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

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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>
This commit is contained in:
Raviteja Narayanam 2021-04-01 07:14:10 -06:00 committed by Michal Simek
parent 000b862325
commit 486f25c727
3 changed files with 6 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/arm/dts/zynqmp-e-a2197-00-revA.dts
View File

@ -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>;

2
arch/arm/dts/zynqmp-zcu208-revA.dts
View File

@ -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>;

2
arch/arm/dts/zynqmp-zcu216-revA.dts
View File

@ -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>;