| 1 | What is it? |
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| 2 | ----------- |
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| 3 | |
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| 4 | NOTE: |
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| 5 | This module is for 2.4 kernels only. For 2.6 kernels, |
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| 6 | activation is handled by the code in drivers/pci/quirks.c |
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| 7 | in the kernel source. If you have the latest 2.6 kernel and |
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| 8 | the quirks code does not activate your SMBus, try adding support |
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| 9 | in quirks.c, recompile and test your new kernel, and then |
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| 10 | submit a patch to us. Contact us if you need assistance. |
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| 11 | |
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| 12 | This is just a quick and dirty hack to get the hardware monitoring working |
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| 13 | on the ASUS P4B board under Linux. |
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| 14 | It works by turning on the SMBus PCI device. |
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| 15 | It is implemented as a module, p4b_smbus.o. |
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| 16 | It only works with the ICH2 (82801BA) and ICH4 (82801DB). |
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| 17 | |
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| 18 | ASUS switches off the SMBus PCI Device |
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| 19 | in the i801 ICH2/4 chip. I spoke two times |
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| 20 | with the German support and learned that: "We do not want the users to be |
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| 21 | irritated by just another PCI Device in the Win98 device manager." |
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| 22 | Really funny :-). |
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| 23 | |
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| 24 | NOTE: We have a report that as of kernel 2.4.23, the kernel activates |
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| 25 | the SMBus PCI device, so that this module is not required. |
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| 26 | |
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| 27 | |
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| 28 | What does the module do? |
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| 29 | ------------------------ |
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| 30 | (Note: the following instructions assume the ICH2. For the ICH4, |
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| 31 | the PCI IDs are 24C0 and 24C3) |
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| 32 | |
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| 33 | It turnes off (!) the bits number 8 and 3 in the LPC register of the ICH2. |
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| 34 | This you can also try as root with setpci and pcitweak. |
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| 35 | First do a: |
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| 36 | |
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| 37 | setpci -d 8086:2440 f2.w |
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| 38 | |
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| 39 | You will get an hex number VAL - in my case 148 (Hex)-, where you have to |
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| 40 | erase the two bits - in my case you get 40 (Hex). |
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| 41 | Then do a: |
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| 42 | |
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| 43 | setpci -d 8086:2440 f2.w=VAL |
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| 44 | |
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| 45 | Running "lspci -n" you will not see any new device, but with "pcitweak -l" you |
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| 46 | should get a line similar to this in the output: |
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| 47 | |
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| 48 | PCI: 00:1f:3: chip 8086,2443 card 1043,8028 rev 12 class 0c,05,00 hdr 00 |
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| 49 | |
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| 50 | The important thing is the "8086,2443" here. |
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| 51 | The device is activated, but not included in /proc/pci and |
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| 52 | /proc/bus/pci/devices. This is the reason for running the module. |
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| 53 | |
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| 54 | What are the system requirements? |
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| 55 | --------------------------------- |
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| 56 | |
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| 57 | - Obviously a board with Intel i801BA/DB ICH2/4 with broken bios. |
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| 58 | - A linux working with a 2.4 kernel AND hotplug support in it! |
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| 59 | - A installed kernel tree and gcc. |
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| 60 | - i2c and sensor modules installed. |
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| 61 | |
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| 62 | How to install? |
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| 63 | --------------- |
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| 64 | |
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| 65 | Simply do a: |
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| 66 | |
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| 67 | make -f Makefile.p4b |
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| 68 | insmod p4b_smbus.o |
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| 69 | modprobe i2c-core |
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| 70 | modprobe i2c-i801 |
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| 71 | modprobe i2c-dev |
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| 72 | modprobe i2c-proc |
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| 73 | |
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| 74 | Then run your sensor: |
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| 75 | |
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| 76 | modprobe w83781d |
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| 77 | |
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| 78 | What should i never do? |
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| 79 | ----------------------- |
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| 80 | |
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| 81 | Do not try to do a "rmmod p4b_smbus" before a "rmmod i2c-i801". |
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| 82 | The other way around should be okay. Otherwise you remove the PCI device |
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| 83 | without notifying the i2c driver. |
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| 84 | |
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| 85 | |
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| 86 | ------------------------------- |
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| 87 | Ilja Rauhut <IljaRauhut@web.de> |
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| 88 | |
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