Re: [ts-7000] DMA with SSP on TS7400

[Abid Rashid <>]

 

Kmalloc returned addresses need to be mapped to the bus addresses.

Use

bus_addr = virt_to_bus(virt_addr/*returned from kmalloc*/);

address as the dma destination.

Hope it would help

br,

Abid

--- On Mon, 3/15/10, pakorn_0608 <> wrote:

From: pakorn_0608 <>
Subject: [ts-7000] DMA with SSP on TS7400
To:
Date: Monday, March 15, 2010, 3:21 AM

 

Dear members,

I'm use DMA on M2M mode with SSP, both of SSPTx and SSPRx for each channel.

I have a bit problem with data that transmit and receive from SSP.

I use "kmalloc" to get allocate memory address and i write some data into that address.
I can write and read correctly by using "printk".

I'm also use it with SSPDR for transmit data from SPI by "outl" command, data come out from SSPTx with clock sync correctly.

Anyway,It's wrong when i'm using with DMA register.

For example, DMA M2M0 using with SSPtx, I set DMA register, source register with address from kmalloc "0xd120_10eo" , destination address SSPDR "0x808A_0008" and BCR by 3.

There are data come out from SSPtx but it is not right value that it should be in memory address shown by "printk".

Could someone have some suggest to me for using DMA with SSP for 7400 board?

************ *******
example with some coding:
************ *******

/* I write it for kernel module*/
...
char *buffer_dma[ MAX_EP93XX_ DMA_M2M_CHANNELS ];
.
.
.
buffer_dma[0] = kmalloc( size , GFP_KERNEL|GFP_ DMA); /* example size is 10*/

for(i=0;i<10; i++)
{
buffer_dma[0] [i] = i*10;

printk("Address of buffer_dma[0] [%d] = 0x%lx\n",i,( unsigned long)&buffer_ dma[0][i] );
printk("Value of buffer_dma[0] [%d] = %d\n",i,buffer_ dma[0][i] );
}

/*
I print this value for show address and value
my address for buffer_dma[0] [0] is "0xd120_10eo" and value is 0
next, address for buffer_dma[0] [1] is "0xd120_10e1" and value is 10... and other value is shown correctly.

I also use with SSP

*/

for(i=0;i<10; i++)
{
outl(buffer_ dma[0][i] , SSPDR );
}

/*
I'm set SSP 8 bit,
data come out from SSPTx is correctly , compare bit by bit with ssp_clock

next i'm usongit with DMA M2M for SSPTx

*/

outl(&buffer_ dma[0][0] , m2m_channel[ channel]. base + M2M_SAR_BASE0) ;
outl( SSPDR , m2m_channel[ channel]. base + M2M_DAR_BASE0) ;
outl(3 , m2m_channel[ channel]. base + M2M_BCR0);

/*
After that i'm enable DMA
my data that come out from SSPTx is wrong all,
even i change data in my buffer_dma[0] [i] on above
data come out from SSPTx is still the same value.
It's not match with it should be in memory address
*/

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