> On Apr 18, 2018, at 14:55, mario.limonciello@xxxxxxxx wrote: > >> -----Original Message----- >> From: platform-driver-x86-owner@xxxxxxxxxxxxxxx [mailto:platform-driver-x86- >> owner@xxxxxxxxxxxxxxx] On Behalf Of David Zarzycki >> Sent: Tuesday, April 17, 2018 11:16 AM >> To: platform-driver-x86@xxxxxxxxxxxxxxx >> Subject: Dell Precision 7920 fan problems >> >> Hello, >> >> As a preface, my config: >> Dell Precision 7920 with two CPUs and the 1.4.1 BIOS. >> Red Hat Fedora 28 with their v4.16.1 kernel. > > 7920 Tower or rack? They're helpfully both called 7920. Hi Mario, Thanks for the helpful reply. I have the tower version. > >> >> I’m finding that the second CPU isn’t thermally managed. It seems to send about >> 1000 thermal distress interrupts/core/package/second under load and the second >> CPU throttles itself down to 1.7 GHz. If I force the fans to full speed via /sys, then >> the clock speed runs as expected (about 3.2 GHz). >> > > Which interface exactly are you using to increase fan speed? # "Processor Fan” echo 255 > /sys/devices/virtual/hwmon/hwmon0/pwm2 # "Motherboard Fan" echo 255 > /sys/devices/virtual/hwmon/hwmon0/pwm3 > > Assuming your platform supports it, I would recommend that you > keep --fan-speed configured to "auto" in DCC/CCTK or in BIOS setup. > Details on this option are here: > http://www.dell.com/support/manuals/us/en/19/command-configure-v3.3/dellcommandconfigure-cli-3.3/--fanspeed?guid=guid-8ec8603a-3691-48ac-ae70-f42d76eaa97c&lang=en-us > > I'm sorry I don't know off hand if your system should support it. I have always had the fan speed set to auto via the BIOS. >> Who is to blame here? Linux? Or the Dell BIOS? If the BIOS is to blame, how does >> one file bug reports against Dell? > > It's worth initially checking with 4.17-rc1. There are some fixes in ACPI around MLC code > that have resolved bugs that manifest in peculiar ways. > > Assuming that doesn't help I would doubt this particular mailing list (platform-x86) is the > right home for discussing it. I would recommend to file a kernel bug against ACPI to start. > If the ACPI experts conclude that there is likely a BIOS bug at play you can contact Dell > ProSupport to report it and they can bring it to the right people to look at in Dell. Thanks! Dave
