On 27/07/15 12:55, Sifan Naeem wrote:
> This commit adds support for the I2C_M_IGNORE_NAK protocol
> modification.
>
> Such behaviour can only be implemented in atomic mode. So, if a
> transaction contains a message with such flag the drivers
> switches to atomic mode. The implementation consists simply in
> treating NAKs as ACKs.
>
> Signed-off-by: Sifan Naeem <sifan.naeem@xxxxxxxxxx>
Looks good,
Acked-by: James Hogan <james.hogan@xxxxxxxxxx>
Thanks!
James
> ---
> drivers/i2c/busses/i2c-img-scb.c | 15 ++++++++++-----
> 1 file changed, 10 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-img-scb.c b/drivers/i2c/busses/i2c-img-scb.c
> index 07a039c..31cd8c3 100644
> --- a/drivers/i2c/busses/i2c-img-scb.c
> +++ b/drivers/i2c/busses/i2c-img-scb.c
> @@ -767,7 +767,9 @@ static unsigned int img_i2c_atomic(struct img_i2c *i2c,
> next_cmd = CMD_RET_ACK;
> break;
> case CMD_RET_ACK:
> - if (i2c->line_status & LINESTAT_ACK_DET) {
> + if (i2c->line_status & LINESTAT_ACK_DET ||
> + (i2c->line_status & LINESTAT_NACK_DET &&
> + i2c->msg.flags & I2C_M_IGNORE_NAK)) {
> if (i2c->msg.len == 0) {
> next_cmd = CMD_GEN_STOP;
> } else if (i2c->msg.flags & I2C_M_RD) {
> @@ -1042,20 +1044,23 @@ static int img_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
> return -EIO;
>
> for (i = 0; i < num; i++) {
> - if (likely(msgs[i].len))
> - continue;
> /*
> * 0 byte reads are not possible because the slave could try
> * and pull the data line low, preventing a stop bit.
> */
> - if (unlikely(msgs[i].flags & I2C_M_RD))
> + if (!msgs[i].len && msgs[i].flags & I2C_M_RD)
> return -EIO;
> /*
> * 0 byte writes are possible and used for probing, but we
> * cannot do them in automatic mode, so use atomic mode
> * instead.
> + *
> + * Also, the I2C_M_IGNORE_NAK mode can only be implemented
> + * in atomic mode.
> */
> - atomic = true;
> + if (!msgs[i].len ||
> + (msgs[i].flags & I2C_M_IGNORE_NAK))
> + atomic = true;
> }
>
> ret = clk_prepare_enable(i2c->scb_clk);
>
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