Linux/AM3352: LCD issues

Rohit Khatri

Part Number: AM3352

Tool/software: Linux

Hi,

We are ported new sdk based on kernel 4.4.12 but facing issue related to brightness of LCD.

Before that our product was running on kernel 3.2.0 and now we have ported to 4.4.12. But with this new kernel version, brightness of LCD is changing any time even on run time or start up time.

It has 320x280 dimensions and working at 6.5 MHz frequency. Brightness control is based on pwm, nut we are keeping it constant at 90% duty cycle.

We have also verified that pwm/ecap0 pin as gpio to keep brightness constant, but issue is still same. Platform data provided in board file of older kernel and dts file of new kernel is identical.

So, why this is happening.

Best Regards

Rohit Khatri

over 8 years ago

0 Biser Gatchev-XID over 8 years ago

TI__Guru**** 393215 points

Hi,

Kernel v4.4.12 is several releases old. Have you tried with the latest SDK (software-dl.ti.com/.../index_FDS.html) Also, have you measured the LCD signals to verify they are correct?

0 Rohit Khatri over 8 years ago in reply to Biser Gatchev-XID

Intellectual 990 points

Hi,

Yes we have verified lcd signals and it looks fine.

We have one more product in which lcd is 480x320 and this same software is working without any problem.

We have also dumped frame buffer, it is ideal and as required. But problem is in backlight control. It is not able to work other then first and last level of brighness specified in dts file. It remains in two state only, either zero or full.

BR,

Rohit Khatri

0 Biser Gatchev-XID over 8 years ago in reply to Rohit Khatri

TI__Guru**** 393215 points

See these wikis: processors.wiki.ti.com/.../Linux_Core_PWM_User's_Guide
processors.wiki.ti.com/.../AM335x_PWM_Driver's_Guide

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Linux/AM3352: LCD issues