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#1 2017-06-20 12:58:48

zuwarm
Member
Registered: 2017-06-20
Posts: 7

i801 i2c-dev not working

Hi,

I have problems accessing i2c on my (pretty old) hardware. I do see devices like /dev/i2c-X, however these seem to be for video. What I'm looking for is an i2c SMBus with i801 module I can access.

Here is what I did:

$ modprobe i2c-dev
$ i2cdetect -l
i2c-3   i2c             i915 gmbus dpc                          I2C adapter
i2c-1   i2c             i915 gmbus vga                          I2C adapter
i2c-4   i2c             i915 gmbus dpb                          I2C adapter
i2c-2   i2c             i915 gmbus panel                        I2C adapter
i2c-0   i2c             i915 gmbus ssc                          I2C adapter
i2c-5   i2c             i915 gmbus dpd                          I2C adapter

$ lsmod |grep i2c
i2c_i801               24576  0
i2c_dev                16384  0
i2c_algo_bit           16384  1 i915

$ lspci
...
00:1f.3 SMBus: Intel Corporation 82801H (ICH8 Family) SMBus Controller (rev 04)

Kernel is 4.11.5-1-ARCH

I do know the hardware is ok and works, because if I run an old Suse version it shows me this:

Kernel 3.0.13-0.27-pae

$ lspci
...
00:1f.3 SMBus: Intel Corporation 82801H (ICH8 Family) SMBus Controller (rev 04)


$ i2cdetect -l
i2c-0   smbus           SMBus I801 adapter at 0400              SMBus adapter

$ i2cdetect 0
WARNING! This program can confuse your I2C bus, cause data loss and worse!
I will probe file /dev/i2c-0.
I will probe address range 0x03-0x77.
Continue? [Y/n] Y
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- 08 -- -- -- 0c -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: 20 -- -- -- -- -- -- -- -- -- -- -- -- -- 2e --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- 51 -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- 69 -- -- -- -- -- --
70: -- -- -- -- -- -- -- --

Is there something I missed here?

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#2 2017-06-20 20:49:49

mich41
Member
Registered: 2012-06-22
Posts: 796

Re: i801 i2c-dev not working

Probably acpi_enforce_resources=lax .

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#3 2017-06-20 21:16:22

seth
Member
Registered: 2012-09-03
Posts: 49,986

Re: i801 i2c-dev not working

Tried "modprobe i2c-smbus"?

Edit: probably ninja'd ;-)

Last edited by seth (2017-06-20 21:17:13)

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#4 2017-06-21 07:57:01

zuwarm
Member
Registered: 2017-06-20
Posts: 7

Re: i801 i2c-dev not working

Solved, thx a lot!

'acpi_enforce_resources=lax' did the trick!

$ i2cdetect -l
i2c-3   i2c             i915 gmbus dpc                          I2C adapter
i2c-1   i2c             i915 gmbus vga                          I2C adapter
i2c-6   smbus           SMBus I801 adapter at 0400              SMBus adapter
i2c-4   i2c             i915 gmbus dpb                          I2C adapter
i2c-2   i2c             i915 gmbus panel                        I2C adapter
i2c-0   i2c             i915 gmbus ssc                          I2C adapter
i2c-5   i2c             i915 gmbus dpd                          I2C adapter

It is /dev/i2c-6 now and it does work!

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