On Mon, 9 Dec 2019 at 11:19, Michael Auchter <[email protected]> wrote: > > This fixes an issue that would cause I2C writes to timeout when the > number of bytes is a multiple of the FIFO depth (i.e. 16 bytes). > > Within the transfer loop, after writing the data register with a new > byte to transfer, if the transfer size equals the FIFO depth, the loop > pauses until the INTERRUPT_COMP bit asserts to indicate data has been > sent. This same check is performed after the loop as well to ensure data > has been transferred prior to returning. > > In the case where the amount of data to be written is a multiple of the > FIFO depth, the transfer loop would wait for the INTERRUPT_COMP bit to > assert after writing the final byte, and then wait for this bit to > assert once more. However, since the transfer has finished at this > point, no new data has been written to the data register, and hence > INTERRUPT_COMP will never assert. > > Fix this by only waiting for INTERRUPT_COMP in the transfer loop if > there's still data to be written. > > Signed-off-by: Michael Auchter <[email protected]> > --- > drivers/i2c/i2c-cdns.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/i2c/i2c-cdns.c b/drivers/i2c/i2c-cdns.c > index 2c0301ad08..ff3956d8c2 100644 > --- a/drivers/i2c/i2c-cdns.c > +++ b/drivers/i2c/i2c-cdns.c > @@ -265,7 +265,7 @@ static int cdns_i2c_write_data(struct i2c_cdns_bus > *i2c_bus, u32 addr, u8 *data, > > while (len-- && !is_arbitration_lost(regs)) { > writel(*(cur_data++), ®s->data); > - if (readl(®s->transfer_size) == CDNS_I2C_FIFO_DEPTH) { > + if (len && readl(®s->transfer_size) == > CDNS_I2C_FIFO_DEPTH) { > ret = cdns_i2c_wait(regs, CDNS_I2C_INTERRUPT_COMP | > CDNS_I2C_INTERRUPT_ARBLOST); > if (ret & CDNS_I2C_INTERRUPT_ARBLOST) > -- > 2.23.0 >
Reviewed-by: Simon Glass <[email protected]>
