On Thu, Oct 29, 2009 at 9:44 PM, Sergey Lapin <slapinid@xxxxxxxxx> wrote:
> Hi, all!
>
> I need to transfer block of data using sDMA from memory address
> to RFBI_PARAM FIFO, so to put that into display module.
>
> I do this like this:
>
> /* DMA */
> #define RFBI_BASE 0x48050800
> #define RFBI_PARAM 0x0050
> static void configure_dma(int dma_ch, u32 data, int size)
> {
> int nblk;
> omap_set_dma_dest_params(dma_ch, 0, OMAP_DMA_AMODE_CONSTANT,
> (RFBI_BASE + RFBI_PARAM), 0, 0);
> omap_set_dma_src_params(dma_ch, 0, OMAP_DMA_AMODE_POST_INC,
> data, 0, 0);
> nblk = (size + PAGE_SIZE - 1) / PAGE_SIZE;
> omap_set_dma_transfer_params(dma_ch, OMAP_DMA_DATA_TYPE_S8,
> PAGE_SIZE, nblk, OMAP_DMA_SYNC_FRAME, 0, 0);
> omap_start_dma(dma_ch);
> }
Just making sure, do you want to use DMA to configure just a single
register ? According to your code, you want to transfer "data" to the
configuration register called RFBI_PARAM, and not the FIFO.
Assuming you want just that, I think you need to use 32 bit element
size. The registers can be read or written in 32 bit mode only. So use
OMAP_DMA_DATA_TYPE_S32, instead of OMAP_DMA_DATA_TYPE_S8.
Again, if you use CONSTANT addressing mode for destination, the
destination address will not be auto-incremented. Hence the only
outcome of this transfer would be that the last 4 bytes of "data"
would reside in RFBI_PARAM register, if you get to that.
>
> /*
> * DMA call back function
> */
> static void hx8340_dma_cb(int lch, u16 ch_status, void *data)
> {
> if (ch_status & OMAP2_DMA_MISALIGNED_ERR_IRQ)
> dev_dbg(hx8340.fbdev->dev, "Misaligned access\n");
> if (hx8340.dma_ch < 0)
> return;
> omap_free_dma(hx8340.dma_ch);
> hx8340.dma_ch = -1;
> }
>
> /* data is physical address of buffer */
> static int transfer_dma(u32 data, int size)
> {
> int ret = 0;
> int i;
> if (hx8340.dma_ch != -1) {
> set_current_state(TASK_UNINTERRUPTIBLE);
> schedule_timeout(100);
> omap_free_dma(hx8340.dma_ch);
> return ret;
> }
> ret = omap_request_dma(OMAP34XX_DSS_DMA3, "HX8340",
> hx8340_dma_cb, NULL, &hx8340.dma_ch);
> if (ret != 0) {
> printk("HX8340: dma request failure\n");
> return ret;
> }
> configure_dma(hx8340.dma_ch, data, size);
> return 0;
> }
> But all I get is
> DMA transaction error with device 75
>
> Is what I try to achieve at all possible? At RFBI part of CPU
> datasheet it is mentioned it is possible using sDMA
> to write these registers. So, is there some examples? I tried to use
> drivers/mmc/host/omap_hsmmc.c as example,
> but that seems to be not enough. Any ideas?
>
> S.
Do you want examples for configuring DMA in general, or configuring
RFBI ? There are many modules in drivers which use DMA ( USB, McBSP,
etc).
Venkat
--
To unsubscribe from this list: send the line "unsubscribe linux-omap" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
