i3c: mipi-i3c-hci: fix IBI payload length calculation for final status

[ Upstream commit d35a6db ]

In DMA mode, the IBI status descriptor encodes the payload using
CHUNKS (number of chunks) and DATA_LENGTH (valid bytes in the last
chunk). All preceding chunks are implicitly full-sized.

The current code accumulates full chunk sizes for non-final status
descriptors, but for the final status descriptor it only adds
DATA_LENGTH. This ignores the contribution of the preceding full
chunks described by the same final status entry.

As a result, the computed IBI payload length is truncated whenever
the final status spans multiple chunks. For example, with a chunk
size of 4 bytes, CHUNKS=2 and DATA_LENGTH=1 should result in a total
payload size of 5 bytes, but the current code reports only 1 byte.

Fix the calculation by adding the size of (CHUNKS - 1) full chunks
plus DATA_LENGTH for the last chunk.

Fixes: 9ad9a52 ("i3c/master: introduce the mipi-i3c-hci driver")
Signed-off-by: Billy Tsai <billy_tsai@aspeedtech.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://patch.msgid.link/20260407-i3c-hci-dma-v2-1-a583187b9d22@aspeedtech.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: billy-tsai

drivers/i3c/master/mipi-i3c-hci/dma.c

@@ -645,7 +645,10 @@ static void hci_dma_process_ibi(struct i3c_hci *hci, struct hci_rh_data *rh)
 		if (!(ibi_status & IBI_LAST_STATUS)) {
 			ibi_size += chunks * rh->ibi_chunk_sz;
 		} else {
-			ibi_size += FIELD_GET(IBI_DATA_LENGTH, ibi_status);
+			if (chunks) {
+				ibi_size += (chunks - 1) * rh->ibi_chunk_sz;
+				ibi_size += FIELD_GET(IBI_DATA_LENGTH, ibi_status);
+			}
 			last_ptr = ptr;
 			break;
 		}