From: Gregor Herburger <gregor.herburger@xxxxxxxxxxxx>
In polling mode, no stop condition is generated after a timeout. This
causes SCL to remain low and thereby block the bus. If this happens
during a transfer it can cause slaves to misinterpret the subsequent
transfer and return wrong values.
To solve this, pass the ETIMEDOUT error up from ocores_process_polling()
instead of setting STATE_ERROR directly. The caller is adjusted to call
ocores_process_timeout() on error both in polling and in IRQ mode, which
will set STATE_ERROR and generate a stop condition.
Fixes: 69c8c0c0efa8 ("i2c: ocores: add polling interface")
Signed-off-by: Gregor Herburger <gregor.herburger@xxxxxxxxxxxx>
Signed-off-by: Matthias Schiffer <matthias.schiffer@xxxxxxxxxxxxxxx>
---
v2: style improvements based on feedback from Federico and Andrew. I went
with a slightly different solution than Andrew suggested to avoid using
the ret variable for two different kinds of returns.
drivers/i2c/busses/i2c-ocores.c | 35 ++++++++++++++++++---------------
1 file changed, 19 insertions(+), 16 deletions(-)
diff --git a/drivers/i2c/busses/i2c-ocores.c b/drivers/i2c/busses/i2c-ocores.c
index a0af027db04c1..2e575856c5cd5 100644
--- a/drivers/i2c/busses/i2c-ocores.c
+++ b/drivers/i2c/busses/i2c-ocores.c
@@ -342,18 +342,18 @@ static int ocores_poll_wait(struct ocores_i2c *i2c)
* ocores_isr(), we just add our polling code around it.
*
* It can run in atomic context
+ *
+ * Return: 0 on success, -ETIMEDOUT on timeout
*/
-static void ocores_process_polling(struct ocores_i2c *i2c)
+static int ocores_process_polling(struct ocores_i2c *i2c)
{
- while (1) {
- irqreturn_t ret;
- int err;
+ irqreturn_t ret;
+ int err = 0;
+ while (1) {
err = ocores_poll_wait(i2c);
- if (err) {
- i2c->state = STATE_ERROR;
+ if (err)
break; /* timeout */
- }
ret = ocores_isr(-1, i2c);
if (ret == IRQ_NONE)
@@ -364,13 +364,15 @@ static void ocores_process_polling(struct ocores_i2c *i2c)
break;
}
}
+
+ return err;
}
static int ocores_xfer_core(struct ocores_i2c *i2c,
struct i2c_msg *msgs, int num,
bool polling)
{
- int ret;
+ int ret = 0;
u8 ctrl;
ctrl = oc_getreg(i2c, OCI2C_CONTROL);
@@ -388,15 +390,16 @@ static int ocores_xfer_core(struct ocores_i2c *i2c,
oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_START);
if (polling) {
- ocores_process_polling(i2c);
+ ret = ocores_process_polling(i2c);
} else {
- ret = wait_event_timeout(i2c->wait,
- (i2c->state == STATE_ERROR) ||
- (i2c->state == STATE_DONE), HZ);
- if (ret == 0) {
- ocores_process_timeout(i2c);
- return -ETIMEDOUT;
- }
+ if (wait_event_timeout(i2c->wait,
+ (i2c->state == STATE_ERROR) ||
+ (i2c->state == STATE_DONE), HZ) == 0)
+ ret = -ETIMEDOUT;
+ }
+ if (ret) {
+ ocores_process_timeout(i2c);
+ return ret;
}
return (i2c->state == STATE_DONE) ? num : -EIO;
--
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