Re: [PATCH 10/12] i2c: qup: send NACK for last read sub transfers

[Christ, Austin]

Tested on Centriq 2400

Reviewed-by: Austin Christ <austinwc@xxxxxxxxxxxxxx>

On 2/3/2018 12:58 AM, Abhishek Sahu wrote:
> According to I2c specification, âIf a master-receiver sends a
> repeated START condition, it sends a not-acknowledge (A) just
> before the repeated START conditionâ. QUP v2 supports sending
> of NACK without stop with QUP_TAG_V2_DATARD_NACK so added the
> same.
>
> Signed-off-by: Abhishek Sahu <absahu@xxxxxxxxxxxxxx>
> ---
>   drivers/i2c/busses/i2c-qup.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/i2c/busses/i2c-qup.c b/drivers/i2c/busses/i2c-qup.c
> index ba717bb..edea3b9 100644
> --- a/drivers/i2c/busses/i2c-qup.c
> +++ b/drivers/i2c/busses/i2c-qup.c
> @@ -113,6 +113,7 @@
>   #define QUP_TAG_V2_DATAWR              0x82
>   #define QUP_TAG_V2_DATAWR_STOP         0x83
>   #define QUP_TAG_V2_DATARD              0x85
> +#define QUP_TAG_V2_DATARD_NACK         0x86
>   #define QUP_TAG_V2_DATARD_STOP         0x87
>   
>   /* Status, Error flags */
> @@ -609,7 +610,9 @@ static int qup_i2c_set_tags(u8 *tags, struct qup_i2c_dev *qup,
>   			tags[len++] = QUP_TAG_V2_DATAWR_STOP;
>   	} else {
>   		if (msg->flags & I2C_M_RD)
> -			tags[len++] = QUP_TAG_V2_DATARD;
> +			tags[len++] = qup->blk.pos == (qup->blk.count - 1) ?
> +				      QUP_TAG_V2_DATARD_NACK :
> +				      QUP_TAG_V2_DATARD;
>   		else
>   			tags[len++] = QUP_TAG_V2_DATAWR;
>   	}

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