Subject: [PATCH 08/32] dmaengine: ste_dma40: Optimise local MAX() macro

From: [email-masked] (Lee Jones)
Date: Thu, 25 Apr 2013 10:15:44 +0100

On Thu, 25 Apr 2013, Linus Walleij wrote:

> On Thu, Apr 18, 2013 at 12:11 PM, Lee Jones <[email-masked]> wrote:
> 
> > The current implementation of the DMA40's local MAX() macro evaluates
> > its arguments more times than is necessary. This patch strips it
> > optimises it to only evaluate what's appropriate.
> >
> > Cc: Vinod Koul <[email-masked]>
> > Cc: Dan Williams <[email-masked]>
> > Cc: Per Forlin <[email-masked]>
> > Cc: Rabin Vincent <[email-masked]>
> > Reported-by: Harvey Harrison <[email-masked]>
> > Signed-off-by: Lee Jones <[email-masked]>
> (...)
> > -#define MAX(a, b) (((a) < (b)) ? (b) : (a))
> > +#define MAX(a, b) ((a > b) ? a : b)
> 
> Much has been said about this patch already, but notice what it is
> used for instead, one single thing at compile-time:
> 
> struct d40_base {
> (...)
>         u32
> reg_val_backup_v4[MAX(BACKUP_REGS_SZ_V4A, BACKUP_REGS_SZ_V4B)];
> (...)
> };
> 
> i.e. defining the size of that array at compile-time.
> 
> The actual size is figured out in d40_hw_detect_init().
> 
> So what about you just devm_kmalloc() that array instead and
> delete this macro. That is the real fix.

I'm happy to do it, but please see v2 of this patch first.

-- 
Lee Jones
Linaro ST-Ericsson Landing Team Lead
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