[PATCH V2 12/14] i3c: mipi-i3c-hci: Fix race in DMA error handling in interrupt context

[Adrian Hunter <adrian.hunter@intel.com>]

The DMA ring halts whenever a transfer encounters an error. The interrupt
handler previously attempted to detect this situation and restart the ring
if a transfer completed at the same time. However, this restart logic runs
entirely in interrupt context and is inherently racy: it interacts with
other paths manipulating the ring state, and fully serializing it within
the interrupt handler is not practical.

Move this error-recovery logic out of the interrupt handler and into the
transfer-processing path (i3c_hci_process_xfer()), where serialization and
state management are already controlled. Introduce a new optional I/O-ops
callback, handle_error(), invoked when a completed transfer reports an
error. For DMA operation, the implementation simply calls the existing
dequeue function, which safely aborts and restarts the ring when needed.

This removes the fragile ring-restart logic from the interrupt handler and
centralizes error handling where proper sequencing can be ensured.

Fixes: ccdb2e0e3b00d ("i3c: mipi-i3c-hci: Add Intel specific quirk to ring resuming")
Cc: stable@vger.kernel.org
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---


Changes in V2:

	None


 drivers/i3c/master/mipi-i3c-hci/core.c | 19 ++++++++++++----
 drivers/i3c/master/mipi-i3c-hci/dma.c  | 31 +++++++-------------------
 drivers/i3c/master/mipi-i3c-hci/hci.h  |  1 +
 3 files changed, 24 insertions(+), 27 deletions(-)

diff --git a/drivers/i3c/master/mipi-i3c-hci/core.c b/drivers/i3c/master/mipi-i3c-hci/core.c
index 4a80671536f0..b98952d12d7c 100644
--- a/drivers/i3c/master/mipi-i3c-hci/core.c
+++ b/drivers/i3c/master/mipi-i3c-hci/core.c
@@ -223,10 +223,21 @@ int i3c_hci_process_xfer(struct i3c_hci *hci, struct hci_xfer *xfer, int n)
 	if (ret)
 		return ret;
 
-	if (!wait_for_completion_timeout(done, timeout) &&
-	    hci->io->dequeue_xfer(hci, xfer, n)) {
-		dev_err(&hci->master.dev, "%s: timeout error\n", __func__);
-		return -ETIMEDOUT;
+	if (!wait_for_completion_timeout(done, timeout)) {
+		if (hci->io->dequeue_xfer(hci, xfer, n)) {
+			dev_err(&hci->master.dev, "%s: timeout error\n", __func__);
+			return -ETIMEDOUT;
+		}
+		return 0;
+	}
+
+	if (hci->io->handle_error) {
+		bool error = false;
+
+		for (int i = 0; i < n && !error; i++)
+			error = RESP_STATUS(xfer[i].response);
+		if (error)
+			return hci->io->handle_error(hci, xfer, n);
 	}
 
 	return 0;
diff --git a/drivers/i3c/master/mipi-i3c-hci/dma.c b/drivers/i3c/master/mipi-i3c-hci/dma.c
index 41b83f07fdab..e487ef52f6b4 100644
--- a/drivers/i3c/master/mipi-i3c-hci/dma.c
+++ b/drivers/i3c/master/mipi-i3c-hci/dma.c
@@ -609,6 +609,11 @@ static bool hci_dma_dequeue_xfer(struct i3c_hci *hci,
 	return did_unqueue;
 }
 
+static int hci_dma_handle_error(struct i3c_hci *hci, struct hci_xfer *xfer_list, int n)
+{
+	return hci_dma_dequeue_xfer(hci, xfer_list, n) ? -EIO : 0;
+}
+
 static void hci_dma_xfer_done(struct i3c_hci *hci, struct hci_rh_data *rh)
 {
 	u32 op1_val, op2_val, resp, *ring_resp;
@@ -870,29 +875,8 @@ static bool hci_dma_irq_handler(struct i3c_hci *hci)
 			hci_dma_xfer_done(hci, rh);
 		if (status & INTR_RING_OP)
 			complete(&rh->op_done);
-
-		if (status & INTR_TRANSFER_ABORT) {
-			u32 ring_status;
-
-			dev_notice_ratelimited(&hci->master.dev,
-				"Ring %d: Transfer Aborted\n", i);
-			mipi_i3c_hci_resume(hci);
-			ring_status = rh_reg_read(RING_STATUS);
-			if (!(ring_status & RING_STATUS_RUNNING) &&
-			    status & INTR_TRANSFER_COMPLETION &&
-			    status & INTR_TRANSFER_ERR) {
-				/*
-				 * Ring stop followed by run is an Intel
-				 * specific required quirk after resuming the
-				 * halted controller. Do it only when the ring
-				 * is not in running state after a transfer
-				 * error.
-				 */
-				rh_reg_write(RING_CONTROL, RING_CTRL_ENABLE);
-				rh_reg_write(RING_CONTROL, RING_CTRL_ENABLE |
-							   RING_CTRL_RUN_STOP);
-			}
-		}
+		if (status & INTR_TRANSFER_ABORT)
+			dev_dbg(&hci->master.dev, "Ring %d: Transfer Aborted\n", i);
 		if (status & INTR_IBI_RING_FULL)
 			dev_err_ratelimited(&hci->master.dev,
 				"Ring %d: IBI Ring Full Condition\n", i);
@@ -908,6 +892,7 @@ const struct hci_io_ops mipi_i3c_hci_dma = {
 	.cleanup		= hci_dma_cleanup,
 	.queue_xfer		= hci_dma_queue_xfer,
 	.dequeue_xfer		= hci_dma_dequeue_xfer,
+	.handle_error		= hci_dma_handle_error,
 	.irq_handler		= hci_dma_irq_handler,
 	.request_ibi		= hci_dma_request_ibi,
 	.free_ibi		= hci_dma_free_ibi,
diff --git a/drivers/i3c/master/mipi-i3c-hci/hci.h b/drivers/i3c/master/mipi-i3c-hci/hci.h
index 850016e3d4fe..9ac9d0e342f4 100644
--- a/drivers/i3c/master/mipi-i3c-hci/hci.h
+++ b/drivers/i3c/master/mipi-i3c-hci/hci.h
@@ -123,6 +123,7 @@ struct hci_io_ops {
 	bool (*irq_handler)(struct i3c_hci *hci);
 	int (*queue_xfer)(struct i3c_hci *hci, struct hci_xfer *xfer, int n);
 	bool (*dequeue_xfer)(struct i3c_hci *hci, struct hci_xfer *xfer, int n);
+	int (*handle_error)(struct i3c_hci *hci, struct hci_xfer *xfer, int n);
 	int (*request_ibi)(struct i3c_hci *hci, struct i3c_dev_desc *dev,
 			   const struct i3c_ibi_setup *req);
 	void (*free_ibi)(struct i3c_hci *hci, struct i3c_dev_desc *dev);
-- 
2.51.0


-- 
linux-i3c mailing list
linux-i3c@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-i3c