Documentation/northbridge/intel/haswell/mrc.bin.md: add SPD addresses
Change-Id: I8bf81637f582373d9bba1d47fe5205d459151f3e Signed-off-by: Daniel Maslowski <dan@orangecms.org> Reviewed-on: https://review.coreboot.org/c/coreboot/+/32473 Tested-by: build bot (Jenkins) <no-reply@coreboot.org> Reviewed-by: Patrick Rudolph <siro@das-labor.org>
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@ -27,6 +27,83 @@ Now, place `mrc.bin` in the root of the coreboot directory.
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Alternatively, place `mrc.bin` anywhere you want, and set `MRC_FILE` to
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its location when building coreboot.
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## SPD Addresses
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When porting a board from vendor firmware, the SPD addresses can be obtained
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through `i2c-tools`, which can be found in many GNU/Linux distributions. A more
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[detailed description](https://hannuhartikainen.fi/blog/hacking-ddr3-spd/) of
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the procedure and beyond can be found in
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[Hannu Hartikainen's blog](https://hannuhartikainen.fi).
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First load the kernel modules:
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```bash
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modprobe i2c-dev
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modprobe eeprom
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```
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Find the SMBus and the addresses of the DIMM's EEPROMs (example output):
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```bash
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$ decode-dimms | grep Decoding
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Decoding EEPROM: /sys/bus/i2c/drivers/eeprom/7-0050
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Decoding EEPROM: /sys/bus/i2c/drivers/eeprom/7-0052
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```
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Alternatively, look at the sys filesystem:
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```bash
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$ ls -l /sys/bus/i2c/drivers/eeprom/
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total 0
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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/
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lrwxrwxrwx 1 root root 0 Apr 4 01:46 7-0050 -> ../../../../devices/pci0000:00/0000:00:1f.3/i2c-7/7-0050/
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lrwxrwxrwx 1 root root 0 Apr 4 01:46 7-0052 -> ../../../../devices/pci0000:00/0000:00:1f.3/i2c-7/7-0052/
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--w------- 1 root root 4096 Apr 4 01:47 bind
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lrwxrwxrwx 1 root root 0 Apr 4 01:47 module -> ../../../../module/eeprom/
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--w------- 1 root root 4096 Apr 4 01:46 uevent
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--w------- 1 root root 4096 Apr 4 01:47 unbind
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```
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The correct I2C bus is 7 in this case, and the EEPROMs are at `0x50` and `0x52`.
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Note that the above values are actually hex values.
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You can check the correctness of the SMBus and the addresses of the EEPROMs via
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`i2cdetect`:
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```bash
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$ i2cdetect -l
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i2c-3 unknown i915 gmbus dpc N/A
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i2c-1 unknown i915 gmbus vga N/A
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i2c-6 unknown DPDDC-A N/A
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i2c-4 unknown i915 gmbus dpb N/A
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i2c-2 unknown i915 gmbus panel N/A
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i2c-0 unknown i915 gmbus ssc N/A
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i2c-7 unknown SMBus I801 adapter at f040 N/A
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i2c-5 unknown i915 gmbus dpd N/A
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```
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Probing the SMBus:
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```bash
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$ i2cdetect -r 7
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WARNING! This program can confuse your I2C bus, cause data loss and worse!
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I will probe file /dev/i2c-7 using receive byte commands.
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I will probe address range 0x03-0x77.
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Continue? [Y/n]
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0 1 2 3 4 5 6 7 8 9 a b c d e f
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00: -- -- -- -- -- -- -- -- -- -- -- -- --
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10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
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20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
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30: 30 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
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40: -- -- -- -- 44 -- -- -- -- -- -- -- -- -- -- --
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50: UU -- UU -- -- -- -- -- -- -- -- -- -- -- -- --
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60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
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70: -- -- -- -- -- -- -- --
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```
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The SPD addresses need to be left-shifted by 1 for `mrc.bin`, i.e., multiplied
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by 2. For example, if the addresses read through `i2c-tools` when booted from
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vendor firmware are `0x50` and `0x52`, the correct values would be `0xa0` and
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`0xa4`. This is because the I2C addresses are 7 bits long.
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## ECC DRAM
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When `mrc.bin` has finished executing, ECC is active on the channels
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