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 # v4.9..v4.12 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 --- drivers/i2c/busses/i2c-designware-core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/i2c/busses/i2c-designware-core.c b/drivers/i2c/busses/i2c-designware-core.c index 809f4d4e93a0..340e037b3224 100644 --- 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_i2c_dev *dev) 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);