On Wed, Apr 12, 2023 at 11:49:32AM +0200, Matthias Schiffer wrote:
On Mon, 2023-02-20 at 16:17 +0000, Matthias Schiffer wrote:
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.
I can see and confirm the bug.
The patch seems fine to me, but I do not have the hardware at hand right now for a
real test.
Following a few cosmetic comments.
Fixes: 69c8c0c0efa8 ("i2c: ocores: add polling interface")
Signed-off-by: Gregor Herburger <gregor.herburger@xxxxxxxxxxxx>
Signed-off-by: Matthias Schiffer <matthias.schiffer@xxxxxxxxxxxxxxx>
Any chance we can get someone to have a look at this patch?
Regards,
Matthias
---
drivers/i2c/busses/i2c-ocores.c | 28 +++++++++++++++-------------
1 file changed, 15 insertions(+), 13 deletions(-)
diff --git a/drivers/i2c/busses/i2c-ocores.c b/drivers/i2c/busses/i2c-ocores.c
index a0af027db04c1..28bcda3f7040a 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;
err = ocores_poll_wait(i2c);
- if (err) {
- i2c->state = STATE_ERROR;
- break; /* timeout */
- }
+ if (err)
+ return err;
ret = ocores_isr(-1, i2c);
if (ret == IRQ_NONE)
@@ -364,6 +364,8 @@ static void ocores_process_polling(struct ocores_i2c *i2c)
break;
}
}
+
+ return 0;
}
I would try to have a single return point at the end `return err` and inside the
loop just a break.
static int ocores_xfer_core(struct ocores_i2c *i2c,
@@ -387,16 +389,16 @@ static int ocores_xfer_core(struct ocores_i2c *i2c,
oc_setreg(i2c, OCI2C_DATA, i2c_8bit_addr_from_msg(i2c->msg));
oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_START);
- if (polling) {
- ocores_process_polling(i2c);
- } else {
+ if (polling)
+ 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;
- }
+ (i2c->state == STATE_DONE), HZ) ?
+ 0 : -ETIMEDOUT;
For readability, I would avoid the ternary operator here and do the assignement
with an `if` as it was before.
if (ret == 0)
ret = -ETIMEDOUT;
+ if (ret) {
+ ocores_process_timeout(i2c);
+ return ret;
}
return (i2c->state == STATE_DONE) ? num : -EIO;
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