[PATCH 02/12] i3c: mipi-i3c-hci: Fix Hot-Join NACK

From: Adrian Hunter <adrian.hunter@intel.com>
To: alexandre.belloni@bootlin.com
Cc: Frank.Li@nxp.com, linux-i3c@lists.infradead.org
Subject: [PATCH 02/12] i3c: mipi-i3c-hci: Fix Hot-Join NACK
Date: Fri, 27 Feb 2026 16:11:39 +0200	[thread overview]
Message-ID: <20260227141149.184980-3-adrian.hunter@intel.com> (raw)
In-Reply-To: <20260227141149.184980-1-adrian.hunter@intel.com>

The MIPI I3C HCI host controller driver does not implement Hot-Join
handling, yet Hot-Join response control defaults to allowing devices to
Hot‑Join the bus.  Configure HC_CONTROL_HOT_JOIN_CTRL to NACK all Hot‑Join
attempts.

Fixes: 9ad9a52cce282 ("i3c/master: introduce the mipi-i3c-hci driver")
Cc: stable@vger.kernel.org
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---
 drivers/i3c/master/mipi-i3c-hci/core.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/i3c/master/mipi-i3c-hci/core.c b/drivers/i3c/master/mipi-i3c-hci/core.c
index dbe93df0c70e..4877a321edf9 100644
--- a/drivers/i3c/master/mipi-i3c-hci/core.c
+++ b/drivers/i3c/master/mipi-i3c-hci/core.c
@@ -152,7 +152,8 @@ static int i3c_hci_bus_init(struct i3c_master_controller *m)
 	if (hci->quirks & HCI_QUIRK_RESP_BUF_THLD)
 		amd_set_resp_buf_thld(hci);
 
-	reg_set(HC_CONTROL, HC_CONTROL_BUS_ENABLE);
+	/* Enable bus with Hot-Join disabled */
+	reg_set(HC_CONTROL, HC_CONTROL_BUS_ENABLE | HC_CONTROL_HOT_JOIN_CTRL);
 	dev_dbg(&hci->master.dev, "HC_CONTROL = %#x", reg_read(HC_CONTROL));
 
 	return 0;
@@ -764,7 +765,8 @@ static int i3c_hci_runtime_resume(struct device *dev)
 
 	hci->io->resume(hci);
 
-	reg_set(HC_CONTROL, HC_CONTROL_BUS_ENABLE);
+	/* Enable bus with Hot-Join disabled */
+	reg_set(HC_CONTROL, HC_CONTROL_BUS_ENABLE | HC_CONTROL_HOT_JOIN_CTRL);
 
 	return 0;
 }
-- 
2.51.0


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