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SubjectRe: [PATCH 10/12] i2c: qup: send NACK for last read sub transfers
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Tested on Centriq 2400

Reviewed-by: Austin Christ <austinwc@codeaurora.org>

On 2/3/2018 12:58 AM, Abhishek Sahu wrote:
> According to I2c specification, “If a master-receiver sends a
> repeated START condition, it sends a not-acknowledge (A) just
> before the repeated START condition”. QUP v2 supports sending
> of NACK without stop with QUP_TAG_V2_DATARD_NACK so added the
> same.
>
> Signed-off-by: Abhishek Sahu <absahu@codeaurora.org>
> ---
> 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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Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the
Code Aurora Forum, a Linux Foundation Collaborative Project.

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