Commit abe41184 authored Jul 10, 2018 by Wolfram Sang Committed by Wolfram Sang Jul 12, 2018

i2c: recovery: if possible send STOP with recovery pulses



I2C clients may misunderstand recovery pulses if they can't read SDA to
bail out early. In the worst case, as a write operation. To avoid that
and if we can write SDA, try to send STOP to avoid the
misinterpretation.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Peter Rosin <peda@axentia.se>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Cc: stable@kernel.org

parent 54836e2d

drivers/i2c/i2c-core-base.c

+10 −1

Original line number	Diff line number	Diff line
		@@ -198,7 +198,16 @@ int i2c_generic_scl_recovery(struct i2c_adapter *adap)

		val = !val;
		bri->set_scl(adap, val);
		ndelay(RECOVERY_NDELAY);

		/*
		* If we can set SDA, we will always create STOP here to ensure
		* the additional pulses will do no harm. This is achieved by
		* letting SDA follow SCL half a cycle later.
		*/
		ndelay(RECOVERY_NDELAY / 2);
		if (bri->set_sda)
		bri->set_sda(adap, val);
		ndelay(RECOVERY_NDELAY / 2);
		}

		/* check if recovery actually succeeded */

Admin message