linux-kernel - Re: [PATCH v4 5/6] i2c: smbus: Support DDR5 SPD EEPROMs

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Message-ID: <f76a4d07-887b-4efb-b20e-52979db31216@roeck-us.net>
Date: Tue, 18 Jun 2024 07:23:31 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Paul Menzel <pmenzel@...gen.mpg.de>
Cc: linux-hwmon@...r.kernel.org, linux-i2c@...r.kernel.org,
 linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
 Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Wolfram Sang <wsa+renesas@...g-engineering.com>,
 René Rebe <rene@...ctcode.de>,
 Thomas Weißschuh <linux@...ssschuh.net>,
 Armin Wolf <W_Armin@....de>, Stephen Horvath <s.horvath@...look.com.au>
Subject: Re: [PATCH v4 5/6] i2c: smbus: Support DDR5 SPD EEPROMs

On 6/18/24 06:51, Paul Menzel wrote:
> Dear Guenter,
> 
> 
> Am 18.06.24 um 15:32 schrieb Guenter Roeck:
> 
>> On 6/18/24 03:25, Paul Menzel wrote:
>> [ ... ]
>>>
>>>      $ ls -l /sys/bus/i2c/drivers/spd5118/0-0050/eeprom
>>>      -r--r--r-- 1 root root 1024 Jun 18 12:17 /sys/bus/i2c/drivers/spd5118/0-0050/eeprom
>>>      $ cp /sys/bus/i2c/drivers/spd5118/0-0050/eeprom /tmp
>>>      cp: error reading '/sys/bus/i2c/drivers/spd5118/0-0050/eeprom': No such device or address
>>
>> That suggests that the i801 driver got an error when trying some chip operation.
>> Unfortunately I have no idea what that error or the failed operation might be.
>>
>>>      $ od -t x1 /sys/bus/i2c/drivers/spd5118/0-0050/eeprom
>>>      od: /sys/bus/i2c/drivers/spd5118/0-0050/eeprom: read error: No such device or address
>>>      0000000
>>>
>>>> sudo i2cdump -y -f 0 0x50
>>>
>>>      $ sudo LD_LIBRARY_PATH=~/src/i2c-tools/lib tools/i2cdump -y -f 0 0x50
>>>      No size specified (using byte-data access)
>>>      Error: Could not open file `/dev/i2c-0' or `/dev/i2c/0': No such file or directory
>>>
>> This should work after you load the "i2c-dev" module.
> 
> Silly me. Thank you.
> 
>> If you get it to work, please provide the output. Maybe it helps tracking down the problem.
> 
> ```
> $ sudo LD_LIBRARY_PATH=~/src/i2c-tools/lib tools/i2cdump -y -f 0 0x50
> No size specified (using byte-data access)
>       0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f    0123456789abcdef
> 00: 51 18 0a 86 32 03 32 00 00 00 00 00 ff 01 00 00    Q???2?2......?..
> 10: 00 00 00 00 00 00 00 00 00 00 00 00 70 03 00 00    ............p?..
> 20: 50 05 00 00 00 00 00 00 00 00 00 00 00 00 00 00    P?..............
> 30: 00 58 01 00 00 00 00 00 00 00 00 00 00 00 00 00    .X?.............
> 40: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
> 50: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
> 60: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
> 70: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
> 80: 30 10 12 02 04 00 20 62 00 00 00 00 90 02 00 00    0????. b....??..
> 90: 00 00 00 00 a0 01 f2 03 7a 0d 00 00 00 00 80 3e    ....????z?....?>
> a0: 80 3e 80 3e 00 7d 80 bb 30 75 27 01 a0 00 82 00    ?>?>.}??0u'??.?.
> b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
> c0: 00 00 00 00 00 00 88 13 08 88 13 08 20 4e 20 10    ......?????? N ?
> d0: 27 10 15 34 20 10 27 10 c4 09 04 4c 1d 0c 00 00    '??4 ?'????L??..
> e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
> f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
> ```
> 
> So (00,b) = 0x00 opposed to 0x07 in your example output.
> 

Yes, that assumed that reading the nvram/eeprom succeeded, which it didn't.
The value might also be 7 directly after booting and before loading
the spd5118 driver.

Anyway, it almost looks like setting the page doesn't work, or maybe write
operations in general.

Can you try the following ?

dd if=/sys/bus/i2c/drivers/spd5118/0-0050/eeprom of=/tmp/eeprom count=64 bs=1

and

dd if=/sys/bus/i2c/drivers/spd5118/0-0050/eeprom of=/tmp/eeprom count=1 bs=64

That should only try to read from page 0.

Also, please try to set a temperature limit, either temp1_max
or temp1_crit. Setting temp1_max to, say, 56000, or temp1_crit
to 84000 should do.

Thanks,
Guenter