[PATCH 04/10] arm64: zynqmp: Add 'i2c-mux-idle-disconnect' property

[Michal Simek]

From: Raviteja Narayanam <raviteja.narayanam at 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 at xilinx.com>
Signed-off-by: Michal Simek <michal.simek at 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 at 0 { /* DC_I2C */
 			#address-cells = <1>;
@@ -561,6 +562,7 @@
 		#address-cells = <1>;
 		#size-cells = <0>;
 		reg = <0x75>;
+		i2c-mux-idle-disconnect;
 		i2c at 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 at 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 at 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 at 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 at 0 {
 			#address-cells = <1>;
-- 
2.31.1