[PATCH 4.9 02/56] i2c: designware: must wait for enable

Greg Kroah-Hartman
2018-03-02T08:50:48Z

From: Ben Gardner <gardner.ben@gmail.com>

commit fba4adbbf670577e605f9ad306629db6031cd48b upstream.

One I2C bus on my Atom E3845 board has been broken since 4.9.
It has two devices, both declared by ACPI and with built-in drivers.

There are two back-to-back transactions originating from the kernel, one
targeting each device. The first transaction works, the second one locks
up the I2C controller. The controller never recovers.

These kernel logs show up whenever an I2C transaction is attempted after
this failure.
i2c-designware-pci 0000:00:18.3: timeout in disabling adapter
i2c-designware-pci 0000:00:18.3: timeout waiting for bus ready

Waiting for the I2C controller status to indicate that it is enabled
before programming it fixes the issue.

I have tested this patch on 4.14 and 4.15.

Fixes: commit 2702ea7dbec5 ("i2c: designware: wait for disable/enable only if necessary")
Cc: linux-stable <stable@vger.kernel.org> #4.13+
Signed-off-by: Ben Gardner <gardner.ben@gmail.com>
Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Ben Gardner <gardner.ben@gmail.com>
[Jarkko: Backported to v4.9..v4.12 before i2c-designware-core.c was renamed to i2c-designware-master.c]
Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/i2c/busses/i2c-designware-core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/i2c/busses/i2c-designware-core.c
+++ b/drivers/i2c/busses/i2c-designware-core.c
@@ -507,7 +507,7 @@ static void i2c_dw_xfer_init(struct dw_i
i2c_dw_disable_int(dev);

/* Enable the adapter */
- __i2c_dw_enable(dev, true);
+ __i2c_dw_enable_and_wait(dev, true);

/* Clear and enable interrupts */
dw_readl(dev, DW_IC_CLR_INTR);