linux-kernel - [PATCH 1/2] usb: isp1760: Replace mdelay with msleep in isp1760_init

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Date:   Tue, 10 Apr 2018 15:36:40 +0800
From:   Jia-Ju Bai <baijiaju1990@...il.com>
To:     gregkh@...uxfoundation.org
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jia-Ju Bai <baijiaju1990@...il.com>
Subject: [PATCH 1/2] usb: isp1760: Replace mdelay with msleep in isp1760_init_core

isp1760_init_core() is never called in atomic context.

The call chains ending up at isp1760_init_core() are:
[1] isp1760_init_core() <- isp1760_register() <- isp1760_plat_probe()
[2] isp1760_init_core() <- isp1760_register() <- isp1761_pci_probe()

isp1760_plat_probe() is set as ".probe" in struct platform_driver.
isp1761_pci_probe() is set as ".probe" in struct pci_driver.
These functions are not called in atomic context.

Despite never getting called from atomic context, isp1761_pci_probe()
calls mdelay() to busily wait.
This is not necessary and can be replaced with msleep() 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/usb/isp1760/isp1760-core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usb/isp1760/isp1760-core.c b/drivers/usb/isp1760/isp1760-core.c
index bfa402c..259c3eb 100644
--- a/drivers/usb/isp1760/isp1760-core.c
+++ b/drivers/usb/isp1760/isp1760-core.c
@@ -34,7 +34,7 @@ static void isp1760_init_core(struct isp1760_device *isp)
 	/* Low-level chip reset */
 	if (isp->rst_gpio) {
 		gpiod_set_value_cansleep(isp->rst_gpio, 1);
-		mdelay(50);
+		msleep(50);
 		gpiod_set_value_cansleep(isp->rst_gpio, 0);
 	}

-- 
1.9.1