Linux/AM3354: LCD Sync lost issue

Achim Kanert44

Prodigy 80 points

Part Number: AM3354

Tool/software: Linux

Hi,

we are getting periodically sync lost errors from the tilcdc driver.

The sync lost appears without any FIFO_UNDERRUN, so priority adjusting does not help.

The workaround with disable/enable lcdc prevents from stalling the whole system, but the display flickers shortly.

Is there any explanation for this problem or something we can try to fix this?

Regards,

Achim Kanert

over 7 years ago

0 Biser Gatchev-XID over 7 years ago

TI__Guru**** 393215 points

Hi,

What is the Linux version you use?

0 Achim Kanert44 over 7 years ago in reply to Biser Gatchev-XID

Prodigy 80 points

Hi,

we are using the last 4.1.13 TI kernel.

With patches to recover on sync lost interrupt flodding.

Regards,

Achim Kanert

0 Biser Gatchev-XID over 7 years ago in reply to Achim Kanert44

TI__Guru**** 393215 points

Thanks. I have notified the software team. They will respond here.

0 Manisha Agrawal over 7 years ago in reply to Biser Gatchev-XID

TI__Mastermind 22946 points

Is this on your custom board or AM335x GP EVM/Beagle Bone board? Please share all the information on hardware and software setup, custom modifications etc. Also share dmesg and lcdc logs.

0 Achim Kanert44 over 7 years ago in reply to Manisha Agrawal

Prodigy 80 points

Yes this is a custom board, but this should not influence the internal vsync signal. the display only uses DE signal.

So this problem seems to be internal to the soc.

Regards,

0 Manisha Agrawal over 7 years ago in reply to Achim Kanert44

TI__Mastermind 22946 points

May be the driver is not getting enough cycles timely to update the DMA pointers update and is getting starved to serve it timely and hence causing the sync lost error.

0 Achim Kanert44 over 7 years ago in reply to Manisha Agrawal

Prodigy 80 points

Hi,

do you have any idea how to fix this (reduce display refreshrate, change priorities) ?

Regards,

Achim

0 Manisha Agrawal over 7 years ago in reply to Achim Kanert44

TI__Mastermind 22946 points

I would suggest to migrate to kernel version 4.9 as many fixes has happened in the tilcdc driver since 4.1 version and then take the debugging from there.

Processors

Processors forum

Linux/AM3354: LCD Sync lost issue