4.17-stable review patch. If anyone has any objections, please let me know.
------------------ From: Wolfram Sang <[email protected]> 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 <[email protected]> Reviewed-by: Peter Rosin <[email protected]> Signed-off-by: Wolfram Sang <[email protected]> Cc: [email protected] Signed-off-by: Greg Kroah-Hartman <[email protected]> --- 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 */
