linux-kernel - [PATCH] [v2] media: i2c: mt9m114: use fsleep() in place of udelay()

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Date:   Wed, 13 Dec 2023 12:23:07 +0100
From:   Arnd Bergmann <arnd@...nel.org>
To:     Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Nathan Chancellor <nathan@...nel.org>,
        Jacopo Mondi <jacopo.mondi@...asonboard.com>,
        Hans Verkuil <hverkuil-cisco@...all.nl>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Bill Wendling <morbo@...gle.com>,
        Justin Stitt <justinstitt@...gle.com>,
        Tomi Valkeinen <tomi.valkeinen@...asonboard.com>,
        Shuah Khan <skhan@...uxfoundation.org>,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        llvm@...ts.linux.dev
Subject: [PATCH] [v2] media: i2c: mt9m114: use fsleep() in place of udelay()

From: Arnd Bergmann <arnd@...db.de>

With clang-16, building without COMMON_CLK triggers a range check on
udelay() because of a constant division-by-zero calculation:

ld.lld: error: undefined symbol: __bad_udelay
>>> referenced by mt9m114.c
>>>               drivers/media/i2c/mt9m114.o:(mt9m114_power_on) in archive vmlinux.a

In this configuration, the driver already fails to probe, before
this function gets called, so it's enough to suppress the assertion.

Do this by using fsleep(), which turns long delays into sleep() calls
in place of the link failure.

This is probably a good idea regardless to avoid overly long dynamic
udelay() calls on a slow clock.

Cc: Sakari Ailus <sakari.ailus@...ux.intel.com>
Fixes: 24d756e914fc ("media: i2c: Add driver for onsemi MT9M114 camera sensor")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 drivers/media/i2c/mt9m114.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/media/i2c/mt9m114.c b/drivers/media/i2c/mt9m114.c
index 0a22f328981d..68adaecaf481 100644
--- a/drivers/media/i2c/mt9m114.c
+++ b/drivers/media/i2c/mt9m114.c
@@ -2116,7 +2116,7 @@ static int mt9m114_power_on(struct mt9m114 *sensor)
 		duration = DIV_ROUND_UP(2 * 50 * 1000000, freq);
 
 		gpiod_set_value(sensor->reset, 1);
-		udelay(duration);
+		fsleep(duration);
 		gpiod_set_value(sensor->reset, 0);
 	} else {
 		/*
-- 
2.39.2