On Saturday, October 10, 2015 at 09:38:46 AM, Thomas Chou wrote:
Hi Marek,
On 10/09/2015 08:57 PM, Marek Vasut wrote:
On Friday, October 09, 2015 at 05:32:47 AM, Thomas Chou wrote:
As the icache and dcache of nios2 are always enabled, the cmd_cache is no of use and the cache status, enable and disable functions can be removed.
This is no good, I want to be able to enable/disable caches to look for DMA-related issues. That is, if I disable cache, the suspicious driver works and if I enable cache, the driver does not work, I can conclude that it's a DMA/cache-related issue.
I understand. But the hardware always enables the cache if it is configured in nios2 cpu.
We can bypass (partially disable) the cache using ioremap() or dma_alloc_coherent(). If the DMA buffer address is mangled with ioremap(), then it is uncached. You may use this to debug.
OK, now it's clearer to me what you mean, thanks.
Best regards, Marek Vasut