Messages in this thread | | | Date | Wed, 12 Apr 2023 13:50:56 +0200 | From | Federico Vaga <> | Subject | Re: [PATCH] i2c: ocores: generate stop condition after timeout in polling mode |
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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@tq-group.com> >> >> 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@tq-group.com> >> Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com> > > >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; > >-- >TQ-Systems GmbH | Mühlstraße 2, Gut Delling | 82229 Seefeld, Germany >Amtsgericht München, HRB 105018 >Geschäftsführer: Detlef Schneider, Rüdiger Stahl, Stefan Schneider >http://www.tq-group.com/ >
-- Federico Vaga - CERN BE-CEM-EDL
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