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mtd: ubi: avoid expensive do_div() on 32-bit machines

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The use of do_div() in ubi_nvmem_reg_read() makes calling it on
32-bit machines rather expensive. Since the 'from' variable is
known to be a 32-bit quantity, it is clearly never needed and
can be optimized into a regular division operation.

Fixes: b8a77b9a5f ("mtd: ubi: fix NVMEM over UBI volumes on 32-bit systems")
Fixes: 3ce485803d ("mtd: ubi: provide NVMEM layer over UBI volumes")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Zhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
This commit is contained in:
Arnd Bergmann 2024-03-13 09:46:52 +01:00 committed by Richard Weinberger
parent 299af26eb4
commit 02096a0cf1
1 changed files with 3 additions and 3 deletions
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6
drivers/mtd/ubi/nvmem.c
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@ -6,7 +6,6 @@
/* UBI NVMEM provider */
#include "ubi.h"
#include <linux/nvmem-provider.h>
#include <asm/div64.h>
/* List of all NVMEM devices */
static LIST_HEAD(nvmem_devices);
@ -27,14 +26,15 @@ static int ubi_nvmem_reg_read(void *priv, unsigned int from,
struct ubi_nvmem *unv = priv;
struct ubi_volume_desc *desc;
uint32_t offs;
uint64_t lnum = from;
uint32_t lnum;
int err = 0;
desc = ubi_open_volume(unv->ubi_num, unv->vol_id, UBI_READONLY);
if (IS_ERR(desc))
return PTR_ERR(desc);
offs = do_div(lnum, unv->usable_leb_size);
offs = from % unv->usable_leb_size;
lnum = from / unv->usable_leb_size;
while (bytes_left) {
to_read = unv->usable_leb_size - offs;