[lm-sensors] not fan detected chromebook c720

[lm-sensors] not fan detected chromebook c720

[Pietro Sammarco]

Hello people,

I have recently bought a brand new Acer chromebook c720 which I am using 
with ArchLinux. Ever since I wiped out ChromeOS to install ArchLinux I 
realized a smell of electronic burning coming from it. Digging around I 
have realized lm-sensors does not detect the fan.

The chipset is a Lynx Point (PCH), therefore as according the wiki it 
should work with the i2c-i801.

I am going to attach a bit of informations below.

Linux chromebookC720 3.16.0-1-mainline-chromebook #1 SMP PREEMPT Mon Jul 
14 22:04:51 NZST 2014 x86_64 GNU/Linux

[latrina@chromebookC720 ~]$ sudo i2cdetect -l
i2c-0    i2c           i2c-designware-pci                  I2C adapter
i2c-1    i2c           i2c-designware-pci                  I2C adapter
i2c-2    smbus         SMBus I801 adapter at 0400          SMBus adapter
i2c-3    i2c           i915 gmbus ssc                      I2C adapter
i2c-4    i2c           i915 gmbus vga                      I2C adapter
i2c-5    i2c           i915 gmbus panel                    I2C adapter
i2c-6    i2c           i915 gmbus dpc                      I2C adapter
i2c-7    i2c           i915 gmbus dpb                      I2C adapter
i2c-8    i2c           i915 gmbus dpd                      I2C adapter
i2c-9    i2c           DPDDC-A                             I2C adapter

[latrina@chromebookC720 ~]$ sudo lspci -nn |grep SMBus
00:1f.3 SMBus [0c05]: Intel Corporation 8 Series SMBus Controller 
[8086:9c22] (rev 04)

[latrina@chromebookC720 ~]$ sudo lsmod |grep i2c
i2c_dev                 6953  0
i2c_i801               11301  0
i2c_designware_platform     3325  0
i2c_designware_pci      3931  0
i2c_designware_core     7013  2 i2c_designware_pci,i2c_designware_platform
i2c_algo_bit            5480  1 i915
i2c_core               41648  12 
drm,i2c_designware_pci,i915,i2c_i801,i2c_dev,cyapa,i2c_designware_platform,drm_kms_helper,i2c_algo_bit,v4l2_common,chromeos_laptop,videodev

[latrina@chromebookC720 ~]$ sensors -u
coretemp-isa-0000
Adapter: ISA adapter
Core 0:
   temp1_input: 46.000
   temp1_max: 100.000
   temp1_crit: 100.000
   temp1_crit_alarm: 0.000
Core 1:
   temp2_input: 46.000
   temp2_max: 100.000
   temp2_crit: 100.000
   temp2_crit_alarm: 0.000
Core 2:
   temp3_input: 46.000
   temp3_max: 100.000
   temp3_crit: 100.000
   temp3_crit_alarm: 0.000


[latrina@chromebookC720 ~]$ sudo sensors-detect
# sensors-detect revision 6209 (2014-01-14 22:51:58 +0100)
# System: Acer Peppy [1.0]

This program will help you determine which kernel modules you need
to load to use lm_sensors most effectively. It is generally safe
and recommended to accept the default answers to all questions,
unless you know what you're doing.

Some south bridges, CPUs or memory controllers contain embedded sensors.
Do you want to scan for them? This is totally safe. (YES/no):
Module cpuid loaded successfully.
Silicon Integrated Systems SIS5595...                       No
VIA VT82C686 Integrated Sensors...                          No
VIA VT8231 Integrated Sensors...                            No
AMD K8 thermal sensors...                                   No
AMD Family 10h thermal sensors...                           No
AMD Family 11h thermal sensors...                           No
AMD Family 12h and 14h thermal sensors...                   No
AMD Family 15h thermal sensors...                           No
AMD Family 15h power sensors...                             No
AMD Family 16h power sensors...                             No
Intel digital thermal sensor...                             Success!
     (driver `coretemp')
Intel AMB FB-DIMM thermal sensor...                         No
VIA C7 thermal sensor...                                    No
VIA Nano thermal sensor...                                  No

Some Super I/O chips contain embedded sensors. We have to write to
standard I/O ports to probe them. This is usually safe.
Do you want to scan for Super I/O sensors? (YES/no):
Probing for Super-I/O at 0x2e/0x2f
Trying family `National Semiconductor/ITE'...               No
Trying family `SMSC'...                                     No
Trying family `VIA/Winbond/Nuvoton/Fintek'...               No
Trying family `ITE'...                                      No
Probing for Super-I/O at 0x4e/0x4f
Trying family `National Semiconductor/ITE'...               No
Trying family `SMSC'...                                     No
Trying family `VIA/Winbond/Nuvoton/Fintek'...               No
Trying family `ITE'...                                      No

Some systems (mainly servers) implement IPMI, a set of common interfaces
through which system health data may be retrieved, amongst other things.
We first try to get the information from SMBIOS. If we don't find it
there, we have to read from arbitrary I/O ports to probe for such
interfaces. This is normally safe. Do you want to scan for IPMI
interfaces? (YES/no):
Probing for `IPMI BMC KCS' at 0xca0...                      No
Probing for `IPMI BMC SMIC' at 0xca8...                     No

Some hardware monitoring chips are accessible through the ISA I/O ports.
We have to write to arbitrary I/O ports to probe them. This is usually
safe though. Yes, you do have ISA I/O ports even if you do not have any
ISA slots! Do you want to scan the ISA I/O ports? (YES/no):
Probing for `National Semiconductor LM78' at 0x290...       No
Probing for `National Semiconductor LM79' at 0x290...       No
Probing for `Winbond W83781D' at 0x290...                   No
Probing for `Winbond W83782D' at 0x290...                   No

Lastly, we can probe the I2C/SMBus adapters for connected hardware
monitoring devices. This is the most risky part, and while it works
reasonably well on most systems, it has been reported to cause trouble
on some systems.
Do you want to probe the I2C/SMBus adapters now? (YES/no):
Found unknown SMBus adapter 8086:9c22 at 0000:00:1f.3.
Sorry, no supported PCI bus adapters found.

Next adapter: i2c-designware-pci (i2c-0)
Do you want to scan it? (YES/no/selectively):
Adapter doesn't support all probing functions.
Some addresses won't be probed.

Next adapter: i2c-designware-pci (i2c-1)
Do you want to scan it? (YES/no/selectively):
Adapter doesn't support all probing functions.
Some addresses won't be probed.

Next adapter: SMBus I801 adapter at 0400 (i2c-2)
Do you want to scan it? (YES/no/selectively):

Next adapter: i915 gmbus ssc (i2c-3)
Do you want to scan it? (yes/NO/selectively):

Next adapter: i915 gmbus vga (i2c-4)
Do you want to scan it? (yes/NO/selectively):

Next adapter: i915 gmbus panel (i2c-5)
Do you want to scan it? (yes/NO/selectively):

Next adapter: i915 gmbus dpc (i2c-6)
Do you want to scan it? (yes/NO/selectively):

Next adapter: i915 gmbus dpb (i2c-7)
Do you want to scan it? (yes/NO/selectively):

Next adapter: i915 gmbus dpd (i2c-8)
Do you want to scan it? (yes/NO/selectively):

Next adapter: DPDDC-A (i2c-9)
Do you want to scan it? (yes/NO/selectively):


Now follows a summary of the probes I have just done.
Just press ENTER to continue:

Driver `coretemp':
   * Chip `Intel digital thermal sensor' (confidence: 9)

Do you want to generate /etc/conf.d/lm_sensors? (YES/no):
Unloading cpuid... OK

-------------------------------------------------------------------------------------------

Hopefully someone will able to tell me what I am doing wrong.

Thanks,
Pietro


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Re: [lm-sensors] not fan detected chromebook c720

[Guenter Roeck]

On 07/24/2014 03:53 PM, Pietro Sammarco wrote:
> Hello people,
>
> I have recently bought a brand new Acer chromebook c720 which I am using with ArchLinux. Ever since I wiped out ChromeOS to install ArchLinux I realized a smell of electronic burning coming from it. Digging around I have realized lm-sensors does not detect the fan.
>
> The chipset is a Lynx Point (PCH), therefore as according the wiki it should work with the i2c-i801.
>
> I am going to attach a bit of informations below.
>
> Linux chromebookC720 3.16.0-1-mainline-chromebook #1 SMP PREEMPT Mon Jul 14 22:04:51 NZST 2014 x86_64 GNU/Linux
>
> [latrina@chromebookC720 ~]$ sudo i2cdetect -l
> i2c-0    i2c           i2c-designware-pci                  I2C adapter
> i2c-1    i2c           i2c-designware-pci                  I2C adapter
> i2c-2    smbus         SMBus I801 adapter at 0400          SMBus adapter


Well, it does, as you can see here.

Problem is that the fan controller is not detected, which suggests
that ChromeOS includes a fan controller driver for your system
which is not included in the upstream kernel and thus not in ArchLinux.
Detecting and instantiating the SMBus controller won't help you with
detecting the fan controller, much less with installing a driver for it.

You could try to get the ChromeOS kernel source, figure out how they
control the fans, and port the necessary code to ArchLinux. I don't know
if there is anything else you could do.

Guenter


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Re: [lm-sensors] not fan detected chromebook c720

[Jean Delvare]

On Thu, 24 Jul 2014 17:53:50 -0500, Pietro Sammarco wrote:
> Hello people,
> 
> I have recently bought a brand new Acer chromebook c720 which I am using 
> with ArchLinux. Ever since I wiped out ChromeOS to install ArchLinux I 
> realized a smell of electronic burning coming from it. Digging around I 
> have realized lm-sensors does not detect the fan.

What did ChromeOS report with regards to hardware monitoring?

If this machine has anything which looks like a BIOS, what does it
report with regards to hardware monitoring?

Most laptops don't have traditional hardware monitoring chips,
everything is handled by ACPI magic and/or behind complex environment
controller chips.

> The chipset is a Lynx Point (PCH), therefore as according the wiki it 
> should work with the i2c-i801.
> 
> I am going to attach a bit of informations below.
> 
> Linux chromebookC720 3.16.0-1-mainline-chromebook #1 SMP PREEMPT Mon Jul 
> 14 22:04:51 NZST 2014 x86_64 GNU/Linux
> 
> [latrina@chromebookC720 ~]$ sudo i2cdetect -l
> i2c-0    i2c           i2c-designware-pci                  I2C adapter
> i2c-1    i2c           i2c-designware-pci                  I2C adapter
> i2c-2    smbus         SMBus I801 adapter at 0400          SMBus adapter
> i2c-3    i2c           i915 gmbus ssc                      I2C adapter
> i2c-4    i2c           i915 gmbus vga                      I2C adapter
> i2c-5    i2c           i915 gmbus panel                    I2C adapter
> i2c-6    i2c           i915 gmbus dpc                      I2C adapter
> i2c-7    i2c           i915 gmbus dpb                      I2C adapter
> i2c-8    i2c           i915 gmbus dpd                      I2C adapter
> i2c-9    i2c           DPDDC-A                             I2C adapter

I'm surprised by the designware stuff, instead I would expected
cros-ec-i2c-tunnel. Can you check if the i2c-cros-ec-tunnel driver is
loaded (as well as the cros_ec driver itself)?

> Hopefully someone will able to tell me what I am doing wrong.

Nothing, it's just a non-trivial case.

-- 
Jean Delvare
SUSE L3 Support

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Re: [lm-sensors] not fan detected chromebook c720

[Jean Delvare]

Hi Pietro,

Please keep the list Cc'd.

On Fri, 25 Jul 2014 11:46:39 -0500, Pietro Sammarco wrote:
> >I'm surprised by the designware stuff, instead I would expected
> >cros-ec-i2c-tunnel. Can you check if the i2c-cros-ec-tunnel driver is
> >loaded (as well as the cros_ec driver itself)?
> 
> In regard of this, i2c-cros-ec-tunnel cannot be found, while cros_ec 
> wasn't loaded. What are exactly those two kernel modules supposed to do?

The cros_ec driver is handing the "embedded controller" of some
ChromeOS laptops. See this as a gate to access other components /
features of the mainboard. i2c-cros-ec-tunnel is on of these
components, which gives access to a secondary I2C bus distinct from the
Intel PCH SMBus. My idea was that maybe there was some hardware
monitoring chip on that secondary I2C bus.

You should try to find out if the cros_ec driver is needed on your
laptop. Maybe it is, maybe not. BTW the cros_ec module itself is only a
helper module, the actual driver is cros_ec_i2c or cros_ec_spi
depending on the laptop model.

I don't know much about ChromeOS hardware myself, so I can only give
you vague hints, take these with a grain of salt, I may be off-track.

> I am going to go a bit offtopic now. The real issue whit my c720 in 
> particular is that the part of the motherboard at the opposite side of 
> the fan gets quite hotter after an hour of use (look the part numbered 5 
> in the c720 picture, that's exactly where the intense smell comes from 
> hthttp://www.chromium.org/_/rsrc/1381990807648/chromium-os/developer-information-for-chrome-os-devices/acer-c720-chromebook/c720-chromebook-annotated-innards.png 
> ), and its when the burning of electronic smells starts to come out. 
> Therefore I would assume the firmware that handles the fan speed simply 
> doesn't do enough for my chromebook, and since lm-sensors doesn't yet 
> work with it, I need to know a way to manually increase the fan speed 
> RPM min, max and per temperature so that there will be enough 
> ventilation all across the motherboard for the laptop to cool off properly.
> 
> At the same time I am going to do some further investigations in regard 
> of how ChromeOS exactly handles thermal and fan control.

You should be very careful, I doubt the hardware will last long in
these conditions. Using an external cooling system until you get things
sorted out may help.

Note that getting lm-sensors to work would probably not solve your
problem. In the best case, it will tell you how fast the fan is
spinning. It is unlikely that it will give your control of the fan
speed, that's almost always handled by the firmware on laptops.

Also note that the problem may not be the cooling per se. I have a
laptop with a discrete graphics chip which heats more than the CPU when
the graphics driver doesn't perform proper power management. That
machine worked fine with the binary graphics driver from the vendor.
Once I switched to the open source driver (I had no choice as the
binary driver was no longer maintained) the machine started overheating.

The thing marked with "1" in the picture you sent, seems to generate
some heat, and is not far away from the area you say is getting hot.

It could also be an issue with the CPU. You should check that things
like CPU idle and CPUFreq are working properly. If the CPU doesn't get
proper power management, the fan may be simply unable to cope with the
generated heat. So you should perform some analysis with tools such as
powertop.

-- 
Jean Delvare
SUSE L3 Support

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