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SubjectRe: [PATCH 04/12] i2c: qup: schedule EOT and FLUSH tags at the end of transfer
On 2018-02-15 20:01, Sricharan R wrote:
> Hi Abhishek,
>
> On 2/3/2018 1:28 PM, Abhishek Sahu wrote:
>> 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@codeaurora.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++;
>> }
>
> While here, can you please split above the if, else in to two
> separate functions ?
> and probably one more function for handling the NACK case down below.
> The function
> size at the moment is too big.
>

Sure. Already I split this function into 2 functions in
[PATCH 09/12] i2c: qup: fix buffer overflow for multiple msg of maximum
xfer len
which is making function size smaller. I will check if I can split in
more
functions.

>>
>> + /* 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;
>> +
>
> May be you can change the commit to make it explicit to say what is
> being
> fixed, like "current code is broken when there is sequence of
> wr,rd,wr" like that.
> Agree on this fix otherwise.
>

Thanks. I will update the commit message to include the failure
case which will give clear idea.

Thanks,
Abhishek

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