From 47bb27e78867997040a228328f2a631c3c7f2c82 Mon Sep 17 00:00:00 2001 From: "Du, Wenkai" Date: Thu, 10 Apr 2014 23:03:19 +0000 Subject: i2c: designware: Mask all interrupts during i2c controller enable 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 Acked-by: Mika Westerberg [wsa: improved the comment and removed typo in commit msg] Signed-off-by: Wolfram Sang Cc: stable@kernel.org --- drivers/i2c/busses/i2c-designware-core.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'drivers/i2c/busses/i2c-designware-core.c') diff --git a/drivers/i2c/busses/i2c-designware-core.c b/drivers/i2c/busses/i2c-designware-core.c index 22e92c3d3d07..3c20e4bd6dd1 100644 --- a/drivers/i2c/busses/i2c-designware-core.c +++ b/drivers/i2c/busses/i2c-designware-core.c @@ -422,6 +422,9 @@ 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); -- cgit v1.2.3