[PATCH v3 07/12] i2c: designware-baytrail: Fix race when resetting the semaphore

Hans de Goede
2017-02-10T10:27:57Z

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>
---
Changes in v5:
-New patch in v5 of this patch-set
---
drivers/i2c/busses/i2c-designware-baytrail.c | 11 ++---------
1 file changed, 2 insertions(+), 9 deletions(-)

diff --git a/drivers/i2c/busses/i2c-designware-baytrail.c b/drivers/i2c/busses/i2c-designware-baytrail.c
index 650a700..8df529c 100644
--- a/drivers/i2c/busses/i2c-designware-baytrail.c
+++ b/drivers/i2c/busses/i2c-designware-baytrail.c
@@ -47,15 +47,8 @@ static int get_sem(struct dw_i2c_dev *dev, u32 *sem)

static void reset_semaphore(struct dw_i2c_dev *dev)
{
- u32 data;
-
- if (iosf_mbi_read(BT_MBI_UNIT_PMC, MBI_REG_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, MBI_REG_WRITE, PUNIT_SEMAPHORE, data))
+ if (iosf_mbi_modify(BT_MBI_UNIT_PMC, MBI_REG_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);
--
2.9.3

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