Re: [PATCH v2] slimbus: qcom-ngd-ctrl: Implement disable_stream callback

[Viken Dadhaniya]

On 9/18/2026 4:05 AM, Srinivas Kandagatla wrote:
> 
> 
> On 8/10/26 6:52 PM, 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.
>>
>> Signed-off-by: Viken Dadhaniya <viken.dadhaniya@xxxxxxxxxxxxxxxx>
>> ---
>> 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@xxxxxxxxxx/T/#m3b50aa43a6493f8d3b607b1607b37bf14b199f69
>> ---
>>  drivers/slimbus/qcom-ngd-ctrl.c | 82 ++++++++++++++++++++++++++++++++++++++++-
>>  drivers/slimbus/slimbus.h       | 13 +++++++
>>  2 files changed, 93 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/slimbus/qcom-ngd-ctrl.c b/drivers/slimbus/qcom-ngd-ctrl.c
>> index 934c44c5bc1a..30d6ac52072b 100644
>> --- a/drivers/slimbus/qcom-ngd-ctrl.c
>> +++ b/drivers/slimbus/qcom-ngd-ctrl.c
>> @@ -1,7 +1,11 @@
>>  // SPDX-License-Identifier: GPL-2.0
>> -// Copyright (c) 2011-2017, The Linux Foundation. All rights reserved.
>> -// Copyright (c) 2018, Linaro Limited
>> +/*
>> + * Copyright (c) 2011-2017, The Linux Foundation. All rights reserved.
>> + * Copyright (c) 2018, Linaro Limited
>> + * Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
> 
> Why are you modifying this?

Updated the copyright header to use a single multiline comment, including
the Qualcomm copyright attribution.

> 
>> + */
>>  
>> +#include <linux/bitfield.h>
>>  #include <linux/irq.h>
>>  #include <linux/kernel.h>
>>  #include <linux/init.h>
>> @@ -86,6 +90,10 @@
>>  #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
>> @@ -1085,6 +1093,75 @@ 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);
>> +		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)
>>  {
>> @@ -1624,6 +1701,7 @@ 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 00a7f112574b..c1137e8aedf4 100644
>> --- a/drivers/slimbus/slimbus.h
>> +++ b/drivers/slimbus/slimbus.h
>> @@ -1,6 +1,7 @@
>>  /* SPDX-License-Identifier: GPL-2.0 */
>>  /*
>>   * Copyright (c) 2011-2017, The Linux Foundation
>> + * Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
> same here, why?

Updated the copyright header to use a single multiline comment, including
the Qualcomm copyright attribution.

>>   */
>>  
>>  #ifndef _DRIVERS_SLIMBUS_H
>> @@ -316,6 +317,18 @@ 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: 415606a7be939835db9b0d6b711887586646346d
>> change-id: 20260803-slim-disable-stream-support-43599401607f
>>
>> Best regards,
>> --  
>> Viken Dadhaniya <viken.dadhaniya@xxxxxxxxxxxxxxxx>
>>
>