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

On Wed, Jun 10, 2026 at 06:54:06PM -0700, [email protected] wrote:
> From: Adrian Ng Ho Yin <[email protected]>
>
> 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 <[email protected]>
> Signed-off-by: Tze Yee Ng <[email protected]>
> ---
>  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?

>
>  	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
>

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