Re: [PATCH 19/23] memory: omap-gpmc: Enclose macro statements in do-while

[Arnd Bergmann <arnd@arndb.de>]

On Thu, Jul 23, 2020 at 9:39 AM Krzysztof Kozlowski <krzk@kernel.org> wrote:
>
> do-while is a preferred way for complex macros because of safety
> reasons.  This fixes checkpatch error:
>
>     ERROR: Macros starting with if should be enclosed by a do - while
>         loop to avoid possible if/else logic defects
>
> Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>

This is an improvement, but the macro still has other issues that
are just as bad as the one you address:

- Using the # operator to avoid the "" in the invocation seems confusing
- it implicitly uses the 'cs' and 't' variables of the calling function instead
  of passing them as arguments.
- it calls 'return -1' in a function that otherwise uses errno-style
  return codes, so this gets interpreted as EPERM "Operation not
  permitted".

I would probably just open-code the entire thing and remove the
macro like:

ret = 0;
ret |= set_gpmc_timing_reg(cs, GPMC_CS_CONFIG2,  0,  3, 0, t->cs_on,
GPMC_CD_FCLK, "cs_on");
ret |= set_gpmc_timing_reg(cs, GPMC_CS_CONFIG2,  8,  12, 0,
t->cs_rd_off, GPMC_CD_FCLK, "cs_rd_off");
ret |= set_gpmc_timing_reg(cs, GPMC_CS_CONFIG2,  16,  20, 0,
t->cs_wr_off, GPMC_CD_FCLK, "cs_wr_off);
...
if (ret)
     return -ENXIO;

Of maybe leave the macro, but remove the if/return part and use
the "ret |= GPMC_SET_ONE(...)" trick to avoid some of the problems.

      Arnd