[1/2] i2c-designware: always clear interrupts before enabling them

Submitted by Mika Westerberg on May 13, 2013, 10:54 a.m.

Details

Message ID 1368442471-7582-1-git-send-email-mika.westerberg@linux.intel.com
State Accepted
Headers show

Commit Message

Mika Westerberg May 13, 2013, 10:54 a.m.
If the I2C bus is put to a low power state by an ACPI method it might pull
the SDA line low (as its power is removed). Once the bus is put to full
power state again, the SDA line is pulled back to high. This transition
looks like a STOP condition from the controller point-of-view which sets
STOP detected bit in its status register causing the driver to fail
subsequent transfers.

Fix this by always clearing all interrupts before we start a transfer.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
---
 drivers/i2c/busses/i2c-designware-core.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Comments

Wolfram Sang May 17, 2013, 8:31 a.m.
On Mon, May 13, 2013 at 01:54:30PM +0300, Mika Westerberg wrote:
> If the I2C bus is put to a low power state by an ACPI method it might pull
> the SDA line low (as its power is removed). Once the bus is put to full
> power state again, the SDA line is pulled back to high. This transition
> looks like a STOP condition from the controller point-of-view which sets
> STOP detected bit in its status register causing the driver to fail
> subsequent transfers.
> 
> Fix this by always clearing all interrupts before we start a transfer.
> 
> Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>

Applied to for-current, thanks! Added stable, too.

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diff --git a/drivers/i2c/busses/i2c-designware-core.c b/drivers/i2c/busses/i2c-designware-core.c
index 21fbb34..7a89ca5 100644
--- a/drivers/i2c/busses/i2c-designware-core.c
+++ b/drivers/i2c/busses/i2c-designware-core.c
@@ -383,7 +383,8 @@  static void i2c_dw_xfer_init(struct dw_i2c_dev *dev)
 	/* Enable the adapter */
 	__i2c_dw_enable(dev, true);
 
-	/* Enable interrupts */
+	/* Clear and enable interrupts */
+	i2c_dw_clear_int(dev);
 	dw_writel(dev, DW_IC_INTR_DEFAULT_MASK, DW_IC_INTR_MASK);
 }