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Problem of connecting transceivers with I2C bus #41

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redrattus opened this issue May 16, 2016 · 0 comments
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Problem of connecting transceivers with I2C bus #41

redrattus opened this issue May 16, 2016 · 0 comments

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@redrattus
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redrattus commented May 16, 2016

Hi,

I am now playing with Wedge and making a simple utility that checks status of transceivers through i2c-dev. To this end, I am using the CP2112 device driver which is supported from kernel v3.19. You can check this at http://lxr.free-electrons.com/source/drivers/hid/hid-cp2112.c?v=3.19. Of course, I am using kernel v3.19.

Then, using I2C-tools I can find devices that connected with I2C bus (i.e., i2c-1). The message is as below:
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- 2a -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- 51 -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- 74 -- 76 --

0x51 for FRU_EEPROM
0x74 for I2C Mux1
0x76 for I2C Mux2

As you might know, to establish the channel connecting to the transceiver#1, you first write a proper value (i.e., 0x02 for the mux1, 0x00 for the mux2) to the control register in I2C Muxes with the i2c_smbus_write_byte() defined in SMBus spec. However, this might not work for me. The transceiver is not presented at I2C bus (i.e., 0x50).

Anyone who tries this?

arajeev-ARISTA pushed a commit to arajeev-ARISTA/fboss that referenced this issue Sep 26, 2023
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