This is a note to let you know that I've just added the patch titled
i2c: designware: Mask all interrupts during i2c controller enable
to the 3.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
i2c-designware-mask-all-interrupts-during-i2c-controller-enable.patch
and it can be found in the queue-3.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 47bb27e78867997040a228328f2a631c3c7f2c82 Mon Sep 17 00:00:00 2001
From: "Du, Wenkai" <[email protected]>
Date: Thu, 10 Apr 2014 23:03:19 +0000
Subject: i2c: designware: Mask all interrupts during i2c controller enable
From: "Du, Wenkai" <[email protected]>
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 <[email protected]>
Acked-by: Mika Westerberg <[email protected]>
[wsa: improved the comment and removed typo in commit msg]
Signed-off-by: Wolfram Sang <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
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
@@ -417,6 +417,9 @@ static void i2c_dw_xfer_init(struct dw_i
*/
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);
Patches currently in stable-queue which might be from [email protected] are
queue-3.14/i2c-designware-mask-all-interrupts-during-i2c-controller-enable.patch
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