On 2016-05-11 21:48, Sricharan wrote:

Hi,

quoted

1. The current QCOM I2C driver code is failing for transfer length 
greater
than 255. This is happening due to improper segments length as the I2C 
DMA
segments can be maximum of 256 bytes.

2. The transfer length tlen was being initialized with 0 for 256 
bytes,
which is
being passed for DMA mappings resulting in improper DMA mapping 
length.

This patch fixes the above said problems by initializing the block 
count
with
the values calculated in qup_i2c_set_blk_data and calculating the

remaining

quoted

length for last DMA segment. Also, the block data length need to be
decremented after each transfer. Additionally, this patch corrects the
tlen
assignment for DMA mapping.

Signed-off-by: Abhishek Sahu <redacted>
---
 drivers/i2c/busses/i2c-qup.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/i2c/busses/i2c-qup.c 

b/drivers/i2c/busses/i2c-qup.c
index
8c2f1bc..6d6b7dc 100644

--- a/drivers/i2c/busses/i2c-qup.c
+++ b/drivers/i2c/busses/i2c-qup.c

@@ -651,23 +651,24 @@ static int qup_i2c_bam_do_xfer(struct

qup_i2c_dev *qup, struct i2c_msg *msg,
 	u8 *tags;

 	while (idx < num) {
-		blocks = (msg->len + limit) / limit;
-		rem = msg->len % limit;
 		tx_len = 0, len = 0, i = 0;

 		qup->is_last = (idx == (num - 1));

 		qup_i2c_set_blk_data(qup, msg);

+		blocks = qup->blk.count;
+		rem = msg->len - (blocks - 1) * limit;
+

      Same if we had blocks = (msg->len + limit - 1) / limit instead of 
the
above ?

Yes. We calculating this inside qup_i2c_set_blk_data and assigning the 
same value to
qup->blk.count so I am using this to avoid redundant arithmetic 
operations.

     Otherwise,
     Reviewed-by: Sricharan at codeaurora.org

Regards,
 Sricharan

-- 
Abhishek Sahu