| From 47bb27e78867997040a228328f2a631c3c7f2c82 Mon Sep 17 00:00:00 2001 |
| From: "Du, Wenkai" <wenkai.du@intel.com> |
| Date: Thu, 10 Apr 2014 23:03:19 +0000 |
| Subject: i2c: designware: Mask all interrupts during i2c controller enable |
| |
| From: "Du, Wenkai" <wenkai.du@intel.com> |
| |
| 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@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> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| drivers/i2c/busses/i2c-designware-core.c | 3 +++ |
| 1 file changed, 3 insertions(+) |
| |
| --- a/drivers/i2c/busses/i2c-designware-core.c |
| +++ b/drivers/i2c/busses/i2c-designware-core.c |
| @@ -380,6 +380,9 @@ static void i2c_dw_xfer_init(struct dw_i |
| ic_con &= ~DW_IC_CON_10BITADDR_MASTER; |
| dw_writel(dev, ic_con, DW_IC_CON); |
| |
| + /* enforce disabled interrupts (due to HW issues) */ |
| + i2c_dw_disable_int(dev); |
| + |
| /* Enable the adapter */ |
| __i2c_dw_enable(dev, true); |
| |
