[PATCH v1 2/2] i2c: microchip: fix erroneous late ack send

[Conor.Dooley at microchip.com]

On 26/10/2022 08:49, Conor Dooley wrote:
> A late ack is currently being sent at the end of a transfer due to
> incorrect logic in mchp_corei2c_empty_rx(). Currently the Assert Ack
> bit is being written to the controller's control reg after the last
> byte has been received, causing it to sent another byte with the ack.
> Instead, the AA flag should be written to the control register when
> the penultimate byte is read so it is sent out for the last byte.
> 
> Reported-by: Andreas Buerkler <andreas.buerkler at enclustra.com>
> Fixes: 0dc0d1e094 ("i2c: Add Microchip PolarFire SoC I2C driver")
> Fixes: 0190d48488 ("i2c: microchip: fix ack sending logic")

I had removed this fixes tag but I must have aborted the rebase
in which I did. If nothing else needs changing, please drop it,
otherwise I'll remove it if/when I send a v2.

Thanks,
Conor.

> Signed-off-by: Conor Dooley <conor.dooley at microchip.com>
> ---
>   drivers/i2c/i2c-microchip.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/i2c/i2c-microchip.c b/drivers/i2c/i2c-microchip.c
> index 3a27459386..d82b80f535 100644
> --- a/drivers/i2c/i2c-microchip.c
> +++ b/drivers/i2c/i2c-microchip.c
> @@ -224,7 +224,7 @@ static void mpfs_i2c_empty_rx(struct mpfs_i2c_bus *bus)
>   		bus->msg_len--;
>   	}
>   
> -	if (bus->msg_len == 0) {
> +	if (bus->msg_len <= 1) {
>   		ctrl = readl(bus->base + MPFS_I2C_CTRL);
>   		ctrl &= ~CTRL_AA;
>   		writel(ctrl, bus->base + MPFS_I2C_CTRL);