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authorWolfram Sang <wsa+renesas@sang-engineering.com>2018-07-10 23:42:15 +0200
committerWolfram Sang <wsa@the-dreams.de>2018-07-12 23:38:18 +0200
commitabe41184abac487264a4904bfcff2d5500dccce6 (patch)
tree079664694459227f87514f271b64267315e46e3b /drivers
parent54836e2d03e76d80aec3399368ffaf5b7caadd1b (diff)
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
Diffstat (limited to 'drivers')
-rw-r--r--drivers/i2c/i2c-core-base.c11
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 */