Re: [PATCH 2/7] usb: chipidea: add freescale imx28 special write register method

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On Fri, Jan 10, 2014 at 03:09:03PM +0000, David Laight wrote:
> > > This code ought to be defensive against 'imx28_write_fix' being
> > > set when the kernel isn't compiled with CONFIG_SOC_IMX28.
> > > This can easily be done by changing the #else block to do an iowrite().
> > 
> > You missed the long email thread we just had about this earlier in the
> > week...
> 
> No - I read most of it, I even commented earlier than the alternate
> definition of imx28_ci_writel() should be iowrite32().

That would work too.

> Getting static branch prediction right can make a significant difference.
> Although each branch is only a few clocks they can soon add up.
> Protocol stack code can easily be dominated by conditionals,
> removing pipeline stalls can easily speed things up by a measurable 10%.

If you can measure a problem with the code as-is, great, I'll be glad to
take a patch, otherwise we are just bike-shedding, and I'm sure the gcc
developers would love a bug report as to how they aren't getting the
static inline empty function logic correct :)

thanks,

greg k-h
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