[U-Boot] [PATCH 2/4] net: round up before calling flush_cache

[Marek Vasut]

Dear Mike Frysinger,

> On Sunday 01 April 2012 17:00:56 Marek Vasut wrote:
> > Dear Mike Frysinger,
> > 
> > > On Sunday 01 April 2012 09:22:59 Stefano Babic wrote:
> > > > If the range passed to flush_cache is not multiple
> > > > of ARCH_DMA_MINALIGN, a warning due to mislaignment
> > > > is printed.
> > > > Detected with fec_mxc, mx35 boards:
> > > > 
> > > > CACHE: Misaligned operation at range [80800000, 8083c310]
> > > 
> > > warning on flushing is broken.  the arch/arm/cpu/arm926ejs/cache.c code
> > > should probably be fixed instead.
> > 
> > Why exactly?
> 
> the flush isn't harmful (ignoring the fact that a few extra bytes might get
> written back to external memory), and the data isn't evicted from cache.
> after all, we aren't talking about invalidate here, we're talking about
> flush.

Right ... and can you be sure nothing important is overwritten in RAM?

> plus, no other arch (linux or u-boot) does this.
> 
> so the better question is, why exactly should you be warning ?  you should
> provide justification when doing something unusual ...

Because you can destroy data in DRAM that arrived there by DMA transfer for 
example?

> -mike

Best regards,
Marek Vasut