linux-kernel - Re: [PATCH] i2c: ismt: Separate I2C block read from SMBus block read

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Message-ID: <61adc1fb-ecb2-7164-ded3-b45cb7d570b5@adiengineering.com>
Date:   Mon, 9 Oct 2017 13:18:20 -0400
From:   Stephen Douthit <stephend@...engineering.com>
To:     Wolfram Sang <wsa@...-dreams.de>,
        Pontus Andersson <epontan@...il.com>
Cc:     Seth Heasley <seth.heasley@...el.com>,
        Neil Horman <nhorman@...driver.com>, linux-i2c@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] i2c: ismt: Separate I2C block read from SMBus block read

 > So, I'll wait for his tests and then send it to Linus ASAP. I think it
 > should be in rc5.

I've been able to confirm the regression my patch introduced, and the
fix from Pontus.

Doing a block read of the SPD EEPROM with my patch everything is shifted
by a byte:

[root@...alhost ~]# i2cdump -y 0 0x50 i
      0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f    0123456789abcdef
00: 13 0b 02 04 21 02 01 03 11 01 08 0a 00 fe 00 69    ????!???????.?.i
10: 78 69 30 69 11 18 81 20 08 3c 3c 00 f0 83 05 80    xi0i??? ?<<.????
20: 00 00 00 00 00 00 00 00 85 00 00 00 00 00 00 00    ........?.......
30: 00 00 00 00 00 00 00 00 00 00 00 0f 01 23 00 00    ...........??#..
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 80 2c 00 00 00 00 00 00 00 a6 dc 39    ....?,.......??9
80: 4b 53 46 35 31 32 37 32 41 5a 2d 31 47 36 45 31    KSF51272AZ-1G6E1
90: 20 45 31 80 2c 00 00 00 00 00 00 00 00 00 00 00     E1?,...........
a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ff    ................
b0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................
c0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................
d0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................
e0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................
f0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 92    ...............?

With the patch from Pontus the I2C block read works as expected:

[root@...alhost ~]# i2cdump -y 0 0x50 i
      0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f    0123456789abcdef
00: 92 13 0b 02 04 21 02 01 03 11 01 08 0a 00 fe 00    ?????!???????.?.
10: 69 78 69 30 69 11 18 81 20 08 3c 3c 00 f0 83 05    ixi0i??? ?<<.???
20: 80 00 00 00 00 00 00 00 00 85 00 00 00 00 00 00    ?........?......
30: 00 00 00 00 00 00 00 00 00 00 00 00 0f 01 23 00    ............??#.
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 80 2c 00 00 00 00 00 00 00 a6 dc    .....?,.......??
80: 39 4b 53 46 35 31 32 37 32 41 5a 2d 31 47 36 45    9KSF51272AZ-1G6E
90: 31 20 45 31 80 2c 00 00 00 00 00 00 00 00 00 00    1 E1?,..........
a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00    ................
b0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................
c0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................
d0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................
e0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................
f0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff    ................

The ipmi_ssif driver still works with this patch, so no issues for
SMBus block reads.

Tested-by: Stephen Douthit <stephend@...engineering.com>