Earlier in i2c-algo-bit driver there was no bus recovery logic
which will help to unlock the i2c bus hangs due to non-responsive
slave.
In this patch we are adding recover_bus() logic to handle bus
lockups by toggling SCL 9 times and send stop bit. This helps
release a stuck slave device by forcing it to reset and ensures
proper bus recovery after an arbitration loss.
Signed-off-by: Anindya Sundar Gayen <anindya.sg@xxxxxxxxxxx>
---
drivers/i2c/algos/i2c-algo-bit.c | 34 ++++++++++++++++++++++++++++++--
1 file changed, 32 insertions(+), 2 deletions(-)
diff --git a/drivers/i2c/algos/i2c-algo-bit.c b/drivers/i2c/algos/i2c-algo-bit.c
index eddf25b90ca8..4f74737e070b 100644
--- a/drivers/i2c/algos/i2c-algo-bit.c
+++ b/drivers/i2c/algos/i2c-algo-bit.c
@@ -29,7 +29,7 @@
#define bit_dbg(level, dev, format, args...) \
do {} while (0)
#endif /* DEBUG */
-
+#define RETRY_PULSE_CNT 9
/* ----- global variables --------------------------------------------- */
static int bit_test; /* see if the line-setting functions work */
@@ -223,6 +223,27 @@ static int i2c_inb(struct i2c_adapter *i2c_adap)
return indata;
}
+static void recover_bus(struct i2c_algo_bit_data *adap)
+{
+ int i;
+
+ pr_warn("Attempting I2C bus recovery...\n");
+
+ /* Toggle SCL 9 times to attempt recovery */
+ for (i = 0; i < RETRY_PULSE_CNT; i++) {
+ sclhi(adap);
+ udelay(adap->udelay);
+ scllo(adap);
+ udelay(adap->udelay);
+ }
+
+ /* Generate a STOP condition */
+ i2c_stop(adap);
+ udelay(adap->udelay);
+
+ pr_warn("I2C bus recovery completed.\n");
+}
+
/*
* Sanity check for the adapter hardware - check the reaction of
* the bus lines only if it seems to be idle.
@@ -248,7 +269,16 @@ static int test_bus(struct i2c_adapter *i2c_adap)
scl = adap->getscl ? getscl(adap) : 1;
if (!scl || !sda) {
pr_warn("%s: bus seems to be busy (scl=%d, sda=%d)\n", name, scl, sda);
- goto bailout;
+ recover_bus(adap);
+
+ /* Recheck bus status after recovery attempt */
+ sda = adap->getsda ? getsda(adap) : 1;
+ scl = adap->getscl ? getscl(adap) : 1;
+
+ if (!scl || !sda) {
+ pr_err("%s: bus recovery failed (scl=%d, sda=%d)\n", name, scl, sda);
+ goto bailout;
+ }
}
sdalo(adap);
--
2.17.1
