[PATCH] i2c: designware: Don't mask TX_EMPTY if write is in progress
jszhang at marvell.com
Sun Nov 1 19:33:47 PST 2015
On Fri, 30 Oct 2015 14:03:53 +0200
Jarkko Nikula wrote:
> On 10/30/2015 09:37 AM, Jisheng Zhang wrote:
> > Currently when i2c_msg index search is completed, TX_EMPTY interrupt
> > will be masked. But if the size of i2c_msg data is longer than the size
> > of the tx buffer, we still need TX_EMPTY interrupt, otherwise we will
> > get "controller timed out" error.
> > This patch fixes this issue by only masking TX_EMPTY if i2c_msg index
> > search is completed and write is not in progress.
> > Signed-off-by: Jisheng Zhang <jszhang at marvell.com>
> > ---
> > drivers/i2c/busses/i2c-designware-core.c | 7 ++++---
> > 1 file changed, 4 insertions(+), 3 deletions(-)
> > diff --git a/drivers/i2c/busses/i2c-designware-core.c b/drivers/i2c/busses/i2c-designware-core.c
> > index 7441cdc..a2eb212 100644
> > --- a/drivers/i2c/busses/i2c-designware-core.c
> > +++ b/drivers/i2c/busses/i2c-designware-core.c
> > @@ -542,10 +542,11 @@ i2c_dw_xfer_msg(struct dw_i2c_dev *dev)
> > }
> > /*
> > - * If i2c_msg index search is completed, we don't need TX_EMPTY
> > - * interrupt any more.
> > + * If i2c_msg index search is completed and writing is not in progress,
> > + * we don't need TX_EMPTY interrupt any more.
> > */
> > - if (dev->msg_write_idx == dev->msgs_num)
> > + if (dev->msg_write_idx == dev->msgs_num &&
> > + !(dev->status & STATUS_WRITE_IN_PROGRESS))
> > intr_mask &= ~DW_IC_INTR_TX_EMPTY;
> This looks a possible scenario here. What I'm wondering how is the
> transfer ending and what condition in i2c_dw_isr() causes the complete()
> Assuming we break the for loop in i2c_dw_xfer_msg() with buf_len > 0 and
> dev->msg_write_idx == dev->msgs_num how we get back inside the for loop
> for writing the remaining bytes and stop command?
This is a good question. After more consideration, I think the following
condition can't exist:
(msg_write_idx == dev->msgs_num) && (dev->status & STATUS_WRITE_IN_PROGRESS)
so this patch isn't necessary.
Thanks for your review,
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