2010-04-20 02:14:40     about mdma0/1 descriptor question

Document created by Aaronwu Employee on Aug 21, 2013
Version 1Show Document
  • View in full screen mode

2010-04-20 02:14:40     about mdma0/1 descriptor question

macgrady tracy (CHINA)

Message: 88610   

 

hi:

I am getting mpeg4 encoder from ffmpeg project, and now this encoder

can run about 20fps in bf531 platform. But the encoder can only support

format of yuv420.

But my sensor capture the format of uyvy422.

And now, my idea is to use mdma to carry uyvy422 to yuv420 in the

kernel space.

After my study of the structure of the dma in bf531, i know the BF531's

MDMA has some method of carry data: stop mode, array mode, large descriptor,

small descriptor, but I can't find some example of mdma0/1 in the linux

kernal!

 

My question:

for example:

If i want carry uyvy422(CIF(352*288)) to yuv420(CIF),

which mdma method should i choose?

if i choose large descriptor mdma mode, how can i configure the mdma param.

I want use destination mdma0 to get yuv420,

     and   use source mdma0 to put uyvy420.

Any suggestion example or some code is best!

thanks!!!

QuoteReplyEditDelete

 

 

2010-04-20 02:28:07     Re: about mdma0/1 descriptor question

Mike Frysinger (UNITED STATES)

Message: 88611   

 

please review the documentation:

  docs.blackfin.uclinux.org/doku.php?id=dma_systems

  docs.blackfin.uclinux.org/doku.php?id=linux-kernel:drivers:bfin-dma

QuoteReplyEditDelete

 

 

2010-04-20 04:14:34     Re: about mdma0/1 descriptor question

macgrady tracy (CHINA)

Message: 88627   

 

thank you for your reply

but refer to the doc, i can't get how to use

large descriptor or small descriptor usage.

is there anyone can give me some source code?

thanks!!!

QuoteReplyEditDelete

 

 

2010-04-20 04:26:18     Re: about mdma0/1 descriptor question

Mike Frysinger (UNITED STATES)

Message: 88630   

 

we focus on the glue between Linux and the hardware, not generally on teaching people how to use the hardware.  as such, there are no examples of that.  read the DMA chapter of the HRM.

Attachments

    Outcomes