This is a note to let you know that I've just added the patch titled
i2c: designware: always clear interrupts before enabling them
to the 3.4-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-always-clear-interrupts-before-enabling-them.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 2a2d95e9d6d29e726cc294b65391917ed2e32bf4 Mon Sep 17 00:00:00 2001
From: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
Date: Mon, 13 May 2013 00:54:30 +0000
Subject: i2c: designware: always clear interrupts before enabling them
From: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
commit 2a2d95e9d6d29e726cc294b65391917ed2e32bf4 upstream.
If the I2C bus is put to a low power state by an ACPI method it might pull
the SDA line low (as its power is removed). Once the bus is put to full
power state again, the SDA line is pulled back to high. This transition
looks like a STOP condition from the controller point-of-view which sets
STOP detected bit in its status register causing the driver to fail
subsequent transfers.
Fix this by always clearing all interrupts before we start a transfer.
Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
Signed-off-by: Wolfram Sang <wsa@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/i2c/busses/i2c-designware-core.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/drivers/i2c/busses/i2c-designware-core.c
+++ b/drivers/i2c/busses/i2c-designware-core.c
@@ -349,7 +349,8 @@ static void i2c_dw_xfer_init(struct dw_i
/* Enable the adapter */
dw_writel(dev, 1, DW_IC_ENABLE);
- /* Enable interrupts */
+ /* Clear and enable interrupts */
+ i2c_dw_clear_int(dev);
dw_writel(dev, DW_IC_INTR_DEFAULT_MASK, DW_IC_INTR_MASK);
}
Patches currently in stable-queue which might be from mika.westerberg@xxxxxxxxxxxxxxx are
queue-3.4/i2c-designware-always-clear-interrupts-before-enabling-them.patch
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