summaryrefslogtreecommitdiff
path: root/drivers/i2c/busses
diff options
context:
space:
mode:
authorChristian Ruppert <christian.ruppert@abilis.com>2013-06-07 10:51:23 +0200
committerWolfram Sang <wsa@the-dreams.de>2013-06-15 13:04:32 +0200
commit38d7fadef4973bb94e36897fcb6bb6a12fdd10c9 (patch)
tree3f42a138a920735fcdfad05862636903ff13c827 /drivers/i2c/busses
parent8419c8debdc600b71fb89f0ffad80a6f436d80fe (diff)
i2c: designware: fix race between subsequent xfers
The designware block is not always properly disabled in the case of transfer errors. Interrupts from aborted transfers might be handled after the data structures for the following transfer are initialised but before the hardware is set up. This can corrupt the data structures to the point that the system is stuck in an infinite interrupt loop (where FIFOs are never emptied because dev->msg_read_idx == dev->msgs_num). This patch cleanly disables the designware-i2c hardware at the end of every transfer, be it successful or not. Signed-off-by: Christian Ruppert <christian.ruppert@abilis.com> [wsa: extended the comment] Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Diffstat (limited to 'drivers/i2c/busses')
-rw-r--r--drivers/i2c/busses/i2c-designware-core.c12
1 files changed, 10 insertions, 2 deletions
diff --git a/drivers/i2c/busses/i2c-designware-core.c b/drivers/i2c/busses/i2c-designware-core.c
index db20a2841b75..3de549436992 100644
--- a/drivers/i2c/busses/i2c-designware-core.c
+++ b/drivers/i2c/busses/i2c-designware-core.c
@@ -583,11 +583,21 @@ i2c_dw_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
ret = wait_for_completion_timeout(&dev->cmd_complete, HZ);
if (ret == 0) {
dev_err(dev->dev, "controller timed out\n");
+ /* i2c_dw_init implicitly disables the adapter */
i2c_dw_init(dev);
ret = -ETIMEDOUT;
goto done;
}
+ /*
+ * We must disable the adapter before unlocking the &dev->lock mutex
+ * below. Otherwise the hardware might continue generating interrupts
+ * which in turn causes a race condition with the following transfer.
+ * Needs some more investigation if the additional interrupts are
+ * a hardware bug or this driver doesn't handle them correctly yet.
+ */
+ __i2c_dw_enable(dev, false);
+
if (dev->msg_err) {
ret = dev->msg_err;
goto done;
@@ -595,8 +605,6 @@ i2c_dw_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
/* no error */
if (likely(!dev->cmd_err)) {
- /* Disable the adapter */
- __i2c_dw_enable(dev, false);
ret = num;
goto done;
}