TMDX654GPEVM: I2C access to PLL on SERDES board

Just a clarification:

0x76 I2C address is specified in the document named "PROC062E3(003)_SCH.pdf" at page 8:

Please check "Clock Generator" on Serdes Card

Hi Genesio,

You commented that you shorted R120 and R121.  These are not the correct resistors for enabling the I2C connection to the clock generator.  Resistors R121 and R122 will connect the I2C.   Note that the clock generator provides the correct clock frequencies by default and does not need to be programmed.

Regards, Bill

Sorry, I did not short R120 and R121 as stated, but R121 and R122

I double checked.

Sorry for the mistake in my first post.

I just want to test I2C communication with the Serdes board by reading the Revision ID of the PLL chip

This is just for initial debugging purpose:

in the future I will need to access SMCLK and SMDAT on the PCIe connector to send data to a board that will be connected to the PCIe slot, but at the moment the board has not been developed yet.

I hope this clarifies my intent

I think you are referring to jumper J44 and J45

They are already set to the correct position (left+center)

Hi Genesio,

You have misunderstood my comment.  The MCU_I2C is not functional on the GP EVM.  You will need to use the SoC I2C1 if you want to communicate with the clock generator. 

Regards, Bill

Dear Bill,

thanks for the clarification.

By "not functional" you mean that it is not enabled in software (Arago) or that the malfunction is in the hardware part?

I set J44 and J45 to I2C1_SDL and I2C1_SDA position

The I booted Arago and tried to find all available I2C devices:

Unfortunately I am still not able to find the device I am looking for, and now I get errors from device /dev/i2c-1

Please check following `i2cdetect` dump:

root@am65xx-evm:/dev# i2cdetect -y -a -r 0
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- UU -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: 50 51 -- -- 54 -- -- -- -- -- -- -- -- -- -- -- 
60: 60 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
root@am65xx-evm:/dev# i2cdetect -y -a -r 1
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00: [  208.313811] omap_i2c 40b00000.i2c: timeout waiting for bus ready
-- [  209.325823] omap_i2c 40b00000.i2c: timeout waiting for bus ready
-- [  210.337823] omap_i2c 40b00000.i2c: timeout waiting for bus ready
-- [  211.349845] omap_i2c 40b00000.i2c: timeout waiting for bus ready
-- [  212.361846] omap_i2c 40b00000.i2c: timeout waiting for bus ready
-- [  213.373855] omap_i2c 40b00000.i2c: timeout waiting for bus ready
-- [  214.385875] omap_i2c 40b00000.i2c: timeout waiting for bus ready
-- [  215.397875] omap_i2c 40b00000.i2c: timeout waiting for bus ready
-- ^C[  216.409893] omap_i2c 40b00000.i2c: timeout waiting for bus ready

root@am65xx-evm:/dev# i2cdetect -y -a -r 2
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- UU -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- 57 -- -- -- -- -- -- -- -- 
60: 60 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
root@am65xx-evm:/dev# i2cdetect -y -a -r 3
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- 52 -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
root@am65xx-evm:/dev# i2cdetect -y -a -r 4
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: 40 41 42 43 44 45 46 47 48 49 -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
root@am65xx-evm:/dev# i2cdetect -y -a -r 5
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00: [  226.154005] omap_i2c 2030000.i2c: controller timed out
-- [  227.209997] omap_i2c 2030000.i2c: controller timed out
-- [  228.265995] omap_i2c 2030000.i2c: controller timed out
-- ^C[  229.322049] omap_i2c 2030000.i2c: controller timed out

Hello Bill,

I am still not able to find a workaround for this issue.

I am not sure if there is an hardware bug in the development board or the issue is in the software

Could you please help me solving this problem?

Genesio

Hi Genesio,

I am not sure if we have ever attempted to access that device using the I2C interface.  I will have to get one of the software support team members involved.  I will forward your question to them and get back to you as soon as possible.

Regards, Bill

Hi Genesio,

I am wondering if the MCU_I2C is enabled in the Uboot and Linux device-tree node. By default, we do not enable the MCU_I2C bus but I have attached a reference patch that shows how you could enable the bus. With regards to the pin mux, please use the pin mux tool to specific the bus pins.

Regards,
Krunal

diff --git a/arch/arm/dts/k3-am654-base-board.dts b/arch/arm/dts/k3-am654-base-board.dts
index 08a9c42199..e5da25aea4 100644
--- a/arch/arm/dts/k3-am654-base-board.dts
+++ b/arch/arm/dts/k3-am654-base-board.dts
@@ -49,6 +49,13 @@
 		>;
 	};
 
+	mcu_i2c0_pins_default: mcu-i2c0-pins-default {
+		pinctrl-single,pins = <
+			AM65X_WKUP_IOPAD(0x00e8, PIN_INPUT, 0) /* (AD8) MCU_I2C0_SCL */
+			AM65X_WKUP_IOPAD(0x00ec, PIN_INPUT, 0) /* (AD7) MCU_I2C0_SDA */
+		>;
+	};
+
 	mcu_fss0_ospi0_pins_default: mcu-fss0-ospi0-pins-default {
 		pinctrl-single,pins = <
 			AM65X_WKUP_IOPAD(0x0000, PIN_OUTPUT, 0) /* (V1) MCU_OSPI0_CLK */
@@ -164,6 +171,12 @@
 	};
 };
 
+&mcu_i2c0 {
+	pinctrl-names = "default";
+	pinctrl-0 = <&mcu_i2c0_pins_default>;
+	clock-frequency = <400000>;
+};
+
 &main_i2c0 {
 	pinctrl-names = "default";
 	pinctrl-0 = <&main_i2c0_pins_default>;