I2C bus got stuck on ls1021aiot based custom board

[dhruvalkumarpat]

Hi All,

I have been experiencing some undefined behavior on i2c bus . I have a 4 devices on ls1021aiot based custom board 

• Temperature ADT7461 (0x4C)     ---- linux driver is attached for this device 
• Board clocking 6V49205B (0x69)  ---- No driver is attached  for this device 
• PMIC MC34VR500V1ES (0x08)   ----- No driver is attached for this device 

• And controller acting as slave at address 0x70 .   ---- linux driver is attached for this device 

When I do i2cdetect on linux I get following 

root@bravo:~# i2cdetect -y 1
0 1 2 3 4 5 6 7 8 9 a b c d e f
00: 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f
10: 10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f
20: 20 21 22 23 24 25 26 27 28 29 2a 2b 2c 2d 2e 2f
30: -- -- -- -- -- -- -- -- 38 39 3a 3b 3c 3d 3e 3f
40: 40 41 42 43 44 45 46 47 48 49 4a 4b UU 4d 4e 4f
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: 60 61 62 63 64 65 66 67 68 69 6a 6b 6c 6d 6e 6f
70: UU 71 72 73 74 75 76 77
root@bravo:~#

And I cannot access any of my devices now ( ADT7461 (0x4C)  and  at address 0x70). I can't figure out why this is happening. When I do reboot it doesn't solve the problem when I power cycle the board all the devices comes back and work fine . I suspect that one of the devices is pulling the SDA line low , not sure though. If any one of you have experience this kind of problem can you please help.  Is there a way to recover it from linux or u-boot. any help or hint  I'll appreciate.

Thanks

Dhruval

[Pavel]

Perhaps that some I2C device on your board requires a few time to start after power up.

Add a delay after power up before I2C device reading.

Have a great day,
Pavel Chubakov

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