DM8148/AM3874 LCD Panel Timings

David Paden

Expert 1945 points

Other Parts Discussed in Thread: AM3517

Hello all,

Have been looking for a while and cannot find any answer...where are the LCD panel timings defined for the DM8148 Eval Kit? I need to adjust them for a custom display panel.

On the AM3517 (and most other embedded platforms), the display panel settings are either embedded in the board sources or in the drivers/video folder, but I can't find anything regarding the Hannstar display...

Thanks

over 13 years ago

0 HardikShah over 13 years ago

TI__Mastermind 20245 points

Hi,

You can change timings using following sysfs entry. "/sys/devices/platform/vpss/display1/timings" Please refer to video driver userguide for more details. Video driver userguide could be found at http://processors.wiki.ti.com/index.php/DM814X_AM387X_VPSS_Video_Driver_User_Guide

Regards,

Hardik Shah

0 David Paden over 13 years ago in reply to HardikShah

Expert 1945 points

Unfortunately, the timings are not changing when adjusting the sysfs entry (already tried it). This method worked fine on AM3517, but is not working on DM8148 VPSS driver.

I found the timings in a "global" table in the VPSS driver. I don't think this is an appropriate place to define specific LCD panel timings, but it works I suppose. I was able to adjust as necessary using this entry.

Thanks,

0 Steve Clynes over 13 years ago in reply to David Paden

TI__Mastermind 43875 points

David,

You must disable the display before changing parameters I believe.

You are correct that hard coded into the driver is not the correct place for timing changes, which is why the timings sysfs entry was created.

It might be that you are not using the latest PSP release which supports the timing entry.

Do you get any error message when you try to use the sysfs entry to change the timing parameters?

Hard coded values do have some benefits since they allow enumerated video settings, but discrete timing control is also important.

BR,

Steve

0 Muthukrishnan Chinnasamy over 13 years ago in reply to Steve Clynes

Prodigy 40 points

Steve,

I am facing similar problem for changing the LCD display parameters for DM8148 device under WinCE7 environment.

Our HDMI out is working, but whatever changes we make to the VIDEO_OUT PLLs, LCD parameters entries in the

code, nothing comes up on the LCD video port. What do we need to do differently..?? Where to change LCD display parameters in WinCE env ?

Interestingly, under Linux LCD display is working so the HW is fine. We had built our own board. Please help or point to the right people

who knows all about 8148 display LCD driver programming.

Regards,

/Muthu

0 Steve Clynes over 13 years ago in reply to Muthukrishnan Chinnasamy

TI__Mastermind 43875 points

Muthu,

Unfortunately I am not familiar with WinCE at all, so can't be much help.

I will try to get someone who knows WinCE to help.

BR,

Steve

0 Steve Clynes over 13 years ago in reply to Steve Clynes

TI__Mastermind 43875 points

Which 3rd party did you work with for your WinCE porting? Your 3rd party should be able to help with this.

BR,

Steve

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DM8148/AM3874 LCD Panel Timings