From 02096a0cf150fc8dc1cfe39afcd768d06b70e722 Mon Sep 17 00:00:00 2001
From: Arnd Bergmann <arnd@arndb.de>
Date: Wed, 13 Mar 2024 09:46:52 +0100
Subject: [PATCH] mtd: ubi: avoid expensive do_div() on 32-bit machines
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: b8a77b9a5f9c ("mtd: ubi: fix NVMEM over UBI volumes on 32-bit systems")
Fixes: 3ce485803da1 ("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>
---
drivers/mtd/ubi/nvmem.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/mtd/ubi/nvmem.c b/drivers/mtd/ubi/nvmem.c
index 8aeb9c428e510..a94a1a9aaec10 100644
--- a/drivers/mtd/ubi/nvmem.c
+++ b/drivers/mtd/ubi/nvmem.c
@@ -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;
--
GitLab