On Wed, Jul 31, 2019 at 02:37:35PM +0200, Ludovic Desroches wrote:
> Hi,
>
> On Mon, Jul 22, 2019 at 08:55:27PM +0200, Michał Mirosław wrote:
> >
> > Driver was not disabling TXRDY interrupt after last TX byte.
> > This caused interrupt storm until transfer timeouts for slow
> > or broken device on the bus. The patch fixes the interrupt storm
> > on my SAMA5D2-based board.
> >
> > Cc: stable@xxxxxxxxxxxxxxx # 5.2.x
> > [v5.2 introduced file split; the patch should apply to i2c-at91.c before the split]
> > Fixes: fac368a0404 ("i2c: at91: add new driver")
> > Signed-off-by: Michał Mirosław <mirq-linux@xxxxxxxxxxxx>
> Acked-by: Ludovic Desroches <ludovic.desroches@xxxxxxxxxxxxx>
Tested-by: Raag Jadav <raagjadav@xxxxxxxxx>
>
> Sounds good to me as AT91_TWI_TXRDY is only used to send the next byte.
>
> Raag, you added you in the copy list as it seems close to your issue. I am
> really sorry, I didn't have time to go further with your issue. Is this
> patch solves your issue?
Yes, although I had a v2 ready to send out with similar changes,
this patch does the job as well.
Cheers,
Raag
>
> Thanks for this patch.
>
> Ludovic
>
> > ---
> > drivers/i2c/busses/i2c-at91-master.c | 9 +++++----
> > 1 file changed, 5 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/i2c/busses/i2c-at91-master.c b/drivers/i2c/busses/i2c-at91-master.c
> > index e87232f2e708..a3fcc35ffd3b 100644
> > --- a/drivers/i2c/busses/i2c-at91-master.c
> > +++ b/drivers/i2c/busses/i2c-at91-master.c
> > @@ -122,9 +122,11 @@ static void at91_twi_write_next_byte(struct at91_twi_dev *dev)
> > writeb_relaxed(*dev->buf, dev->base + AT91_TWI_THR);
> >
> > /* send stop when last byte has been written */
> > - if (--dev->buf_len == 0)
> > + if (--dev->buf_len == 0) {
> > if (!dev->use_alt_cmd)
> > at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_STOP);
> > + at91_twi_write(dev, AT91_TWI_IDR, AT91_TWI_TXRDY);
> > + }
> >
> > dev_dbg(dev->dev, "wrote 0x%x, to go %zu\n", *dev->buf, dev->buf_len);
> >
> > @@ -542,9 +544,8 @@ static int at91_do_twi_transfer(struct at91_twi_dev *dev)
> > } else {
> > at91_twi_write_next_byte(dev);
> > at91_twi_write(dev, AT91_TWI_IER,
> > - AT91_TWI_TXCOMP |
> > - AT91_TWI_NACK |
> > - AT91_TWI_TXRDY);
> > + AT91_TWI_TXCOMP | AT91_TWI_NACK |
> > + (dev->buf_len ? AT91_TWI_TXRDY : 0));
> > }
> > }
> >
> > --
> > 2.20.1
> >
