2009-06-29 04:35:08     LCD flicker during USB read

Document created by Aaronwu Employee on Aug 15, 2013
Version 1Show Document
  • View in full screen mode

2009-06-29 04:35:08     LCD flicker during USB read

Narendra Nath (INDIA)

Message: 76457   

 

Hi

 

     I am using ISP1761 as USB host in my application.I am able to mount and browse the USB and display USB contents in LCD which is interfaced to PPI  of LCD.8 bit PPI 2D DMA is configured for LCD data transfer and in ISR data is copied into DMA buffer.Here the issue i am facing is during playback of mp3 somngs  when ever USB data is read continuosly LCD is flickering. I want to know if interrupts are masked in USB driver for a quite long period of time.

 

Narendra

QuoteReplyEditDelete

 

 

2009-06-29 07:08:32     Re: LCD flicker during USB read

Robin Getz (UNITED STATES)

Message: 76462   

 

Narendra:

 

What version of software are you using?

 

-Robin

QuoteReplyEditDelete

 

 

2009-07-08 02:05:52     Re: LCD flicker during USB read

Narendra Nath (INDIA)

Message: 76906   

 

Hi Robin

 

        Sorry for late reply.I am using 2008 R1.5 Distribution with USB(pehcd driver) downloaded and included as module.

 

I feel during USB read inteerupts are getting masked..which is causing My ppi line interrupt to be missed.Kindly suggest me an alternative

 

Narendra

QuoteReplyEditDelete

 

 

2009-07-08 02:16:20     Re: LCD flicker during USB read

Robin Getz (UNITED STATES)

Message: 76907   

 

Narendra:

 

It is not in the 2008R1 branch, but you should be able to add something like:

 

  blackfin.uclinux.org/gf/project/linux-kernel/scmsvn/?action=browse&path=%2F&view=rev&revision=5174

 

to help out.

 

-Robin

QuoteReplyEditDelete

 

 

2009-07-08 06:13:19     Re: LCD flicker during USB read

Narendra Nath (INDIA)

Message: 76925   

 

Hi Robin

 

We have added the ins patch for low latency, infact we have even commented CLI and STI commands ,but still when ever USB read happens LCD is getting flickering(Indicating we are missing some LCD interrupts).Could you help us to procedd further.

 

Narendra

QuoteReplyEditDelete

 

 

2009-07-08 08:00:17     Re: LCD flicker during USB read

Robin Getz (UNITED STATES)

Message: 76927   

 

Narendra:

 

Commenting out the CLI/STI instructions is just plain wrong - it will cause other problems - like USB data being incorrect.

 

-Robin

QuoteReplyEditDelete

 

 

2009-07-08 23:02:39     Re: LCD flicker during USB read

Sonic Zhang (CHINA)

Message: 76937   

 

which blackfin chip do you use? You may raise the priority of PPI DMA.

QuoteReplyEditDelete

 

 

2009-07-09 11:00:25     Re: LCD flicker during USB read

Robin Getz (UNITED STATES)

Message: 76972   

 

Natendra:

 

There are PPI troubleshooting topics in the wiki - did you look there?

 

https://docs.blackfin.uclinux.org/doku.php?id=ppi#troubleshooting

QuoteReplyEditDelete

 

 

2009-07-15 02:27:29     Re: LCD flicker during USB read

Narendra Nath (INDIA)

Message: 77287   

 

Hi Robin/Sonic

 

          I am using Bf533 processor based hardware with a 320x240 LCD inerfaced to PPI of Blackfin and ISP1761  interfaced to AMS 3 bank.I am using 2008 r1.5 distribution with Linux 2.6 kernel and i have downlaoded the ISP1761 USB driver from SVN.PPI DMA interrupt is configured for each line.Timer 1 and Timer 2  generate the Frame syncs.Regarding AMS bank settings i am using default (0xffc2 0xffc2) settings.

 

I have gone thorugh PPI handling techniques.Thanks for the same.Right now My PPI interrupt is of higher priority than that of USB GPIO interrupt.Also i have enabled DMA higher priority than core in EBIU settings.After making all the changes i checked if i am really missing any interrupts and i found When ever i invoke a USB read of 512 bytes i will miss around 6 to 7 PPI (line)interrupts because of which LCD is flickering.So please suggest  if there is any other way to solve this issue

 

Best Regards

 

Narendra

QuoteReplyEditDelete

 

 

2009-07-15 05:29:34     Re: LCD flicker during USB read

Michael Hennerich (GERMANY)

Message: 77327    First of all reduce the AMS3 timings to a minimum.

Check the ISP1761 Datasheet for timing specs.

FFC2 is the maximum!!!

 

I wonder why you use Line Interrupts? - The /dev/fb drivers I know don't use Interrupts at all.

 

-Michael

QuoteReplyEditDelete

 

 

2009-07-15 07:39:47     Re: LCD flicker during USB read

Michael Hennerich (GERMANY)

Message: 77349    Can you try with 0x66C4?

The ISP1760 should even work with much less wait states - however on my

HW I see error pop up.

Attachments

    Outcomes