[PATCH v2 1/3] i3c: master: dw: Report actual GET CCC payload length on success

[tze . yee . ng]

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;
 
 	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;
+	if (cmd->error == RESPONSE_ERROR_IBA_NACK)
 		ccc->err = I3C_ERROR_M2;
 
 	return ret;
-- 
2.43.7