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Parallella Community • View topic - How to use the DMA engine

How to use the DMA engine

Any technical questions about the Epiphany chip and Parallella HW Platform.

Moderator: aolofsson

How to use the DMA engine

Postby Richardye » Wed Nov 11, 2015 2:34 pm

Hi Guys,

Here I got quite confused about the DMA control in the epiphany side. Hope someone could help me ...

typedef struct
{
unsigned config;
unsigned inner_stride;
unsigned count;
unsigned outer_stride;
void *src_addr;
void *dst_addr;
} e_dma_desc_t;

Above is the declaration for the e_dma_desc_t.

The questions are ,

1. What does the inner & outer stride, count stands for ? If I would like to copy a char array of size 1024, how whould I set these values ?

2. How can I start the DMA transfer ? Using int e_dma_start(e_dma_desc_t *descriptor, e_dma_id_t chan) or e_dma_copy(void *dst, void *src, size_t bytes) ?

Hope some one could help me, this really bothers me !!!!

Thanks,
Richard
Richardye
 
Posts: 8
Joined: Mon Sep 07, 2015 6:30 pm

Re: How to use the DMA engine

Postby jar » Thu Nov 12, 2015 3:43 pm

User avatar
jar
 
Posts: 295
Joined: Mon Dec 17, 2012 3:27 am

Re: How to use the DMA engine

Postby Richardye » Sun Nov 15, 2015 9:51 pm

Hi Jar,

Thank you very much! Now the DMA thing is much clearer. Thank you :D
Richardye
 
Posts: 8
Joined: Mon Sep 07, 2015 6:30 pm


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