Re: [ee1004] Failed to select page 0 - G.Skill Trident Z5 NEO DDR5, ASUS X670E board - 6.2.11-arch1-1

[Jean Delvare <jdelvare@suse.de>]

Hi Jean-François,

On Fri, 21 Apr 2023 06:35:34 +0200, Wolfram Sang wrote:
> On Thu, Apr 20, 2023 at 03:51:38PM -0700, Jean-François Roy wrote:
> > On a ASUS X670E (AMD AM5 platform) board, I am unable to read the
> > eeprom for my memory (through decode-dimms). The SMBus is driven by
> > piix4_smbus.
> > 
> > i2cdetect -l lists the following:
> > 
> > i2c-0   i2c             Synopsys DesignWare I2C adapter         I2C adapter
> > i2c-1   i2c             NVIDIA i2c adapter 2 at 1:00.0          I2C adapter
> > i2c-2   i2c             NVIDIA i2c adapter 3 at 1:00.0          I2C adapter
> > i2c-3   i2c             NVIDIA i2c adapter 4 at 1:00.0          I2C adapter
> > i2c-4   i2c             NVIDIA i2c adapter 5 at 1:00.0          I2C adapter
> > i2c-5   i2c             NVIDIA i2c adapter 6 at 1:00.0          I2C adapter
> > i2c-6   smbus           SMBus PIIX4 adapter port 0 at 0b00      SMBus adapter
> > i2c-7   smbus           SMBus PIIX4 adapter port 2 at 0b00      SMBus adapter
> > i2c-8   smbus           SMBus PIIX4 adapter port 1 at 0b20      SMBus adapter
> > 
> > Looking at i2c-6:
> > 
> > i2cdetect -y 6 0x50 0x70
> >      0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
> > 00:
> > 10:
> > 20:
> > 30:
> > 40:
> > 50: -- 51 -- 53 -- -- -- -- -- -- -- -- -- -- -- --
> > 60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
> > 70: --
> > 
> > I think those are the memory eeproms. If I bind them to ee1004 as so:

They indeed most likely are.

> > echo ee1004 0x51 >/sys/bus/i2c/devices/i2c-6/new_device
> > echo ee1004 0x53 >/sys/bus/i2c/devices/i2c-6/new_device
> > 
> > The kernel prints:
> > 
> > [ 1642.373579] ee1004 6-0051: 512 byte EE1004-compliant SPD EEPROM, read-only
> > [ 1642.373588] i2c i2c-6: new_device: Instantiated device ee1004 at 0x51
> > [ 1645.328289] ee1004 6-0053: 512 byte EE1004-compliant SPD EEPROM, read-only
> > [ 1645.328299] i2c i2c-6: new_device: Instantiated device ee1004 at 0x53
> > 
> > But then when I use decode-dimms, the kernel is unable to select page 0:
> > 
> > [ 1697.112564] ee1004 6-0051: Failed to select page 0 (-6)
> > [ 1702.581605] ee1004 6-0051: Failed to select page 0 (-6)

According to the technical documentation, the ASUS X670E uses DDR5
SDRAM. The EE1004 EEPROMs are the standard used on DDR4 SDRAM memory
modules. I did not look into DDR5 SPD support yet, but your testing
above suggests that DDR5 modules are using an EEPROM standard which is
not compatible with EE1004.

I took a quick look on jedec.org in search for information and found
JESD400-5A which covers SPD contents for DDR5 and it enumerates 1024
bytes. This is twice as much as what EE1004 EEPROMs can hold, so DDR5
modules are definitely not using EE1004 EEPROMs. So far I couldn't find
the "equivalent" of EE1004 for DDR5 modules so far.

Anyway, note that there's currently no support for DDR5 in
decode-dimms, so even after figuring out how to deal with DDR5 module
SPD EEPROMs on the kernel side, we will also have to add full decoding
support for DDR5 SPD fields to that script. The document weights 117
pages so it's a pretty serious amount of work.

-- 
Jean Delvare
SUSE L3 Support