Re: Coding style details (checkpatch)

From	Joe Perches <joe@perches.com>
Newsgroups	linux.kernel
Subject	Re: Coding style details (checkpatch)
Date	2015-06-22 08:50 +0200
Message-ID	<pE3Im-4mu-15@gated-at.bofh.it> (permalink)
References	(4 earlier) <pD2bE-59i-17@gated-at.bofh.it> <pD5VU-26b-9@gated-at.bofh.it> <pE2CC-2QP-7@gated-at.bofh.it> <pE3fj-3OG-5@gated-at.bofh.it> <pE3yF-4bg-11@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

On Mon, 2015-06-22 at 08:38 +0200, Krzysztof Hałasa wrote:
> Joe Perches <joe@perches.com> writes:
> 
> > It might be better to use some base + index macro
> > as it could be smaller object code.
> >
> > Something like:
> >
> > #define REG_NO(base, multiplier, index)	(base + (multiplier * index))
> >
> > 	reg_write(vc->dev, REG_NO(0x10, 1, vc->ch), dma_cfg);
> > or
> >
> > #define VDMA_CHANNEL_CONFIG	0x10
> >
> > 	reg_write(vc->dev, REG_NO(VDMA_CHANNEL_CONFIG, 1, vc->ch), dma_cfg);
> 
> Wouldn't work, the register map is a bit messy.
> E.g.
> 
> #define DMA_PAGE_TABLE0_ADDR    ((const u16[8]){0x08, 0xD0, 0xD2, 0xD4, 0xD6, 0xD8, 0xDA, 0xDC})
> #define DMA_PAGE_TABLE1_ADDR    ((const u16[8]){0x09, 0xD1, 0xD3, 0xD5, 0xD7, 0xD9, 0xDB, 0xDD})

Erk, yes, a bit messy.

You could elide the 8 and checkpatch wouldn't emit a warning.

#define VDREG8(a0) ((const u16[]){			\
	a0 + 0x000, a0 + 0x010, a0 +0x020, a0 + 0x030,	\
	a0 + 0x100, a0 + 0x110, a0 +0x120, a0 + 0x130})

as "const u16[]" is a $Type but "const u16[<digits>]" is not.

Still, as written, the code seems fragile as MACRO[index]
allows index to be any value, maybe larger than the array.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
Please read the FAQ at  http://www.tux.org/lkml/

Back to linux.kernel | Previous | Next — Previous in thread | Find similar | Unroll thread

Thread

Coding style details khalasa@piap.pl (Krzysztof Hałasa) - 2015-06-19 10:40 +0200
  Re: Coding style details Frans Klaver <fransklaver@gmail.com> - 2015-06-19 11:10 +0200
    Re: Coding style details (checkpatch) khalasa@piap.pl (Krzysztof Hałasa) - 2015-06-22 07:40 +0200
      Re: Coding style details (checkpatch) Joe Perches <joe@perches.com> - 2015-06-22 08:20 +0200
        Re: Coding style details (checkpatch) khalasa@piap.pl (Krzysztof Hałasa) - 2015-06-22 08:40 +0200
          Re: Coding style details (checkpatch) Joe Perches <joe@perches.com> - 2015-06-22 08:50 +0200

csiph-web