diff options
| author | Du, Wenkai <wenkai.du@intel.com> | 2014-04-10 23:03:19 +0000 |
|---|---|---|
| committer | Wolfram Sang <wsa@the-dreams.de> | 2014-05-14 18:14:20 +0200 |
| commit | 47bb27e78867997040a228328f2a631c3c7f2c82 (patch) | |
| tree | 390eed0db4fe3631aeacdbef5cf388f9d73c3693 /drivers/i2c | |
| parent | d6d211db37e75de2ddc3a4f979038c40df7cc79c (diff) | |
| download | lwn-47bb27e78867997040a228328f2a631c3c7f2c82.tar.gz lwn-47bb27e78867997040a228328f2a631c3c7f2c82.zip | |
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 <wenkai.du@intel.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
[wsa: improved the comment and removed typo in commit msg]
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Cc: stable@kernel.org
Diffstat (limited to 'drivers/i2c')
| -rw-r--r-- | drivers/i2c/busses/i2c-designware-core.c | 3 |
1 files changed, 3 insertions, 0 deletions
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); |