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

Narendra Nath (INDIA)

Message: 76457

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

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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

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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

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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

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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

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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

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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.

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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

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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

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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

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