On 1/27/19 1:59 PM, Chris Siebenmann wrote:
I have an Asus PRIME Z370-A motherboard, on which I run Fedora. In Fedora's 4.19.15 kernel, the nct6775 driver detected all six fan sensors on my motherboard. In their recently released 4.20.3 kernel, it only detects five, dropping the sixth fan sensor (which happens to be the second chassis fan on this motherboard). I filed a Fedora bug report, and after discussions with the Fedora maintainer for this area we think we have narrowed the likely issue down to this change: hwmon: (nct6775) Separate fan/pwm configuration detection for NCT6793D https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=2d99925a15b639026b67bd96419df6f9d760b212 If I'm reading the before and after code right, the code before the change did: fan6pin = !dsw_en && (cr2d & BIT(1)); fan6pin |= creb & BIT(3); And the code after dropped the '!dsw_en' part and became just: fan6pin = creb & BIT(3);
Sigh. Too much complexity in those chips. Yes, the first line got lost, but it applies for NCT6793D. Sorry for that. I'll write a patch.
(I don't know if it's possible for me to probe things in some way to see if dsw_en would be set, or even dump the full raw state of these registers.) The full Fedora bug report is here, with various things like dmesg output and so on from the two kernels on my hardware: https://bugzilla.redhat.com/show_bug.cgi?id=1669564 (Hopefully emailing you directly instead of the linux-hwmon mailing list is the right choice. I looked at the mailing list archive and it seemed to be for development, with lots of patches, instead of issue reports.)
e-mailing me, or any other maintainer, directly without copying the respective mailing list is never the correct choice. It is ok to copy me, but it is never ok to not let the rest of the community know that there may be a problem. Guenter
