no idea how to resolve this problem.
How to go forward?
- Any known typical issues, typical checks, typical modifications of the present notebook E14412’s hardware or BIOS, I could implement to get rid of the notebook’s NVMe port issues and the NVMe disconnection occurring when running at PCIe Gen3?
- Any hidden BIOS-options for modifying PCIe settings (i.e. boot at PCI Gen2) available?
Kindly I ask for your guidance and hints. How could I get a quick help for resolving?
Many thanks in advance!
Kind regards,
dgt.dabbler
(en-gb) ▼ 
Klick hier, um diese Seite auf Deutsch zu lesen
Click here to read this page in English
Cliquez ici pour lire cette page en français
Klik hier om deze pagina in het Nederlands te lezen
