Kirkwood DMA engine transfer to PCI memory space?

[Wolfgang Wegner]

Hi Saeed,

On Wed, Oct 06, 2010 at 06:27:14PM +0200, saeed bishara wrote:
> The XOR DMA engine has "address decoding windows"  that determines
> where to route transactions issued by the xor. the kernel configs only
> dram windows, you need to open windows for PCI. this ad-hoc code (not
> tested) my help:
> 
> --- a/drivers/dma/mv_xor.c
> +++ b/drivers/dma/mv_xor.c
> @@ -1274,6 +1274,15 @@ mv_xor_conf_mbus_windows(struct
> mv_xor_shared_private *msp,
>                 win_enable |= (1 << i);
>                 win_enable |= 3 << (16 + (2 * i));
>         }
> +       /* set window 4 for pcie 0 */
> +       i = 4;
> +        writel((KIRKWOOD_PCIE_MEM_PHYS_BASE & 0xffff0000) |
> +              (ATTR_PCIE_MEM << 8) |
> +               TARGET_PCIE, base + WINDOW_BASE(i));
> +        writel((KIRKWOOD_PCIE_MEM_SIZE - 1) & 0xffff0000, base +
> WINDOW_SIZE(i));
> +
> +       win_enable |= (1 << i);
> +        win_enable |= 3 << (16 + (2 * i));

thank you for this code!
It looks more sane than my dirty hack, so when we have our FPGA
burst problems solved, this could be the solution.

Somehow I did not see the window setting at first glance, and
the address error was silently ignored in the code, so it took
me some printk's to figure out what was going wrong.

Now I have to figure out how to make use of DMA to speed up
our framebuffer...

Best regards,
Wolfgang