[U-Boot] [PATCH 2/3] net: davinci_emac: Round up top buffer boundaries for dcache ops

[Tom Rini]

On Sun, Aug 14, 2016 at 07:43:56PM +0000, Karl Beldan wrote:
> On Sun, Aug 14, 2016 at 11:47:25AM -0400, Tom Rini wrote:
> > On Sun, Aug 14, 2016 at 03:03:16PM +0000, Karl Beldan wrote:
> > 
> > > check_cache_range() warns that the top boundaries are not properly
> > > aligned while flushing and invalidating the buffers and make these
> > > operations to fail.
> > > ATM the RX bottom boundaries are aligned by design with EMAC_RXBUF_SIZE,
> > > properly aligned with ARCH_DMA_MINALIGN, however the top ones are not.
> > > 
> > > This gets rid of the warnings:
> > > CACHE: Misaligned operation at range
> > > 
> > > Signed-off-by: Karl Beldan <karl.beldan+oss at gmail.com>
> > > ---
> > >  drivers/net/davinci_emac.c | 6 ++++--
> > >  1 file changed, 4 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/drivers/net/davinci_emac.c b/drivers/net/davinci_emac.c
> > > index 947bfab..55461b0 100644
> > > --- a/drivers/net/davinci_emac.c
> > > +++ b/drivers/net/davinci_emac.c
> > > @@ -632,7 +632,8 @@ static int davinci_eth_send_packet (struct eth_device *dev,
> > >  				      EMAC_CPPI_EOP_BIT);
> > >  
> > >  	flush_dcache_range((unsigned long)packet,
> > > -			(unsigned long)packet + length);
> > > +			   round_up((unsigned long)packet + length,
> > > +				    ARCH_DMA_MINALIGN));
> > 
> > It's preferred to use:
> >                         (unsigned long)packet + ALIGN(length, PKTALIGN)); 
> > here instead of ARCH_DMA_MINALIGN.
> > 
> 
> Hmm, I think your suggestion is buggy.
> The cache primitives act on [laddr, haddr[, i.e. haddr is excluded, IOW
> you are missing the tail of the packet (that's why I rounded up).

Joe, we've got some instances using ALIGN(length, PKTALIGN) and others
using roundup.  And I can't imagine that we shouldn't be using the same
thing everywhere here.  So, what do you say to Karl's comment?  Thanks!

> Conceptually I still prefer ARCH_DMA_MINALIGN, also all other code in
> the base does so.

Being network code, we should use PKTALIGN here and elsewhere.

-- 
Tom
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