Unsolved
This post is more than 5 years old
5 Posts
3
230458
Bios bug: Latitude 7440
Hi,
I've updated the laptop BIOS as soon as Dell released an update for my computer and I experienced how Dell makes wrong thing:
- From Bios A8 (factory BIOS in my case), the keyboard in Linux was broken but at least, the rest of the computer, mostly works. I was expecting a fix from Dell in this scenario so I was updating after each BIOS release until...
- ...In february, Dell released a new update with a fix for the keyboard in Linux (finally!) but... They introduced a new bug in CPU management (probably in PM states).
This bug consists, basically, when the laptop boots FROM battery (no charger or dock) the CPU does NOT scale correctly and by default is scaled to the minimum frequency, 700 Mhz. This happens on Linux as well as Windows 8.1 working on UEFI mode.
So I had to reboot the computer or even shutdown the laptop until the laptop wanted to boot correctly. Supposing that laptop booted correctly, It could also happen whether the computer was suspended by the OS or maybe closing the lip and as soon as the laptor was resumed, sometimes the CPU did not scale well fixing the CPU freq to the minimum. Apart of breaking the video output in pre-OS screen when your laptop is attached to dock or when you're using an external screen and lid is closed. This is annoying but I could deal with it..
- Now, after 3 months with the bugs previously explained, Dell has released a new version few days ago and the changelog prays:
-Fixed CPU may stay at low speed after resume from standby
-Fixed no display on external monitor when lid close in pre-boot/DOS mode
And my surprise is: THEY DID NOT FIX THE CPU PROBLEM. Come on Dell! I spent more than 1500€ in this laptop and it is almost useless, I can only work with it when it is docked like a desktop PC. Different colleges from my office chose the same laptop and we are suffering the same errors on Windows and Linux. I wrote this post because I am really angry after last BIOS update, I expected more from quality test team. I called to technical service and they told me it is a software problem, not a hardware, even a technician came to my office and he said that everything was ok with the laptop.
I hope a solution from you, almost 1 year with this laptop and there's not solution.
Cheers.
n13260
7 Posts
0
September 23rd, 2015 15:00
@Bimme
Are you successfully running intel_pstate driver now?
n13260
7 Posts
0
September 23rd, 2015 15:00
@Doug, thank you for your hint!
After switching to acpi-cpufreq driver CPU frequencies are not stuck any longer, under load they go up to ~2200GHz, as expected and as defined:
cat /sys/devices/system/cpu/cpu*/cpufreq/cpuinfo_max_freq
2201000
This is exactly the value shown in bios_limit. However, BIOS system information defines maximum clock speed with 2.200 GHz, not 2.201 GHz.
Using acpi-cpufreq driver and disabling SpeedStep in BIOS is now also working with the expected CPU frequency of 2.2 GHz.
Using intel_pstate driver CPU frequency remains stuck (independent whether thermald is running or stopped) bios_limit does not exist in this environment.
Doug Smythies
5 Posts
0
September 23rd, 2015 17:00
@N13260: I am aware of another person with your same issues. It might be kernel version dependent, because it didn't happen when he tried kernel 4.2. I have asked him to go back and try his original kernel, which was Ubuntu 3.16.0-28. I would like to understand your root issue, however I don't know that this is the place to do it.
EDIT: I made a mistake in kernel version, Fixed. The other person was not able to repeat their results with that kernel.
n13260
7 Posts
0
October 9th, 2015 00:00
@Doug,
I have tested with kernel 4.2 - same issue. Relocated this issue to:
en.community.dell.com/.../19655706
sabahang
5 Posts
0
November 12th, 2015 18:00
EXACT SAME PROBLEM! It took me ages to find the problem! Mine is a E7240 and my CPU frequency is stuck at 20% after resume from sleep. I bought the PC for about 1400 Euros! and I'm not happy to have to close all my running applications every time for a full restart to fix the issue! My Bios is the latest version? Is this a hardware issue?
Doug Smythies
5 Posts
0
November 14th, 2015 08:00
@sabahang: I do not think the root issue here is a hardware problem, but rather an incompatibility between the use of Clock Modulation and the intel_pstate CPU frequency scaling governor.
sabahang
5 Posts
0
November 15th, 2015 14:00
You might be right! I couldn't find a way to change frequency using native OS tools after a resume however I managed to tweak pstate using a software called ThrottleStop. I also upgraded my Bios to latest revision (rev16 I believe). Now when I resume the max freq is not so low anymore. it is around 60-70% percent whereas previously it was painfully around 25% and I couldn't change it. Whenever I hit the frequency limit and I can't seem to change it using High Performance power plan I use ThrottleStop to change it. Very useful app