Re: [PATCH v3 1/3] i3c: master: dw: Report actual GET CCC payload length on success

[NG, TZE YEE]

On 20/6/2026 3:21 am, Frank Li wrote:
> On Wed, Jun 10, 2026 at 06:54:06PM -0700, tze.yee.ng@xxxxxxxxxx wrote:
>> From: Adrian Ng Ho Yin <adrian.ho.yin.ng@xxxxxxxxxx>
>>
>> On successful GET CCC transfers, set dests[0].payload.len from
>> RESPONSE_PORT_DATA_LEN so the I3C core receives the number of bytes
>> actually read. Core helpers such as i3c_master_getmrl_locked() use
>> dest.payload.len after the transfer to interpret the response.
>>
>> Save the requested length in a local variable before programming the
>> hardware so the caller's buffer size is not conflated with the bytes
>> received.
>>
>> Signed-off-by: Adrian Ng Ho Yin <adrian.ho.yin.ng@xxxxxxxxxx>
>> Signed-off-by: Tze Yee Ng <tze.yee.ng@xxxxxxxxxx>
>> ---
>>   drivers/i3c/master/dw-i3c-master.c | 12 +++++++++---
>>   1 file changed, 9 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/i3c/master/dw-i3c-master.c b/drivers/i3c/master/dw-i3c-master.c
>> index 655693a2187e..06fdf8857b9c 100644
>> --- a/drivers/i3c/master/dw-i3c-master.c
>> +++ b/drivers/i3c/master/dw-i3c-master.c
>> @@ -751,21 +751,24 @@ static int dw_i3c_ccc_set(struct dw_i3c_master *master,
>>   static int dw_i3c_ccc_get(struct dw_i3c_master *master, struct i3c_ccc_cmd *ccc)
>>   {
>>   	struct dw_i3c_cmd *cmd;
>> +	u16 req_len;
>>   	int ret, pos;
>>
>>   	pos = dw_i3c_master_get_addr_pos(master, ccc->dests[0].addr);
>>   	if (pos < 0)
>>   		return pos;
>>
>> +	req_len = ccc->dests[0].payload.len;
>> +
>>   	struct dw_i3c_xfer *xfer __free(kfree) = dw_i3c_master_alloc_xfer(master, 1);
>>   	if (!xfer)
>>   		return -ENOMEM;
>>
>>   	cmd = xfer->cmds;
>>   	cmd->rx_buf = ccc->dests[0].payload.data;
>> -	cmd->rx_len = ccc->dests[0].payload.len;
>> +	cmd->rx_len = req_len;
>>
>> -	cmd->cmd_hi = COMMAND_PORT_ARG_DATA_LEN(ccc->dests[0].payload.len) |
>> +	cmd->cmd_hi = COMMAND_PORT_ARG_DATA_LEN(req_len) |
>>   		      COMMAND_PORT_TRANSFER_ARG;
> 
> not sure how req_len help it. Prevously everything copy into cmd.  now copy
> req_len then copy to cmd,
> 
> No difference?
> 
You are correct. Saving req_len here does nothing useful as payload.len 
is never getting overwritten. I will drop req_len in v4; keep using 
ccc->dests[0].payload.len when setting up cmd->rx_len / 
COMMAND_PORT_ARG_DATA_LEN.>>
>>   	cmd->cmd_lo = COMMAND_PORT_READ_TRANSFER |
>> @@ -780,7 +783,10 @@ static int dw_i3c_ccc_get(struct dw_i3c_master *master, struct i3c_ccc_cmd *ccc)
>>   		dw_i3c_master_dequeue_xfer(master, xfer);
>>
>>   	ret = xfer->ret;
>> -	if (xfer->cmds[0].error == RESPONSE_ERROR_IBA_NACK)
>> +	cmd = &xfer->cmds[0];
>> +	if (!ret)
>> +		ccc->dests[0].payload.len = cmd->rx_len;
> 
> Only this line is validate.
> 
> Frank
>> +	if (cmd->error == RESPONSE_ERROR_IBA_NACK)
>>   		ccc->err = I3C_ERROR_M2;
>>
>>   	return ret;
>> --
>> 2.43.7
>>