[U-Boot] [PATCH V3] net: fec_mxc: allow use with cache enabled

[Mike Frysinger]

On Tuesday 13 March 2012 14:42:29 Eric Nelson wrote:
> On 03/13/2012 07:41 AM, Mike Frysinger wrote:
> > On Tuesday 13 March 2012 10:04:31 Eric Nelson wrote:
> >> --- a/drivers/net/fec_mxc.c
> >> +++ b/drivers/net/fec_mxc.c
> >> 
> >> +#if ARCH_DMA_MINALIGN>  CONFIG_SYS_CACHELINE_SIZE
> >> +#define CONFIG_FEC_ALIGN ARCH_DMA_MINALIGN
> >> +#else
> >> +#define CONFIG_FEC_ALIGN CONFIG_SYS_CACHELINE_SIZE
> >> +#endif
> > 
> > i don't think this is something you should be checking.  if this is an
> > actual problem (and i don't think it is), it's something we should
> > handle in common code.  if you need to dma from memory, then use
> > ARCH_DMA_MINALIGN.
> 
> Marek, you've mentioned some restrictions for other i.MX devices.
> 
> Are you aware of any problem collapsing this?
> 
> Note that other CPUs will need to have CONFIG_SYS_CACHELINE_SIZE to
> prevent the default of 64.

and those cores should be making sure that ARCH_DMA_MINALIGN is sufficient to 
handle those larger cache lines.  this define provides two meanings: minimum 
alignment for the DMA itself, and for sanely flushing the cache on that dma 
buffer.  so there should be no situation where ARCH_DMA_MINALIGN is smaller 
than the cacheline size.

the few boards i see defining CONFIG_SYS_CACHELINE_SIZE to 64 are all ARM 
based, and ARM sets ARCH_DMA_MINALIGN to CONFIG_SYS_CACHELINE_SIZE if it's 
defined
-mike
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