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SubjectRe: [PATCH v2 2/2] i2c: qup: support SMBus block read
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Hi Sricharan,


On 5/18/2016 1:06 AM, Sricharan wrote:
> Hi,
>
> <snip..>
>
>> +static bool qup_i2c_check_msg_len(struct i2c_msg *msg) {
>> + return ((msg->flags & I2C_M_RD) && (msg->flags &
>> I2C_M_RECV_LEN)); }
>> +
>> +static int qup_i2c_set_tags_smb(u16 addr, u8 *tags, struct qup_i2c_dev
>> *qup,
>> + struct i2c_msg *msg)
>> +{
>> + int len = 0;
>> + int data_len = qup_i2c_get_data_len(qup);
>> +
>> + if (msg->len > 1) {
>> + tags[len++] = QUP_TAG_V2_DATARD_STOP;
>> + tags[len++] = data_len - 1;
>> + } else {
> So we hit this else part for msg->len = 1 and this case blk.pos = 0
> will always be true right ?
Yes, will fix that in V3.
>
>> + if (qup->blk.pos == 0) {
>> + tags[len++] = QUP_TAG_V2_START;
>> + tags[len++] = addr & 0xff;
>> +
>> + if (msg->flags & I2C_M_TEN)
>> + tags[len++] = addr >> 8;
>> + }
>> +
>> + tags[len++] = QUP_TAG_V2_DATARD;
>> + /* 0 implies 256 bytes */
>> + if (data_len == QUP_READ_LIMIT)
>> + tags[len++] = 0;
>> + else
>> + tags[len++] = data_len;
>> + }
> Even data_len will always be '1' right ?
Yes, but here preferably we use a variable than a number without a context.
>> + return len;
>> +}
>> +
>> static int qup_i2c_set_tags(u8 *tags, struct qup_i2c_dev *qup,
>> struct i2c_msg *msg, int is_dma) { @@ -526,6
>> +559,10 @@ static int qup_i2c_set_tags(u8 *tags, struct qup_i2c_dev *qup,
>>
>> int last = (qup->blk.pos == (qup->blk.count - 1)) && (qup->is_last);
>>
>> + /* Handle tags for SMBus block read */
>> + if (qup_i2c_check_msg_len(msg))
>> + return qup_i2c_set_tags_smb(addr, tags, qup, msg);
>> +
>> if (qup->blk.pos == 0) {
>> tags[len++] = QUP_TAG_V2_START;
>> tags[len++] = addr & 0xff;
>> @@ -1065,9 +1102,17 @@ static int qup_i2c_read_fifo_v2(struct
>> qup_i2c_dev *qup,
>> struct i2c_msg *msg)
>> {
>> u32 val;
>> - int idx, pos = 0, ret = 0, total;
>> + int idx, pos = 0, ret = 0, total, msg_offset = 0;
>>
>> + /*
>> + * If the message length is already read in
>> + * the first byte of the buffer, account for
>> + * that by setting the offset
>> + */
>> + if (qup_i2c_check_msg_len(msg) && (msg->len > 1))
>> + msg_offset = 1;
>> total = qup_i2c_get_data_len(qup);
>> + total -= msg_offset;
>>
>> /* 2 extra bytes for read tags */
>> while (pos < (total + 2)) {
>> @@ -1087,8 +1132,8 @@ static int qup_i2c_read_fifo_v2(struct
>> qup_i2c_dev *qup,
>>
>> if (pos >= (total + 2))
>> goto out;
>> -
>> - msg->buf[qup->pos++] = val & 0xff;
>> + msg->buf[qup->pos+msg_offset] = val & 0xff;
> A space around '+' ?
Thanks, will fix that.
>
>> + qup->pos++;
>> }
>> }
>>
>> @@ -1128,6 +1173,22 @@ static int qup_i2c_read_one_v2(struct
>> qup_i2c_dev *qup, struct i2c_msg *msg)
>> goto err;
>>
>> qup->blk.pos++;
>> +
>> + /* Handle SMBus block read length */
>> + if (qup_i2c_check_msg_len(msg) && (msg->len == 1)) {
>> + if (msg->buf[0] > I2C_SMBUS_BLOCK_MAX) {
>> + ret = -EPROTO;
>> + goto err;
>> + }
>> + msg->len += msg->buf[0];
>> + qup->pos = 0;
>> + qup_i2c_set_read_mode_v2(qup, msg->len);
>> + qup_i2c_issue_xfer_v2(qup, msg);
>> + ret = qup_i2c_wait_for_complete(qup, msg);
>> + if (ret)
>> + goto err;
> Is the issue_xfer_v2 needed inside this here ?
No, qup_i2c_issue_xfer_v2 is needed so that we read rest of the data
that is indicated by the length we read earlier.
>
>> + qup_i2c_set_blk_data(qup, msg);
>> + }
>> } while (qup->blk.pos < qup->blk.count);
> Regards,
> Sricharan

Thanks,
Naveen
>

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