From 2b52cfb1ffb282bf74098edb72c24942c0a6986b Mon Sep 17 00:00:00 2001
From: Hans de Goede <hdegoede@redhat.com>
Date: Fri, 24 Feb 2017 10:29:07 +0100
Subject: [PATCH 07/14] i2c: designware-baytrail: Fix race when resetting the
 semaphore
References: bsc#1011913
Patch-mainline: 4.12-rc1
Git-commit: 519e23a7f51e853dbe5dc4abb193c0c0db303b3a

Use iosf_mbi_modify instead of iosf_mbi_read + iosf_mbi_write so that
we keep the iosf_mbi_lock locked during the read-modify-write done to
reset the semaphore.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Acked-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/i2c/busses/i2c-designware-baytrail.c |   13 ++-----------
 1 file changed, 2 insertions(+), 11 deletions(-)

--- a/drivers/i2c/busses/i2c-designware-baytrail.c
+++ b/drivers/i2c/busses/i2c-designware-baytrail.c
@@ -57,17 +57,8 @@ static int get_sem(struct dw_i2c_dev *de
 
 static void reset_semaphore(struct dw_i2c_dev *dev)
 {
-	u32 data;
-
-	if (iosf_mbi_read(BT_MBI_UNIT_PMC, BT_MBI_BUNIT_READ,
-				PUNIT_SEMAPHORE, &data)) {
-		dev_err(dev->dev, "iosf failed to reset punit semaphore during read\n");
-		return;
-	}
-
-	data &= ~PUNIT_SEMAPHORE_BIT;
-	if (iosf_mbi_write(BT_MBI_UNIT_PMC, BT_MBI_BUNIT_WRITE,
-				PUNIT_SEMAPHORE, data))
+	if (iosf_mbi_modify(BT_MBI_UNIT_PMC, BT_MBI_BUNIT_READ, PUNIT_SEMAPHORE,
+			    0, PUNIT_SEMAPHORE_BIT))
 		dev_err(dev->dev, "iosf failed to reset punit semaphore during write\n");

 	pm_qos_update_request(&dev->pm_qos, PM_QOS_DEFAULT_VALUE);
