Hi Mark, On 2022-04-29 21:25-0400, Mark Pearson wrote: > Hi Lyude > > On 4/29/22 17:14, Lyude Paul wrote: > > The new method of probing dual fan support introduced in: > > > > bf779aaf56ea ("platform/x86: thinkpad_acpi: Add dual fan probe") > > > > While this commit says this works on the X1 Carbon 9th Gen, it actually > > just results in hiding the second fan on my local machine. Additionally, > > I'm fairly sure this machine powers on quite often without either of the > > two fans spinning. > > > > So let's fix this by adding back the dual fan quirk for the X1 Carbon 9th > > Gen. > > > [..] > > I just double checked this on my X1C9 - and it's working correctly. 2nd > fan is detected correctly. > > I'd rather understand why it's not working on your setup then just > re-introduce the quirk. > > What happens on your system when the > res = fan2_get_speed(&speed); > is called? If that is failing it means your 2nd fan isn't responding and > that's not supposed to happen. Could you let me know if you get an error > code, if it happens every boot, etc > I assume when the function is called later it works successfully? I have the same issue. To me it looks like this: Probing for the second fan calls fan2_get_speed(), this calls fan_select_fan2() which in turn checks that tp_features.second_fan is set. But at this point in the tp_features.second_fan can not yet be set because it is either set from quirks or *after* the probing. Maybe some of the matches for the quirk TPACPI_FAN_2FAN should also have matched this device? It doesn't do so on my device. > Also please confirm which BIOS and EC version you have. Linux: 5.17.5 BIOS Revision: 1.51 Firmware Revision: 1.32 Thomas