PROCESSOR-SDK-AM62X: DTS backlight setting problem

Hello Daniel, 

Thank you for the query.

Is the query related to any of the SK ? Help me understand the SK you are using.

Regards,

Sreenivasa

Hi Sreenivasa

BR2_LINUX_KERNEL_CUSTOM_REPO_VERSION="10.01.10"

If two PWMs are to use different frequencies, do they need to use different pwm such as epwm0 epwm1?
Because it doesn't make sense to be limited to a fixed frequency by the backlight, so the pwm buzzer can't change the sound (only one sound)

enable-gpios is mainly to know what its function is, so that we can consider whether it is necessary to configure an additional gpio for it

Thanks

Daniel

Hello Daniel, 

Thank you.

Daniel Cheng1 said:

If two PWMs are to use different frequencies, do they need to use different pwm such as epwm0 epwm1?

This should work

Daniel Cheng1 said:

Because it doesn't make sense to be limited to a fixed frequency by the backlight, so the pwm buzzer can't change the sound (only one sound)

enable-gpios is mainly to know what its function is, so that we can consider whether it is necessary to configure an additional gpio for it

Not sure i understand your inputs. Please confirm if you have some query or was this a statement.

Regards,

Sreenivasa

Hi Sreenivasa

Customers want to know whether backlight control must be paired with a gpio to control the backlight brightness?

Thanks

Daniel

Hello Daniel, 

Thank you.

Daniel Cheng1 said:

Customers want to know whether backlight control must be paired with a gpio to control the backlight brightness?

Please elaborate your query.

Regards,

Sreenivasa

Hi Sreenivasa

Please let us know, whether we set "enable-gpios" property in backlight node or NOT, what's the difference to the backlight function?

in the previous product am571x, we didn't have this gpio, therefore we need to know the pros and cons. is it clear for you?

Thanks

Hello Scott, 

Thank you.

I am not sure i understand the query.

Can you please describe the issue including the schematics being referenced for discussion.

Kallikuppa Sreenivasa said:

Is the query related to any of the SK ? Help me understand the SK you are using.

Please clarify.

Regards,

Sreenivasa

Hi Sreenivasa

what do you mean SK? am6234?

BR2_LINUX_KERNEL_CUSTOM_REPO_VERSION="10.01.10"

BR2_LINUX_KERNEL_INTREE_DTS_NAME="ti/k3-am625-sk"

https://software-dl.ti.com/processor-sdk-linux/esd/AM62X/10_01_10_04/exports/docs/linux/Foundational_Components/Kernel/Kernel_Drivers/PWM.html

it did not show what enable-gpios is and i can see other threads are using it.

Thanks

Hello Scott, 

Thank you.

Let me review the inputs.

Scott Lin2 said:

what do you mean SK? am6234?

SK means starter kit. I was checking if you are refereeing to a custom board or starter kit.

Regards,

Sreenivasa

Our custom board design is based on SK-AM62B-P1.

Hello Scott, 

Thank you.

In case the circuit we are discussing in on the SK please point me to the section.

if this is a custom implementation, please share a PDF schematic of the section.

Regards,

Sreenivasa

Hello Scott, 

I am not sure i understand the query regarding the GPIO.

The GPIO connects to an ANDing logic that enables the LED driver operation.

The default value is pulldown (disable)

You should be pulling the input high or configuring the GPIO for be output and level to be high to enable.

Regards,

Sreenivasa

Hi Sreenivasa

We want to know the functionality of this ("enable-gpios") SW configuration in device tree.

NOT, how to enable backlight........

thanks

Hello Scott,

Thank you.

Let me check internally and assign to a software expert.

Regards,

Sreenivasa

Hello Scott,

Please share the development environment details that you are using.

Regards,

Sreenivasa

Hello Scott, 

Apologies, i found the info.

BR2_LINUX_KERNEL_CUSTOM_REPO_VERSION="10.01.10"

Regards,

Sreenivasa

Hi Sreenivasa

Please help to assign the ticket. thanks

Hello Scott,

Thank you for following, the thread has been assigned for the expert to support.

Regards,

Sreenivasa

Hi Scott,
Please take a look at the following example:
https://git.ti.com/cgit/ti-linux-kernel/ti-linux-kernel/tree/arch/arm64/boot/dts/ti/k3-am625-beagleplay.dts?h=ti-linux-6.12.y#n643 
https://git.ti.com/cgit/ti-linux-kernel/ti-linux-kernel/tree/arch/arm64/boot/dts/ti/k3-am625-beagleplay-lincolntech-lcd185-panel.dtso?h=ti-linux-6.12.y#n24 

Enable gpio basically enables the BL_EN_3V3 gpio line which on this (example) beagleplay board is routed through OLDI pins to the display panel.

Can we assign our GPIO_LED_EN pin to this backlight node 

like -> enable-gpios = <&main_gpio0 34 GPIO_ACTIVE_HIGH>;

Hello Scott,

If your custom hardware is connecting GPIO0_34 to the panel, there shouldn't be any issues with assigning GPIO0_34.

You can check the datasheet Pin Attributes to make sure the GPIO0_34 pin is not being used by another peripheral: https://www.ti.com/lit/gpn/am625

The Beagleplay documentation gives more information about their board has implemented it: git.beagleboard.org/.../BeaglePlay_sch.pdf

Best Regards,

Anshu