Hi
I ported successfully the Linux 2.6.19 kernel to our PPC405GPr based board and
mostly everything just works as it should.
As an example I tried to make a small example program to use memory to memory
DMA and failed miserably. I used the ppc4xx_*dma function, which are not
referenced anywhere in a stock 2.6.19.1 kernel in the following function:
void dma_mem_to_mem(void *src, void *dst, unsigned int length,
unsigned int use_interrupt)
{
int res = 0;
memset((char *)&p_init, sizeof(p_init), 0);
p_init.polarity = 0;
p_init.pwidth = PW_8;
res = ppc4xx_init_dma_channel(DMA_NR, &p_init);
if (res) {
printk("%32s: nit_dma_channel return %d %d bytes dest %p\n",
__FUNCTION__, res, length, dst);
}
res = ppc4xx_clr_dma_status(DMA_NR);
if (res) {
printk("%32s: ppc4xx_clr_dma_status %d\n", __FUNCTION__, res);
}
ppc4xx_set_dma_mode(DMA_NR, DMA_MODE_MM);
ppc4xx_set_src_addr(DMA_NR, src);
ppc4xx_set_dst_addr(DMA_NR, dst);
ppc4xx_set_dma_count(DMA_NR, length);
ppc4xx_enable_dma(DMA_NR);
if (use_interrupt) {
res = ppc4xx_enable_dma_interrupt(DMA_NR);
} else {
res = ppc4xx_disable_dma_interrupt(DMA_NR);
}
if (res) {
printk("%32s: en/disable_dma_interrupt %d return %d per %d\n",
__FUNCTION__, use_interrupt, res,
ppc4xx_get_peripheral_width(DMA_NR));
}
}
However the destination memory never changed, even when calling repeatedly
ppc4xx_get_dma_residu function correctly return first something between
length and 0 and finally 0.
Any hints would be appreciated. As googleing around didn't allow me to find an
answer.
Also I am a little confused as I cannot see how something dma_alloc_coherent
should work on a PPC4xx board.
Best regards
--
Niklaus Giger
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