[PATCH V2 02/16] i3c: mipi-i3c-hci: Preserve RUN bit when aborting DMA ring

Adrian Hunter
2026-04-21T17:54:56Z

The MIPI I3C HCI specification does not require the DMA ring RUN bit
(RUN_STOP) to be cleared when issuing an ABORT. That allows the DMA ring
to continue to receive IBIs, although an IBI is anyway not lost because it
can be received once the ring restarts if the I3C device has not given up.
Note, currently ABORT is only used on a timeout error path so the change
has very little effect in practice. In the more common case of a transfer
error, the ring (bundle) operation is halted by the controller anyway.

Adjust the RING_CONTROL handling to set ABORT without clearing RUN_STOP,
bringing the driver into alignment with the specification.

Fixes: b795e68bf3073 ("i3c: mipi-i3c-hci: Correct RING_CTRL_ABORT handling in DMA dequeue")
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---

Changes in V2:

Improve commit message

drivers/i3c/master/mipi-i3c-hci/dma.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/i3c/master/mipi-i3c-hci/dma.c b/drivers/i3c/master/mipi-i3c-hci/dma.c
index e487ef52f6b4..4cd32e3afa7b 100644
--- a/drivers/i3c/master/mipi-i3c-hci/dma.c
+++ b/drivers/i3c/master/mipi-i3c-hci/dma.c
@@ -554,7 +554,7 @@ static bool hci_dma_dequeue_xfer(struct i3c_hci *hci,
if (ring_status & RING_STATUS_RUNNING) {
/* stop the ring */
reinit_completion(&rh->op_done);
- rh_reg_write(RING_CONTROL, RING_CTRL_ENABLE | RING_CTRL_ABORT);
+ rh_reg_write(RING_CONTROL, rh_reg_read(RING_CONTROL) | RING_CTRL_ABORT);
wait_for_completion_timeout(&rh->op_done, HZ);
ring_status = rh_reg_read(RING_STATUS);
if (ring_status & RING_STATUS_RUNNING) {