tree 46976ded32d7db332aa56d8c8c9e7838a5161aa0
parent 342c3cdfe8802bba8a19efbc927d2cc48e9e9e16
author Raviteja Narayanam <raviteja.narayanam@xilinx.com> 1617282850 -0600
committer Michal Simek <michal.simek@xilinx.com> 1621410290 +0200

arm64: zynqmp: Add 'i2c-mux-idle-disconnect' property

I2C muxes that have the slave devices with same address are
falling into the below problem.

VCK190 system controller (SC) - zynqmp-e-a2197-00-revA.dts
I2C1 (0xff030000) -> Mux1 (@0x74) -> Channel 3 -> 0x50
I2C1 (0xff030000) -> Mux2 (@0x75) -> Channel 0 -> 0x50

1. SC accesses I2C1 - Mux1 (0x74) - Channel 3 and then
2. SC accesses I2C1 - Mux2 (0x75) - Channel 0.

Now it results in 2 slave devices with same address (0x50)
on the I2C bus, making the communication un-reliable.

When ' i2c-mux-idle-disconnect' is in DT, after '1', the Mux
channel output is disconnected, making none of the channels
available to the I2C1. So, there is no question of having the
same addressed slave (0x50) present on the bus when we are doing '2'.

Same pattern is seen in below two boards also.

ZCU208 - zynqmp-zcu208-revA.dts
ZCU216 - zynqmp-zcu216-revA.dts

Signed-off-by: Raviteja Narayanam <raviteja.narayanam@xilinx.com>