| Message ID | 20120529100646.GA23383@faui49q.informatik.uni-erlangen.de |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, 2012-05-29 at 12:06 +0200, Christian Dietrich wrote: > When CONFIG_ARCH_NETWINDER is unset nw_en_write is a NOP. But > machine_is_netwinder() also checks for > CONFIG_ARCH_NETWINDER. Therefore in the !netwinder case the > preprocessed code is: > > if (0) > do {} while(0); It's not a double check. It's a compile time check for "do we even need to build this code at all?", and a separate run time check for "do we need to run this code now?". Think about the case where CONFIG_ARCH_NETWINDER is set, but you aren't actually running this kernel binary on a netwinder *today*. Yes, we might not support multi-platform kernels on ARM yet, but we are slowly getting there. This kind of change just makes that harder. And even if the machine_is_netwinder() "function" is *currently* a macro which is hard-coded to return one or zero, that just means that your change achieves nothing in the compiler output. It'll be silently optimised away, or not, as appropriate.
diff --git a/drivers/mtd/maps/dc21285.c b/drivers/mtd/maps/dc21285.c index 86598a1..38fbf23 100644 --- a/drivers/mtd/maps/dc21285.c +++ b/drivers/mtd/maps/dc21285.c @@ -79,8 +79,7 @@ static void dc21285_copy_from(struct map_info *map, void *to, unsigned long from static void dc21285_write8(struct map_info *map, const map_word d, unsigned long adr) { - if (machine_is_netwinder()) - nw_en_write(); + nw_en_write(); *CSR_ROMWRITEREG = adr & 3; adr &= ~3; *(uint8_t*)(map->virt + adr) = d.x[0]; @@ -88,8 +87,7 @@ static void dc21285_write8(struct map_info *map, const map_word d, unsigned long static void dc21285_write16(struct map_info *map, const map_word d, unsigned long adr) { - if (machine_is_netwinder()) - nw_en_write(); + nw_en_write(); *CSR_ROMWRITEREG = adr & 3; adr &= ~3; *(uint16_t*)(map->virt + adr) = d.x[0]; @@ -97,8 +95,7 @@ static void dc21285_write16(struct map_info *map, const map_word d, unsigned lon static void dc21285_write32(struct map_info *map, const map_word d, unsigned long adr) { - if (machine_is_netwinder()) - nw_en_write(); + nw_en_write(); *(uint32_t*)(map->virt + adr) = d.x[0]; }
When CONFIG_ARCH_NETWINDER is unset nw_en_write is a NOP. But machine_is_netwinder() also checks for CONFIG_ARCH_NETWINDER. Therefore in the !netwinder case the preprocessed code is: if (0) do {} while(0); Signed-off-by: Christian Dietrich <christian.dietrich@informatik.uni-erlangen.de> --- drivers/mtd/maps/dc21285.c | 9 +++------ 1 files changed, 3 insertions(+), 6 deletions(-)