From: "Du, Wenkai" <wenkai.du@xxxxxxxxx> This patch has been added to the 3.12 stable tree. If you have any objections, please let us know. =============== commit 47bb27e78867997040a228328f2a631c3c7f2c82 upstream. There have been "i2c_designware 80860F41:00: controller timed out" errors on a number of Baytrail platforms. The issue is caused by incorrect value in Interrupt Mask Register (DW_IC_INTR_MASK) when i2c core is being enabled. This causes call to __i2c_dw_enable() to immediately start the transfer which leads to timeout. There are 3 failure modes observed: 1. Failure in S0 to S3 resume path The default value after reset for DW_IC_INTR_MASK is 0x8ff. When we start the first transaction after resuming from system sleep, TX_EMPTY interrupt is already unmasked because of the hardware default. 2. Failure in normal operational path This failure happens rarely and is hard to reproduce. Debug trace showed that DW_IC_INTR_MASK had value of 0x254 when failure occurred, which meant TX_EMPTY was unmasked. 3. Failure in S3 to S0 suspend path This failure also happens rarely and is hard to reproduce. Adding debug trace that read DW_IC_INTR_MASK made this failure not reproducible. But from ISR call trace we could conclude TX_EMPTY was unmasked when problem occurred. The patch masks all interrupts before the controller is enabled to resolve the faulty DW_IC_INTR_MASK conditions. Signed-off-by: Wenkai Du <wenkai.du@xxxxxxxxx> Acked-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> [wsa: improved the comment and removed typo in commit msg] Signed-off-by: Wolfram Sang <wsa@xxxxxxxxxxxxx> Signed-off-by: Jiri Slaby <jslaby@xxxxxxx> --- drivers/i2c/busses/i2c-designware-core.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/i2c/busses/i2c-designware-core.c b/drivers/i2c/busses/i2c-designware-core.c index 5888feef1ac5..a4dd9bdf737b 100644 --- a/drivers/i2c/busses/i2c-designware-core.c +++ b/drivers/i2c/busses/i2c-designware-core.c @@ -418,6 +418,9 @@ static void i2c_dw_xfer_init(struct dw_i2c_dev *dev) */ dw_writel(dev, msgs[dev->msg_write_idx].addr | ic_tar, DW_IC_TAR); + /* enforce disabled interrupts (due to HW issues) */ + i2c_dw_disable_int(dev); + /* Enable the adapter */ __i2c_dw_enable(dev, true); -- 1.9.3 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html