Re: [PATCH 05/32] dmaengine: ste_dma40: Supply macros to resolve'src' and 'dst' directions

[Linus Walleij]

On Thu, Apr 18, 2013 at 12:11 PM, Lee Jones <lee.jones@xxxxxxxxxx> wrote:

> There are lots of lengthy if() statements located sporadically up and
> down the driver. This simple macro should make many of them a little
> simpler to decipher. The remainder have to stay in place, as they
> detail slightly more specific settings.
>
> Cc: Vinod Koul <vinod.koul@xxxxxxxxx>
> Cc: Dan Williams <djbw@xxxxxx>
> Cc: Per Forlin <per.forlin@xxxxxxxxxxxxxx>
> Cc: Rabin Vincent <rabin@xxxxxx>
> Signed-off-by: Lee Jones <lee.jones@xxxxxxxxxx>
(...)

> +#define D40_IS_SRC(dir)  ((dir == STEDMA40_PERIPH_TO_MEM) ? true : false)

And when I reas the code and see D40_IS_SRC, what does that
mean? That the channel is a source of .. what exactly?

The older explicit comparison would be more informative.

> +#define D40_IS_DST(dir) (((dir == STEDMA40_MEM_TO_PERIPH) || \
> +                         (dir == STEDMA40_MEM_TO_MEM)) ? true : false)
> +

The comparison to STEDMA40_MEM_TO_MEM is unintelligible, if I see
that macro it has a very unintuitive name, since it is not just
DST but also SRC.

The latter macro would be named somthing like D40_IS_DST_OR_MEM2MEM
and then it will not simplify the code very much.

You need to come up with something different here, this is just making the
driver harder to understand.

I think this patch should be just dropped.

Yours,
Linus Walleij
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