Re: Coding style details (checkpatch)

Joe Perches
2015-06-22T06:48:01Z

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.