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. This patch requires https://patchwork.kernel.org/patch/2601241/ to be applied first. Signed-off-by: Christian Ruppert <christian.ruppert@xxxxxxxxxx> --- drivers/i2c/busses/i2c-designware-core.c | 10 ++++++++-- 1 files changed, 8 insertions(+), 2 deletions(-) diff --git a/drivers/i2c/busses/i2c-designware-core.c b/drivers/i2c/busses/i2c-designware-core.c index b75d292..55a9991 100644 --- a/drivers/i2c/busses/i2c-designware-core.c +++ b/drivers/i2c/busses/i2c-designware-core.c @@ -588,11 +588,19 @@ 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. + */ + __i2c_dw_enable(dev, false); + if (dev->msg_err) { ret = dev->msg_err; goto done; @@ -600,8 +608,6 @@ 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; } -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
