4.17-stable review patch. If anyone has any objections, please let me know.
------------------
From: Wolfram Sang <wsa+rene...@sang-engineering.com>
commit abe41184abac487264a4904bfcff2d5500dccce6 upstream.
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+rene...@sang-engineering.com>
Reviewed-by: Peter Rosin <p...@axentia.se>
Signed-off-by: Wolfram Sang <w...@the-dreams.de>
Cc: sta...@kernel.org
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
drivers/i2c/i2c-core-base.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -198,7 +198,16 @@ int i2c_generic_scl_recovery(struct i2c_
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 */
