AM625: LVDS driver capabilities

Jhon Q

Part Number: AM625

Hi,

About LVDS driver capabilities of the AM62x,

In order to make LVDS interface working we have to clear bit 31 (Selects LVDS IO Bias Voltage) in registers 0x00108600, 0x00108604, 0x00108608, 0x0010860C, 0x00108610. Is it possible to configure this bit via dts file? Will appreciate your support on the above.

Thanks,

Jhon

over 3 years ago

0 Krunal Bhargav34 over 3 years ago

TI__Mastermind 45015 points

Hello,

Are you referring to the following patch: https://git.ti.com/cgit/ti-linux-kernel/ti-linux-kernel/commit/?h=ti-linux-5.10.y&id=7d7fc545dadff8be9c36d02c21a05dc1feb9817b

Regards,
Krunal

0 Jhon Q over 3 years ago in reply to Krunal Bhargav34

Prodigy 245 points

Hi,

The patch you referred to is for modifying bit 8 OLDI_BG_PWRDN while we are interested in modifying bit 31 as mentioned above.

How can we do this via the device tree?

Jhon

0 Krunal Bhargav34 over 3 years ago in reply to Jhon Q

TI__Mastermind 45015 points

Hello Jhon,

I am curious why your setup requires bit31 to be cleared. On our LVDS setup, we did not have to perform the same and our IP developer recommended to leave the values in default state. In terms of modifying the values, you have two options:

1. Create a uEnv.txt file and add something like: uenvcmd=if run check_psdk_setup; then echo "Already setup."; else run do_psdk_setup; mw.b ${loadaddr} 0 1; fatwrite mmc 1:1 ${loadaddr} .psdk_setup 1; reset; fi; mw.l <0xreg> <0xvalue>; mw.l <0xreg> <0xvalue>

2. Modify the register value in the DSS driver, similar to what we did for bit 8 in the above patch.

Regards,
Krunal

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AM625: LVDS driver capabilities