[U-Boot] [PATCH] nios2: zap cache status enable and disable functions

Marek Vasut marex at denx.de
Sat Oct 10 20:10:01 CEST 2015


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


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