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Re: [PATCH] TXx9 SPI controller driver (take 2)

To: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Subject: Re: [PATCH] TXx9 SPI controller driver (take 2)
From: David Brownell <david-b@pacbell.net>
Date: Sat, 30 Jun 2007 10:46:20 -0700
Cc: linux-mips@linux-mips.org, ralf@linux-mips.org, sshtylyov@ru.mvista.com, mlachwani@mvista.com, spi-devel-general@lists.sourceforge.net
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On Saturday 30 June 2007, Atsushi Nemoto wrote:
> On Sat, 30 Jun 2007 09:53:19 -0700, David Brownell <david-b@pacbell.net> 
> wrote:
> > > This is a driver for SPI controller built into TXx9 MIPS SoCs.
> > > This driver is derived from arch/mips/tx4938/toshiba_rbtx4938/spi_txx9.c.
> > > 
> > > Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
> > > ---
> > > Changes from previous version:
> > 
> > Better, but still not there yet.
> 
> Thanks!  I'll be back with take 3 patch.
> 
> > > + txx9spi_cs_func(spi, c, 0, 1000000000 / 2 / spi->max_speed_hz);
> > 
> > You still use this confusing A/2/B syntax.  Please
> > rewrite that using one "/" and one "*".  (And there
> > is similar usage elsewhere.)
> 
> The compiler will optimize "1000000000 / 2 / spi->max_speed_hz" into
> "500000000 / spi->max_speed_hz", so it can be treat as one "/", no?

Sure it's deterministic.  But that doesn't prevent me from
needing a double-take to figure what it does ... it's best
to avoid confusing idioms in code.  At the very least, put
parentheses there ...


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