linux-kernel - [PATCH 04/12] i2c: qup: schedule EOT and FLUSH tags at the end of transfer

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Date:   Sat,  3 Feb 2018 13:28:09 +0530
From:   Abhishek Sahu <absahu@...eaurora.org>
To:     Andy Gross <andy.gross@...aro.org>,
        Wolfram Sang <wsa@...-dreams.de>
Cc:     David Brown <david.brown@...aro.org>,
        Sricharan R <sricharan@...eaurora.org>,
        linux-arm-msm@...r.kernel.org, linux-soc@...r.kernel.org,
        linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org,
        Abhishek Sahu <absahu@...eaurora.org>
Subject: [PATCH 04/12] i2c: qup: schedule EOT and FLUSH tags at the end of transfer

A single BAM transfer can have multiple read and write messages.
The EOT and FLUSH tags should be scheduled at the end of BAM HW
descriptors. Since the READ and WRITE can be present in any order
so for some of the cases, these tags are not being written
correctly.

Signed-off-by: Abhishek Sahu <absahu@...eaurora.org>
---
 drivers/i2c/busses/i2c-qup.c | 54 ++++++++++++++++++++------------------------
 1 file changed, 24 insertions(+), 30 deletions(-)

diff --git a/drivers/i2c/busses/i2c-qup.c b/drivers/i2c/busses/i2c-qup.c
index bb83a2967..6357aff 100644
--- a/drivers/i2c/busses/i2c-qup.c
+++ b/drivers/i2c/busses/i2c-qup.c
@@ -560,7 +560,7 @@ static int qup_i2c_set_tags_smb(u16 addr, u8 *tags, struct qup_i2c_dev *qup,
 }
 
 static int qup_i2c_set_tags(u8 *tags, struct qup_i2c_dev *qup,
-			    struct i2c_msg *msg,  int is_dma)
+			    struct i2c_msg *msg)
 {
 	u16 addr = i2c_8bit_addr_from_msg(msg);
 	int len = 0;
@@ -601,11 +601,6 @@ static int qup_i2c_set_tags(u8 *tags, struct qup_i2c_dev *qup,
 	else
 		tags[len++] = data_len;
 
-	if ((msg->flags & I2C_M_RD) && last && is_dma) {
-		tags[len++] = QUP_BAM_INPUT_EOT;
-		tags[len++] = QUP_BAM_FLUSH_STOP;
-	}
-
 	return len;
 }
 
@@ -614,7 +609,7 @@ static int qup_i2c_issue_xfer_v2(struct qup_i2c_dev *qup, struct i2c_msg *msg)
 	int data_len = 0, tag_len, index;
 	int ret;
 
-	tag_len = qup_i2c_set_tags(qup->blk.tags, qup, msg, 0);
+	tag_len = qup_i2c_set_tags(qup->blk.tags, qup, msg);
 	index = msg->len - qup->blk.data_len;
 
 	/* only tags are written for read */
@@ -710,7 +705,7 @@ static int qup_i2c_bam_do_xfer(struct qup_i2c_dev *qup, struct i2c_msg *msg,
 			while (qup->blk.pos < blocks) {
 				tlen = (i == (blocks - 1)) ? rem : limit;
 				tags = &qup->start_tag.start[off + len];
-				len += qup_i2c_set_tags(tags, qup, msg, 1);
+				len += qup_i2c_set_tags(tags, qup, msg);
 				qup->blk.data_len -= tlen;
 
 				/* scratch buf to read the start and len tags */
@@ -738,17 +733,11 @@ static int qup_i2c_bam_do_xfer(struct qup_i2c_dev *qup, struct i2c_msg *msg,
 				return ret;
 
 			off += len;
-			/* scratch buf to read the BAM EOT and FLUSH tags */
-			ret = qup_sg_set_buf(&qup->brx.sg[rx_buf++],
-					     &qup->brx.tag.start[0],
-					     2, qup, DMA_FROM_DEVICE);
-			if (ret)
-				return ret;
 		} else {
 			while (qup->blk.pos < blocks) {
 				tlen = (i == (blocks - 1)) ? rem : limit;
 				tags = &qup->start_tag.start[off + tx_len];
-				len = qup_i2c_set_tags(tags, qup, msg, 1);
+				len = qup_i2c_set_tags(tags, qup, msg);
 				qup->blk.data_len -= tlen;
 
 				ret = qup_sg_set_buf(&qup->btx.sg[tx_buf++],
@@ -768,26 +757,31 @@ static int qup_i2c_bam_do_xfer(struct qup_i2c_dev *qup, struct i2c_msg *msg,
 			}
 			off += tx_len;
 
-			if (idx == (num - 1)) {
-				len = 1;
-				if (rx_buf) {
-					qup->btx.tag.start[0] =
-							QUP_BAM_INPUT_EOT;
-					len++;
-				}
-				qup->btx.tag.start[len - 1] =
-							QUP_BAM_FLUSH_STOP;
-				ret = qup_sg_set_buf(&qup->btx.sg[tx_buf++],
-						     &qup->btx.tag.start[0],
-						     len, qup, DMA_TO_DEVICE);
-				if (ret)
-					return ret;
-			}
 		}
 		idx++;
 		msg++;
 	}
 
+	/* schedule the EOT and FLUSH I2C tags */
+	len = 1;
+	if (rx_buf) {
+		qup->btx.tag.start[0] = QUP_BAM_INPUT_EOT;
+		len++;
+
+		/* scratch buf to read the BAM EOT and FLUSH tags */
+		ret = qup_sg_set_buf(&qup->brx.sg[rx_buf++],
+				     &qup->brx.tag.start[0],
+				     2, qup, DMA_FROM_DEVICE);
+		if (ret)
+			return ret;
+	}
+
+	qup->btx.tag.start[len - 1] = QUP_BAM_FLUSH_STOP;
+	ret = qup_sg_set_buf(&qup->btx.sg[tx_buf++], &qup->btx.tag.start[0],
+			     len, qup, DMA_TO_DEVICE);
+	if (ret)
+		return ret;
+
 	txd = dmaengine_prep_slave_sg(qup->btx.dma, qup->btx.sg, tx_buf,
 				      DMA_MEM_TO_DEV,
 				      DMA_PREP_INTERRUPT | DMA_PREP_FENCE);
-- 
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