From f7714b4e451bdcb7918b9aad14af22684ceac638 Mon Sep 17 00:00:00 2001 From: Abhishek Sahu Date: Mon, 12 Mar 2018 18:45:00 +0530 Subject: [PATCH 11/13] i2c: qup: send NACK for last read sub transfers MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Reviewed-by: Austin Christ Reviewed-by: Andy Gross Signed-off-by: Wolfram Sang --- drivers/i2c/busses/i2c-qup.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/drivers/i2c/busses/i2c-qup.c +++ b/drivers/i2c/busses/i2c-qup.c @@ -104,6 +104,7 @@ #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 */ @@ -606,7 +607,9 @@ static int qup_i2c_set_tags(u8 *tags, st 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; }