AM3356: Standby/LPM mode configuration

Takayuki Miyazaki

Part Number: AM3356

Hi Experts,

Customer is developing their system with AM3356/TPS65910AA1RSLR.

Customer would like to support Sleep/Low power mode (however, Wake-up function is possible with the signal from the terminal) and reduce the current consumption as much as possible. Therefore, customer is looking for detail LPM configuration setting, Guidelines and manuals for LPM mode. Could you share them, please?

Also, customer would like to decrease PMIC’s voltage during LPM mode. Customer found the this URL(http://tomoyo.osdn.jp/cgi-bin/lxr/source/Documentation/devicetree/bindings/mfd/tps65910.txt#L3). Customer is asking TI that customer should change those regulators-configuration on this URL. I’m not sure if it is possible. It will be appreciated if you will share Expert’s advice/comments on this.

Best regards,

Miyazaki

over 4 years ago

0 Bin Liu over 4 years ago

TI__Guru**** 150201 points

Hi Miyazaki,

What software does the customer use? TI Processor SDK Linux or RTOS?

0 Takayuki Miyazaki over 4 years ago in reply to Bin Liu

TI__Genius 10120 points

Hi Bin,

Customer is using TI Processor SDK Linux.

Best regards, Miyazaki

0 Bin Liu over 4 years ago in reply to Takayuki Miyazaki

TI__Guru**** 150201 points

Hi Miyazaki,

System Suspsend and Resume is already implemented in Processor SDK Linux, customers can directly use it in their projects. Please refer to the following documentation for details..

https://software-dl.ti.com/processor-sdk-linux/esd/docs/06_03_00_106/AM335X/linux/Foundational_Components/Kernel/Kernel_Drivers/Power_Management.html#power-management-on-am335-and-am437

0 Takayuki Miyazaki over 4 years ago in reply to Bin Liu

TI__Genius 10120 points

Hi Bin,

Thank you for your help. I shared your comments with customer. I'd like to wait for their feedback for a while.

Best regards, Miyazaki

0 Takayuki Miyazaki over 4 years ago in reply to Takayuki Miyazaki

TI__Genius 10120 points

Hello Bin,

Customer is referring the user guide which you shared with us. Customer is considering the output voltage of PMIC can be controlled by dts modification at Standby/suspend state. it means, customer is considering that they should modify parts of "regulator-always-on" in device tree file. Customer is hoping to get TI Expert's comments .Can I have your Expert's advice/comments on this, please?

I attached customer's dts file(am335x-itcont.zip).

Best regards,

Miyazaki

0 Bin Liu over 4 years ago in reply to Takayuki Miyazaki

TI__Guru**** 150201 points

Miyazaki,

I am not sure I fully understand the customer's query, but to set the PMIC regulator's output voltage, it can be done in device tree. Please see the AM335x GP EVM dts am335x-evm.dts '&tps' node, for example, 'vdd1_reg' node:

671                 vdd1_reg: regulator@2 {                                         
672                         /* VDD_MPU voltage limits 0.95V - 1.26V with +/-4% tolerance */ 
673                         regulator-name = "vdd_mpu";                             
674                         regulator-min-microvolt = <912500>;                     
675                         regulator-max-microvolt = <1351500>;                    
676                         regulator-boot-on;                                      
677                         regulator-always-on;                                    
678                 };

0 Takayuki Miyazaki over 4 years ago in reply to Bin Liu

TI__Genius 10120 points

Hi Bin,

Thanks for your comments. I tried to translate customer's inquiry. I'm sorry.. I shared your comments with customer. I'd like to waiting for their feedback for a while.

Best regards,

Miyazaki

0 Takayuki Miyazaki over 4 years ago in reply to Takayuki Miyazaki

TI__Genius 10120 points

Hi Bin,

I received customer's comments. Customer wants to reduce PMIC's voltage in Standby mode, (Tt means, customer wants to reduce power consumption as much as possible). Regarding PMIC's voltage in Standby mode, which descriptions should customer refer to?

If customer should refer other descriptions, could you elaborate it, please?

I'm not sure how much the power consumption would b reduced when PMIC's voltage is decreased. Can we also have your Expert's advice/comments on this, please?

Best regards,

Miyazaki

0 Bin Liu over 4 years ago in reply to Takayuki Miyazaki

TI__Guru**** 150201 points

Miyazaki,

As in the am335x-evm.dts snippet I posted above, each PMIC regulator's lowest voltage is set by kernel DT property "regulator-min-microvolt".

Customers can set this property for each power rail based on the AM335X Datasheet to reduce power consumption.

-Bin.

0 Takayuki Miyazaki over 4 years ago in reply to Bin Liu

TI__Genius 10120 points

Hi Bin,

Please allow me to confirm it a little bit. It means, "regulator-min-microvolt". Value was set at Standby mode. Is that correct?

I tried to check it, I was not able to reach it..

Best regards,

Miyazaki

0 Bin Liu over 4 years ago in reply to Takayuki Miyazaki

TI__Guru**** 150201 points

Hi Miyazaki,

"regulator-min-microvolt' set the lowest voltage allowed on the regulator for ALL cases. I will have to check the kernel code to see if Standby mode adjust the voltage to the min value. I will get you back in a few days.

0 Bin Liu over 4 years ago

TI__Guru**** 150201 points

Hi Miyazaki,

I have confirmed with our power expert, when AM335x enters or leaves standby/LPM mode, the CM3 firmware manages the OPPs, so the PMIC voltages have been adjusted accordingly during the mode transitions, so there is impossible to further decrease the PIMC voltages.

0 Takayuki Miyazaki over 4 years ago in reply to Bin Liu

TI__Genius 10120 points

Hi Bin,

I got it.. I received the result for this evaluation. Customer is reporting PMIC voltage was not changed even if AM335x entered or left standby/LPM mode.. I shared your Expert's comments honestly.

Thanks for your clarification.

Best regards, Miyazaki

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AM3356: Standby/LPM mode configuration