linux-kernel - [PATCH] gpu: drm: bridge: adv7511: Replace mdelay with usleep_range in adv7511

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Date:   Wed, 11 Apr 2018 16:33:42 +0800
From:   Jia-Ju Bai <baijiaju1990@...il.com>
To:     architt@...eaurora.org, a.hajda@...sung.com,
        Laurent.pinchart@...asonboard.com, airlied@...ux.ie,
        daniel.vetter@...ll.ch, bhumirks@...il.com,
        narmstrong@...libre.com, inki.dae@...sung.com
Cc:     dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Jia-Ju Bai <baijiaju1990@...il.com>
Subject: [PATCH] gpu: drm: bridge: adv7511: Replace mdelay with usleep_range in adv7511_probe

adv7511_probe() is never called in atomic context.
This function is only set as ".probe" in struct i2c_driver.

Despite never getting called from atomic context, adv7511_probe()
calls mdelay() to busily wait.
This is not necessary and can be replaced with usleep_range() to
avoid busy waiting.

This is found by a static analysis tool named DCNS written by myself.
And I also manually check it.

Signed-off-by: Jia-Ju Bai <baijiaju1990@...il.com>
---
 drivers/gpu/drm/bridge/adv7511/adv7511_drv.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
index b2431ae..2cf7fa1 100644
--- a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
+++ b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
@@ -1054,7 +1054,7 @@ static int adv7511_probe(struct i2c_client *i2c, const struct i2c_device_id *id)
 	}
 
 	if (adv7511->gpio_pd) {
-		mdelay(5);
+		usleep_range(5000, 6000);
 		gpiod_set_value_cansleep(adv7511->gpio_pd, 0);
 	}
 
-- 
1.9.1