Hi, after the $subject patch I get lots of errors like this: [ 120.378614] applesmc: send_byte(0x00, 0x0300) fail: 0x40 [ 120.378621] applesmc: LKSB: write data fail [ 120.512782] applesmc: send_byte(0x00, 0x0300) fail: 0x40 [ 120.512787] applesmc: LKSB: write data fail CPU sticks at low speed and no fan is turning on. Reverting this patch on top of 5.9-rc6 solves this problem. Some information from dmidecode: Base Board Information Manufacturer: Apple Inc. Product Name: Mac-7DF21CB3ED6977E5 Version: MacBookAir6,2 Handle 0x0020, DMI type 11, 5 bytes OEM Strings String 1: Apple ROM Version. Model: …, Handle 0x0020, DMI type 11, 5 bytes OEM Strings String 1: Apple ROM Version. Model: MBA61. EFI Version: 122.0.0 String 2: .0.0. Built by: root@saumon. Date: Wed Jun 10 18: String 3: 10:36 PDT 2020. Revision: 122 (B&I). ROM Version: F000_B String 4: 00. Build Type: Official Build, Release. Compiler: Appl String 5: e clang version 3.0 (tags/Apple/clang-211.10.1) (based on LLVM String 6: 3.0svn). Writing to things in /sys/devices/platform/applesmc.768 gives also the said errors. But writing 1 to fan1_maunal and 5000 to fan1_output turns the fan on despite error messages. Config used is: https://misc.andi.de1.cc/mac-config.gz Regards, Andreas