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| -rw-r--r-- | Documentation/northbridge/intel/haswell/mrc.bin.md | 77 |
1 files changed, 77 insertions, 0 deletions
diff --git a/Documentation/northbridge/intel/haswell/mrc.bin.md b/Documentation/northbridge/intel/haswell/mrc.bin.md index 36ab4c4385..edfe4b8b84 100644 --- a/Documentation/northbridge/intel/haswell/mrc.bin.md +++ b/Documentation/northbridge/intel/haswell/mrc.bin.md @@ -27,6 +27,83 @@ Now, place `mrc.bin` in the root of the coreboot directory. Alternatively, place `mrc.bin` anywhere you want, and set `MRC_FILE` to its location when building coreboot. +## SPD Addresses + +When porting a board from vendor firmware, the SPD addresses can be obtained +through `i2c-tools`, which can be found in many GNU/Linux distributions. A more +[detailed description](https://hannuhartikainen.fi/blog/hacking-ddr3-spd/) of +the procedure and beyond can be found in +[Hannu Hartikainen's blog](https://hannuhartikainen.fi). + +First load the kernel modules: + +```bash +modprobe i2c-dev +modprobe eeprom +``` + +Find the SMBus and the addresses of the DIMM's EEPROMs (example output): +```bash +$ decode-dimms | grep Decoding +Decoding EEPROM: /sys/bus/i2c/drivers/eeprom/7-0050 +Decoding EEPROM: /sys/bus/i2c/drivers/eeprom/7-0052 +``` + +Alternatively, look at the sys filesystem: +```bash +$ ls -l /sys/bus/i2c/drivers/eeprom/ +total 0 +lrwxrwxrwx 1 root root 0 Apr 4 01:46 6-0050 -> ../../../../devices/pci0000:00/0000:00:02.0/drm/card0/card0-eDP-1/i2c-6/6-0050/ +lrwxrwxrwx 1 root root 0 Apr 4 01:46 7-0050 -> ../../../../devices/pci0000:00/0000:00:1f.3/i2c-7/7-0050/ +lrwxrwxrwx 1 root root 0 Apr 4 01:46 7-0052 -> ../../../../devices/pci0000:00/0000:00:1f.3/i2c-7/7-0052/ +--w------- 1 root root 4096 Apr 4 01:47 bind +lrwxrwxrwx 1 root root 0 Apr 4 01:47 module -> ../../../../module/eeprom/ +--w------- 1 root root 4096 Apr 4 01:46 uevent +--w------- 1 root root 4096 Apr 4 01:47 unbind +``` + +The correct I2C bus is 7 in this case, and the EEPROMs are at `0x50` and `0x52`. +Note that the above values are actually hex values. + +You can check the correctness of the SMBus and the addresses of the EEPROMs via +`i2cdetect`: + +```bash +$ i2cdetect -l +i2c-3 unknown i915 gmbus dpc N/A +i2c-1 unknown i915 gmbus vga N/A +i2c-6 unknown DPDDC-A N/A +i2c-4 unknown i915 gmbus dpb N/A +i2c-2 unknown i915 gmbus panel N/A +i2c-0 unknown i915 gmbus ssc N/A +i2c-7 unknown SMBus I801 adapter at f040 N/A +i2c-5 unknown i915 gmbus dpd N/A +``` + +Probing the SMBus: + +```bash +$ i2cdetect -r 7 +WARNING! This program can confuse your I2C bus, cause data loss and worse! +I will probe file /dev/i2c-7 using receive byte commands. +I will probe address range 0x03-0x77. +Continue? [Y/n] + 0 1 2 3 4 5 6 7 8 9 a b c d e f +00: -- -- -- -- -- -- -- -- -- -- -- -- -- +10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- +20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- +30: 30 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- +40: -- -- -- -- 44 -- -- -- -- -- -- -- -- -- -- -- +50: UU -- UU -- -- -- -- -- -- -- -- -- -- -- -- -- +60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- +70: -- -- -- -- -- -- -- -- +``` + +The SPD addresses need to be left-shifted by 1 for `mrc.bin`, i.e., multiplied +by 2. For example, if the addresses read through `i2c-tools` when booted from +vendor firmware are `0x50` and `0x52`, the correct values would be `0xa0` and +`0xa4`. This is because the I2C addresses are 7 bits long. + ## ECC DRAM When `mrc.bin` has finished executing, ECC is active on the channels |