From: Arnd Bergmann <arnd@arndb.de>
To: Lee Jones <lee.jones@linaro.org>
Subject: Re: [PATCH 08/32] dmaengine: ste_dma40: Optimise local MAX() macro
Date: Thu, 18 Apr 2013 12:46:03 +0200
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Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        linus.walleij@stericsson.com, Vinod Koul <vinod.koul@intel.com>,
        Dan Williams <djbw@fb.com>, Per Forlin <per.forlin@stericsson.com>,
        Rabin Vincent <rabin@rab.in>
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On Thursday 18 April 2013, Lee Jones 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.

No, it does not.

> index b21a8a3..7b451b2 100644
> --- a/drivers/dma/ste_dma40.c
> +++ b/drivers/dma/ste_dma40.c
> @@ -53,7 +53,7 @@
>  #define D40_ALLOC_PHY          BIT(30)
>  #define D40_ALLOC_LOG_FREE     BIT(0)
>  
> -#define MAX(a, b) (((a) < (b)) ? (b) : (a))
> +#define MAX(a, b) ((a > b) ? a : b)

This just makes the macro worse in case you pass a complex expression
in, which can now have additional unwanted effects. Just drop this patch.

	Arnd
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