On Tue, Mar 05, 2019 at 06:54:34PM +0100, Wolfram Sang wrote:
> When sending with DMA, the driver transfers the first byte with PIO (as
> documented). However, it started DMA right after the first byte was
> written. This worked, but was not according to the datasheet which
> suggests to wait until data register was empty again. Implement this.
>
> Signed-off-by: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
Reviewed-by: Simon Horman <horms+renesas@xxxxxxxxxxxx>
> ---
> drivers/i2c/busses/i2c-rcar.c | 11 ++++-------
> 1 file changed, 4 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-rcar.c b/drivers/i2c/busses/i2c-rcar.c
> index 7e009febe97f..63286b3cc69b 100644
> --- a/drivers/i2c/busses/i2c-rcar.c
> +++ b/drivers/i2c/busses/i2c-rcar.c
> @@ -480,6 +480,10 @@ static void rcar_i2c_irq_send(struct rcar_i2c_priv *priv, u32 msr)
> if (!(msr & MDE))
> return;
>
> + /* Check if DMA can be enabled and take over */
> + if (priv->pos == 1 && rcar_i2c_dma(priv))
> + return;
> +
> if (priv->pos < msg->len) {
> /*
> * Prepare next data to ICRXTX register.
> @@ -490,13 +494,6 @@ static void rcar_i2c_irq_send(struct rcar_i2c_priv *priv, u32 msr)
> */
> rcar_i2c_write(priv, ICRXTX, msg->buf[priv->pos]);
> priv->pos++;
> -
> - /*
> - * Try to use DMA to transmit the rest of the data if
> - * address transfer phase just finished.
> - */
> - if (msr & MAT)
> - rcar_i2c_dma(priv);
> } else {
> /*
> * The last data was pushed to ICRXTX on _PREV_ empty irq.
> --
> 2.11.0
>
