[PATCH v3] slimbus: qcom-ngd-ctrl: Implement disable_stream callback

[PATCH v3] slimbus: qcom-ngd-ctrl: Implement disable_stream callback

[Viken Dadhaniya]

Switching a channel to a new frequency without first disabling the stream
causes the channel to be re-enabled without a clean shutdown, leading to a
crash on the DSP subsystem.

Implement qcom_slim_ngd_disable_stream() so clients can properly close a
channel before switching to a new frequency.

Acked-by: Mukesh Savaliya <mukesh.savaliya@oss.qualcomm.com>
Signed-off-by: Viken Dadhaniya <viken.dadhaniya@oss.qualcomm.com>
---
Changes in v3:
- Handle -EREMOTEIO as success during stream disable.
- Drop copyright update changes.
- Link to v2: https://patch.msgid.link/20260810-slim-disable-stream-support-v2-1-c2e8fcc3c99d@oss.qualcomm.com

Changes in v2:
- Rewrite commit description for clarity.
- Fix initializers: use { 0 } instead of {0} and {0,}.
- Use reverse christmas tree ordering for local variable declarations.
- Replace open-coded shift/mask with FIELD_PREP() and GENMASK-based defines.
- Add SLIM_MSG_HDR_LEN macro to replace magic number +4 in txn.rl assignments.
- Fix dev_err format strings: add spaces after colons and commas.
- Update enum slim_ch_control comment to kernel-doc format with @member tags.
- Link to v1: https://lore.kernel.org/linux-arm-msm/247e4ce7-1ba2-43b8-8a11-ec70f99a4fc1@linaro.org/T/#m3b50aa43a6493f8d3b607b1607b37bf14b199f69
---
 drivers/slimbus/qcom-ngd-ctrl.c | 78 +++++++++++++++++++++++++++++++++++++++++
 drivers/slimbus/slimbus.h       | 12 +++++++
 2 files changed, 90 insertions(+)

diff --git a/drivers/slimbus/qcom-ngd-ctrl.c b/drivers/slimbus/qcom-ngd-ctrl.c
index eb0ccb31e907..f0a402069aea 100644
--- a/drivers/slimbus/qcom-ngd-ctrl.c
+++ b/drivers/slimbus/qcom-ngd-ctrl.c
@@ -2,6 +2,7 @@
 // Copyright (c) 2011-2017, The Linux Foundation. All rights reserved.
 // Copyright (c) 2018, Linaro Limited
 
+#include <linux/bitfield.h>
 #include <linux/irq.h>
 #include <linux/kernel.h>
 #include <linux/init.h>
@@ -87,6 +88,10 @@
 #define SLIM_ROOT_FREQ	24576000
 #define LADDR_RETRY	5
 
+#define SLIM_CHAN_CTRL_CMD		GENMASK(7, 6)
+#define SLIM_CHAN_CTRL_LADDR		GENMASK(4, 0)
+#define SLIM_MSG_HDR_LEN		4
+
 /* Per spec.max 40 bytes per received message */
 #define SLIM_MSGQ_BUF_LEN	40
 #define QCOM_SLIM_NGD_DESC_NUM	32
@@ -1086,6 +1091,78 @@ static int qcom_slim_ngd_enable_stream(struct slim_stream_runtime *rt)
 	return ret;
 }
 
+static int qcom_slim_ngd_disable_stream(struct slim_stream_runtime *rt)
+{
+	struct slim_device *sdev = rt->dev;
+	struct slim_controller *ctrl = sdev->ctrl;
+	struct slim_msg_txn txn = { 0 };
+	struct slim_val_inf msg = { 0 };
+	u8 wbuf[SLIM_MSGQ_BUF_LEN];
+	u8 rbuf[SLIM_MSGQ_BUF_LEN];
+	int i, ret;
+
+	txn.mt = SLIM_MSG_MT_DEST_REFERRED_USER;
+	txn.dt = SLIM_MSG_DEST_LOGICALADDR;
+	txn.la = SLIM_LA_MGR;
+	txn.ec = 0;
+	txn.msg = &msg;
+	txn.msg->num_bytes = 0;
+	txn.msg->wbuf = wbuf;
+	txn.msg->rbuf = rbuf;
+
+	for (i = 0; i < rt->num_ports; i++) {
+		struct slim_port *port = &rt->ports[i];
+
+		if (txn.msg->num_bytes == 0) {
+			wbuf[txn.msg->num_bytes++] =
+				FIELD_PREP(SLIM_CHAN_CTRL_CMD, SLIM_CH_REMOVE) |
+				FIELD_PREP(SLIM_CHAN_CTRL_LADDR, sdev->laddr);
+
+			ret = slim_alloc_txn_tid(ctrl, &txn);
+			if (ret) {
+				dev_err(&sdev->dev, "Fail to allocate TID ret:%d\n", ret);
+				return ret;
+			}
+			wbuf[txn.msg->num_bytes++] = txn.tid;
+		}
+		wbuf[txn.msg->num_bytes++] = port->ch.id;
+	}
+
+	txn.mc = SLIM_USR_MC_CHAN_CTRL;
+	txn.rl = txn.msg->num_bytes + SLIM_MSG_HDR_LEN;
+	ret = qcom_slim_ngd_xfer_msg_sync(ctrl, &txn);
+	if (ret) {
+		slim_free_txn_tid(ctrl, &txn);
+		/* Controller restarting, the channels are gone anyway */
+		if (ret == -EREMOTEIO)
+			return 0;
+		dev_err(&sdev->dev, "TX timed out: MC: 0x%x, mt: 0x%x, laddr: 0x%x, ret: %d\n",
+			txn.mc, txn.mt, sdev->laddr, ret);
+		return ret;
+	}
+
+	txn.mc = SLIM_USR_MC_RECONFIG_NOW;
+	txn.msg->num_bytes = 2;
+	wbuf[1] = sdev->laddr;
+	txn.rl = txn.msg->num_bytes + SLIM_MSG_HDR_LEN;
+
+	ret = slim_alloc_txn_tid(ctrl, &txn);
+	if (ret) {
+		dev_err(&sdev->dev, "Fail to allocate TID ret:%d\n", ret);
+		return ret;
+	}
+
+	wbuf[0] = txn.tid;
+	ret = qcom_slim_ngd_xfer_msg_sync(ctrl, &txn);
+	if (ret) {
+		slim_free_txn_tid(ctrl, &txn);
+		dev_err(&sdev->dev, "TX timed out: MC: 0x%x, mt: 0x%x, laddr: 0x%x, ret: %d\n",
+			txn.mc, txn.mt, sdev->laddr, ret);
+	}
+
+	return ret;
+}
+
 static int qcom_slim_ngd_get_laddr(struct slim_controller *ctrl,
 				   struct slim_eaddr *ea, u8 *laddr)
 {
@@ -1625,6 +1702,7 @@ static int qcom_slim_ngd_ctrl_probe(struct platform_device *pdev)
 	ctrl->ctrl.clkgear = SLIM_MAX_CLK_GEAR;
 	ctrl->ctrl.get_laddr = qcom_slim_ngd_get_laddr;
 	ctrl->ctrl.enable_stream = qcom_slim_ngd_enable_stream;
+	ctrl->ctrl.disable_stream = qcom_slim_ngd_disable_stream;
 	ctrl->ctrl.xfer_msg = qcom_slim_ngd_xfer_msg;
 	ctrl->ctrl.wakeup = NULL;
 	ctrl->state = QCOM_SLIM_NGD_CTRL_DOWN;
diff --git a/drivers/slimbus/slimbus.h b/drivers/slimbus/slimbus.h
index 3a03993c3ac8..8e34f30601d3 100644
--- a/drivers/slimbus/slimbus.h
+++ b/drivers/slimbus/slimbus.h
@@ -316,6 +316,18 @@ enum slim_transport_protocol {
 	SLIM_PROTO_EXT_HALF_DUP,
 };
 
+/**
+ * enum slim_ch_control: Channel control.
+ * @SLIM_CH_ACTIVATE: Schedules channel or group of channels in the TDM frame.
+ * @SLIM_CH_SUSPEND: Keeps the TDM schedule but halts data transfer.
+ * @SLIM_CH_REMOVE: Drops the channel or group from the TDM frame.
+ */
+enum slim_ch_control {
+	SLIM_CH_ACTIVATE,
+	SLIM_CH_SUSPEND,
+	SLIM_CH_REMOVE,
+};
+
 /**
  * struct slim_stream_runtime  - SLIMbus stream runtime instance
  *

---
base-commit: 4c253ac4b29b8c6cc6fdef8f92d4facde62e63b9
change-id: 20260803-slim-disable-stream-support-43599401607f

Best regards,
--  
Viken Dadhaniya <viken.dadhaniya@oss.qualcomm.com>

Re: [PATCH v3] slimbus: qcom-ngd-ctrl: Implement disable_stream callback

[Srinivas Kandagatla]

On Fri, 25 Sep 2026 14:52:49 +0530, Viken Dadhaniya wrote:
> Switching a channel to a new frequency without first disabling the stream
> causes the channel to be re-enabled without a clean shutdown, leading to a
> crash on the DSP subsystem.
> 
> Implement qcom_slim_ngd_disable_stream() so clients can properly close a
> channel before switching to a new frequency.
> 
> [...]

Applied, thanks!

[1/1] slimbus: qcom-ngd-ctrl: Implement disable_stream callback
      commit: 82d873c864b033af83f2b8f34da025d08e4e886d

Best regards,
-- 
Srinivas Kandagatla <srini@kernel.org>