linux-kernel - [PATCH v2] net: samsung: sxgbe: Replace mdelay with usleep_range in sxgbe_sw

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Message-Id: <1523461910-6294-1-git-send-email-baijiaju1990@gmail.com>
Date:   Wed, 11 Apr 2018 23:51:50 +0800
From:   Jia-Ju Bai <baijiaju1990@...il.com>
To:     bh74.an@...sung.com, ks.giri@...sung.com, vipul.pandya@...sung.com
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jia-Ju Bai <baijiaju1990@...il.com>
Subject: [PATCH v2] net: samsung: sxgbe: Replace mdelay with usleep_range in sxgbe_sw_reset

sxgbe_sw_reset() is never called in atomic context.

sxgbe_sw_reset() is only called by sxgbe_drv_probe(), which is 
only called by sxgbe_platform_probe().
sxgbe_platform_probe() is set as ".probe" in struct platform_driver.
This function is not called in atomic context.

Despite never getting called from atomic context, sxgbe_sw_reset()
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>
---
v2:
* Use usleep_range() to correct usleep() in v1.

---	
 drivers/net/ethernet/samsung/sxgbe/sxgbe_main.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/samsung/sxgbe/sxgbe_main.c b/drivers/net/ethernet/samsung/sxgbe/sxgbe_main.c
index 89831ad..99cd586 100644
--- a/drivers/net/ethernet/samsung/sxgbe/sxgbe_main.c
+++ b/drivers/net/ethernet/samsung/sxgbe/sxgbe_main.c
@@ -2038,7 +2038,7 @@ static int sxgbe_sw_reset(void __iomem *addr)
 		if (!(readl(addr + SXGBE_DMA_MODE_REG) &
 		      SXGBE_DMA_SOFT_RESET))
 			break;
-		mdelay(10);
+		usleep_range(10000, 11000);
 	}

 	if (retry_count < 0)
-- 
1.9.1