diff options
| author |   Wolfram Sang <wsa+renesas@sang-engineering.com> | 2018-07-10 23:42:15 +0200 |
|---|---|---|
| committer |   Wolfram Sang <wsa@the-dreams.de> | 2018-07-12 23:38:18 +0200 |
| commit | abe41184abac487264a4904bfcff2d5500dccce6 (patch) | |
| tree | 079664694459227f87514f271b64267315e46e3b | |
| parent | i2c: tegra: Fix NACK error handling (diff) | |
| download | linux-dev-abe41184abac487264a4904bfcff2d5500dccce6.tar.xz linux-dev-abe41184abac487264a4904bfcff2d5500dccce6.zip | |
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
| -rw-r--r-- | drivers/i2c/i2c-core-base.c | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c index 31d16ada6e7d..301285c54603 100644 --- 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_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 */ |