Arch Linux

zegranix

Member

Registered: 2020-08-19

Posts: 1

Kernel 5.8.1-arch1-1, can't write data to applesmc error after upgrade

Hello,

Hardware:  MacBookPro 6,1 mid-2010. Using latest version of mbpfan
(mbpfan-git-2.2.1.r4.g52d8973-1-x86_64) from AUR. Have used mbpfan for long
time on Arch across many upgrades with no problems.

After recent upgrade to 5.8.1-arch1-1 kernel, from 5.7.12, mbpfan does not work,
with error

ehost mbpfan[374]: Could not set fan speed: Input/output error
Aug 18 21:01:21 ehost kernel: applesmc: send_byte(0x40, 0x0300) fail: 0x00
Aug 18 21:01:21 ehost kernel: applesmc: F1Tg: write data fail

From looking in /sys/devices/platform/applesmc.768

one can see that even root can only write to fan1_manual, fan1_min, and
fan1_output, for example.

-r--r--r-- 1 root root 4096 Aug 18 21:00 fan1_input
-r--r--r-- 1 root root 4096 Aug 18 21:01 fan1_label
-rw-r--r-- 1 root root 4096 Aug 18 21:00 fan1_manual
-r--r--r-- 1 root root 4096 Aug 18 21:00 fan1_max
-rw-r--r-- 1 root root 4096 Aug 18 21:00 fan1_min
-rw-r--r-- 1 root root 4096 Aug 18 21:00 fan1_output

The above permissions have not changed from earlier kernels when mbpfan worked.
They are exactly the same on the systems where mbpfan works.

As a test, I upgraded another system with a working mbpfan (kernel 5.7.9) to 5.8.1, and
the same no write problem appears.

--It seems that something in the kernel that affects mbpfan may have changed between
5.7.12 and 5.8.1. 

--Ideas?

ahesford

Member

Registered: 2019-03-14

Posts: 3

Re: Kernel 5.8.1-arch1-1, can't write data to applesmc error after upgrade

I'm seeing the same "Could not set fan speed: Input/output error" on Void Linux with kernels >= 5.8.1 and am interested in seeing a resolution. For me, fan control seems to be working despite the error messages. The mbpfan daemon still adjusts the speeds dynamically (with these messages appearing on the console with every change) and I can manually cat text to `/sys/devices/platform/applesmc.768/fan1_output` to force adjustments (but, again, with the error message).

dilyn

Member

From: Lansing, MI

Registered: 2014-07-16

Posts: 11

Re: Kernel 5.8.1-arch1-1, can't write data to applesmc error after upgrade

I've been having a similar issue with applesmc for about as long as you. I haven't been able to find anything about this problem anywhere.
There is mention in dmesg about some portion of the module using deprecated something or other (been a long time since I've taken a peek), but I don't think that would be the cause of this problem.

mbpfan seems to work... Fine... My computer hasn't melted, at least.

Last edited by dilyn (2020-09-08 03:56:21)

smallberries.john

Member

Registered: 2020-11-19

Posts: 5

Re: Kernel 5.8.1-arch1-1, can't write data to applesmc error after upgrade

The last kernel that I know that fan control worked with is 5.6.14. This is what I'm using on my MBP. Here's what I get in dmesg after I boot:

[   10.488060] input: applesmc as /devices/platform/applesmc.768/input/input15
[   10.488371] applesmc applesmc.768: hwmon_device_register() is deprecated. Please convert the driver to use hwmon_device_register_with_info()

My guess is that the driver hasn't been converted. I can't see any indication on github that the applesmc.c source hasn't been changed in 10 years. Your only option seems to be to downgrade if you want granular control over your fan.

Last edited by smallberries.john (2020-11-19 00:58:51)

loqs

Member

Registered: 2014-03-06

Posts: 17,372

Re: Kernel 5.8.1-arch1-1, can't write data to applesmc error after upgrade

My guess is that the driver hasn't been converted. I can't see any indication on github that the applesmc.c source hasn't been changed in 10 years.

Does https://github.com/torvalds/linux/commi … ae91b2b40b which fixes https://github.com/torvalds/linux/commi … e1c8e80ebb resolve the issue?
Where were you looking on github for 10 years without updates to applesmc.c?