From: Raviteja Narayanam raviteja.narayanam@xilinx.com
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 Signed-off-by: Michal Simek michal.simek@xilinx.com ---
arch/arm/dts/zynqmp-e-a2197-00-revA.dts | 2 ++ arch/arm/dts/zynqmp-zcu208-revA.dts | 2 ++ arch/arm/dts/zynqmp-zcu216-revA.dts | 2 ++ 3 files changed, 6 insertions(+)
diff --git a/arch/arm/dts/zynqmp-e-a2197-00-revA.dts b/arch/arm/dts/zynqmp-e-a2197-00-revA.dts index ffa3dbb5f71f..8ec2e866535b 100644 --- a/arch/arm/dts/zynqmp-e-a2197-00-revA.dts +++ b/arch/arm/dts/zynqmp-e-a2197-00-revA.dts @@ -457,6 +457,7 @@ #address-cells = <1>; #size-cells = <0>; reg = <0x74>; + i2c-mux-idle-disconnect; /* reset-gpios = <&gpio SYSCTLR_IIC_MUX1_RESET_B GPIO_ACTIVE_HIGH>; */ dc_i2c: i2c@0 { /* DC_I2C */ #address-cells = <1>; @@ -561,6 +562,7 @@ #address-cells = <1>; #size-cells = <0>; reg = <0x75>; + i2c-mux-idle-disconnect; i2c@0 { /* SFP0_IIC */ #address-cells = <1>; #size-cells = <0>; diff --git a/arch/arm/dts/zynqmp-zcu208-revA.dts b/arch/arm/dts/zynqmp-zcu208-revA.dts index 0e114cdacb1a..c24301090dde 100644 --- a/arch/arm/dts/zynqmp-zcu208-revA.dts +++ b/arch/arm/dts/zynqmp-zcu208-revA.dts @@ -388,6 +388,7 @@ #address-cells = <1>; #size-cells = <0>; reg = <0x74>; + i2c-mux-idle-disconnect; /* FIXME reset-gpios = <&tca6416_u15 SYSCTLR_IIC_MUX0_RESET_B GPIO_ACTIVE_HIGH>; */ i2c_eeprom: i2c@0 { #address-cells = <1>; @@ -504,6 +505,7 @@ #address-cells = <1>; #size-cells = <0>; reg = <0x75>; + i2c-mux-idle-disconnect; /* FIXME reset-gpios = <&tca6416_u15 SYSCTLR_IIC_MUX0_RESET_B GPIO_ACTIVE_HIGH>; */ i2c@0 { #address-cells = <1>; diff --git a/arch/arm/dts/zynqmp-zcu216-revA.dts b/arch/arm/dts/zynqmp-zcu216-revA.dts index 2302b07c4825..675baf4bed61 100644 --- a/arch/arm/dts/zynqmp-zcu216-revA.dts +++ b/arch/arm/dts/zynqmp-zcu216-revA.dts @@ -399,6 +399,7 @@ #address-cells = <1>; #size-cells = <0>; reg = <0x74>; + i2c-mux-idle-disconnect; /* FIXME reset-gpios = <&tca6416_u15 SYSCTLR_IIC_MUX0_RESET_B GPIO_ACTIVE_HIGH>; */ i2c_eeprom: i2c@0 { #address-cells = <1>; @@ -515,6 +516,7 @@ #address-cells = <1>; #size-cells = <0>; reg = <0x75>; + i2c-mux-idle-disconnect; /* FIXME reset-gpios = <&tca6416_u15 SYSCTLR_IIC_MUX0_RESET_B GPIO_ACTIVE_HIGH>; */ i2c@0 { #address-cells = <1>;