Re: [PATCH 5/6] remoteproc: qcom: pas: Add late attach support for subsystems

[Zhongqiu Han <zhongqiu.han@oss.qualcomm.com>]

On 9/25/2025 7:37 AM, Jingyi Wang wrote:
> From: Gokul krishna Krishnakumar <Gokul.krishnakumar@oss.qualcomm>
> 
> Subsystems can be brought out of reset by entities such as
> bootloaders. Before attaching such subsystems, it is important to
> check the state of the subsystem. This patch adds support to attach
> to a subsystem by ensuring that the subsystem is in a sane state by
> reading SMP2P bits and pinging the subsystem.
> 
> Signed-off-by: Gokul krishna Krishnakumar <Gokul.krishnakumar@oss.qualcomm>
> Co-developed-by: Jingyi Wang <jingyi.wang@oss.qualcomm.com>
> Signed-off-by: Jingyi Wang <jingyi.wang@oss.qualcomm.com>
> ---
>   drivers/remoteproc/qcom_q6v5.c      | 89 ++++++++++++++++++++++++++++++++++++-
>   drivers/remoteproc/qcom_q6v5.h      | 14 +++++-
>   drivers/remoteproc/qcom_q6v5_adsp.c |  2 +-
>   drivers/remoteproc/qcom_q6v5_mss.c  |  2 +-
>   drivers/remoteproc/qcom_q6v5_pas.c  | 61 ++++++++++++++++++++++++-
>   5 files changed, 163 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/remoteproc/qcom_q6v5.c b/drivers/remoteproc/qcom_q6v5.c
> index 4ee5e67a9f03..cba05e1d6d52 100644
> --- a/drivers/remoteproc/qcom_q6v5.c
> +++ b/drivers/remoteproc/qcom_q6v5.c
> @@ -94,6 +94,9 @@ static irqreturn_t q6v5_wdog_interrupt(int irq, void *data)
>   	size_t len;
>   	char *msg;
>   
> +	if (q6v5->early_boot)
> +		complete(&q6v5->subsys_booted);
> +
>   	/* Sometimes the stop triggers a watchdog rather than a stop-ack */
>   	if (!q6v5->running) {
>   		complete(&q6v5->stop_done);
> @@ -118,6 +121,9 @@ static irqreturn_t q6v5_fatal_interrupt(int irq, void *data)
>   	size_t len;
>   	char *msg;
>   
> +	if (q6v5->early_boot)
> +		complete(&q6v5->subsys_booted);
> +
>   	if (!q6v5->running)
>   		return IRQ_HANDLED;
>   
> @@ -139,6 +145,9 @@ static irqreturn_t q6v5_ready_interrupt(int irq, void *data)
>   
>   	complete(&q6v5->start_done);
>   
> +	if (q6v5->early_boot)
> +		complete(&q6v5->subsys_booted);
> +
>   	return IRQ_HANDLED;
>   }
>   
> @@ -170,6 +179,9 @@ static irqreturn_t q6v5_handover_interrupt(int irq, void *data)
>   	if (q6v5->handover)
>   		q6v5->handover(q6v5);
>   
> +	if (q6v5->early_boot)
> +		complete(&q6v5->subsys_booted);
> +
>   	icc_set_bw(q6v5->path, 0, 0);
>   
>   	q6v5->handover_issued = true;
> @@ -232,6 +244,77 @@ unsigned long qcom_q6v5_panic(struct qcom_q6v5 *q6v5)
>   }
>   EXPORT_SYMBOL_GPL(qcom_q6v5_panic);
>   
> +static irqreturn_t q6v5_pong_interrupt(int irq, void *data)
> +{
> +	struct qcom_q6v5 *q6v5 = data;
> +
> +	complete(&q6v5->ping_done);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +int qcom_q6v5_ping_subsystem(struct qcom_q6v5 *q6v5)
> +{
> +	int ret;
> +	int ping_failed = 0;
> +
> +	reinit_completion(&q6v5->ping_done);
> +
> +	/* Set master kernel Ping bit */
> +	ret = qcom_smem_state_update_bits(q6v5->ping_state,
> +					  BIT(q6v5->ping_bit), BIT(q6v5->ping_bit));
> +	if (ret) {
> +		dev_err(q6v5->dev, "Failed to update ping bits\n");
> +		return ret;
> +	}
> +
> +	ret = wait_for_completion_timeout(&q6v5->ping_done, msecs_to_jiffies(PING_TIMEOUT));
> +	if (!ret) {
> +		ping_failed = -ETIMEDOUT;
> +		dev_err(q6v5->dev, "Failed to get back pong\n");
> +	}
> +
> +	/* Clear ping bit master kernel */
> +	ret = qcom_smem_state_update_bits(q6v5->ping_state, BIT(q6v5->ping_bit), 0);
> +	if (ret) {
> +		pr_err("Failed to clear master kernel bits\n");
> +		return ret;
> +	}
> +
> +	if (ping_failed)
> +		return ping_failed;
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(qcom_q6v5_ping_subsystem);
> +
> +int qcom_q6v5_ping_subsystem_init(struct qcom_q6v5 *q6v5, struct platform_device *pdev)
> +{
> +	int ret = -ENODEV;
> +
> +	q6v5->ping_state = devm_qcom_smem_state_get(&pdev->dev, "ping", &q6v5->ping_bit);
> +	if (IS_ERR(q6v5->ping_state)) {
> +		dev_err(&pdev->dev, "failed to acquire smem state %ld\n",
> +			PTR_ERR(q6v5->ping_state));
> +		return ret;
> +	}
> +
> +	q6v5->pong_irq = platform_get_irq_byname(pdev, "pong");
> +	if (q6v5->pong_irq < 0)
> +		return q6v5->pong_irq;
> +
> +	ret = devm_request_threaded_irq(&pdev->dev, q6v5->pong_irq, NULL,
> +					q6v5_pong_interrupt, IRQF_TRIGGER_RISING | IRQF_ONESHOT,
> +					"q6v5 pong", q6v5);
> +	if (ret)
> +		dev_err(&pdev->dev, "failed to acquire pong IRQ\n");
> +
> +	init_completion(&q6v5->ping_done);

Hello Jingyi,

Since no IRQF_NO_AUTOEN flag is passed to devm_request_threaded_irq(),
the IRQ may be enabled immediately after registration.
If the thread_fn q6v5_pong_interrupt runs before
init_completion(&q6v5->ping_done) is called, it may lead to accessing an
uninitialized completion structure ?


> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(qcom_q6v5_ping_subsystem_init);
> +
>   /**
>    * qcom_q6v5_init() - initializer of the q6v5 common struct
>    * @q6v5:	handle to be initialized
> @@ -245,7 +328,7 @@ EXPORT_SYMBOL_GPL(qcom_q6v5_panic);
>    */
>   int qcom_q6v5_init(struct qcom_q6v5 *q6v5, struct platform_device *pdev,
>   		   struct rproc *rproc, int crash_reason, const char *load_state,
> -		   void (*handover)(struct qcom_q6v5 *q6v5))
> +		   bool early_boot, void (*handover)(struct qcom_q6v5 *q6v5))
>   {
>   	int ret;
>   
> @@ -253,10 +336,14 @@ int qcom_q6v5_init(struct qcom_q6v5 *q6v5, struct platform_device *pdev,
>   	q6v5->dev = &pdev->dev;
>   	q6v5->crash_reason = crash_reason;
>   	q6v5->handover = handover;
> +	q6v5->early_boot = early_boot;
>   
>   	init_completion(&q6v5->start_done);
>   	init_completion(&q6v5->stop_done);
>   
> +	if (early_boot)
> +		init_completion(&q6v5->subsys_booted);
> +
>   	q6v5->wdog_irq = platform_get_irq_byname(pdev, "wdog");
>   	if (q6v5->wdog_irq < 0)
>   		return q6v5->wdog_irq;
> diff --git a/drivers/remoteproc/qcom_q6v5.h b/drivers/remoteproc/qcom_q6v5.h
> index 5a859c41896e..8a227bf70d7e 100644
> --- a/drivers/remoteproc/qcom_q6v5.h
> +++ b/drivers/remoteproc/qcom_q6v5.h
> @@ -12,27 +12,35 @@ struct rproc;
>   struct qcom_smem_state;
>   struct qcom_sysmon;
>   
> +#define PING_TIMEOUT 500 /* in milliseconds */
> +#define PING_TEST_WAIT 500 /* in milliseconds */
> +
>   struct qcom_q6v5 {
>   	struct device *dev;
>   	struct rproc *rproc;
>   
>   	struct qcom_smem_state *state;
> +	struct qcom_smem_state *ping_state;
>   	struct qmp *qmp;
>   
>   	struct icc_path *path;
>   
>   	unsigned stop_bit;
> +	unsigned int ping_bit;
>   
>   	int wdog_irq;
>   	int fatal_irq;
>   	int ready_irq;
>   	int handover_irq;
>   	int stop_irq;
> +	int pong_irq;
>   
>   	bool handover_issued;
>   
>   	struct completion start_done;
>   	struct completion stop_done;
> +	struct completion subsys_booted;
> +	struct completion ping_done;
>   
>   	int crash_reason;
>   
> @@ -40,11 +48,13 @@ struct qcom_q6v5 {
>   
>   	const char *load_state;
>   	void (*handover)(struct qcom_q6v5 *q6v5);
> +
> +	bool early_boot;
>   };
>   
>   int qcom_q6v5_init(struct qcom_q6v5 *q6v5, struct platform_device *pdev,
>   		   struct rproc *rproc, int crash_reason, const char *load_state,
> -		   void (*handover)(struct qcom_q6v5 *q6v5));
> +		   bool early_boot, void (*handover)(struct qcom_q6v5 *q6v5));
>   void qcom_q6v5_deinit(struct qcom_q6v5 *q6v5);
>   
>   int qcom_q6v5_prepare(struct qcom_q6v5 *q6v5);
> @@ -52,5 +62,7 @@ int qcom_q6v5_unprepare(struct qcom_q6v5 *q6v5);
>   int qcom_q6v5_request_stop(struct qcom_q6v5 *q6v5, struct qcom_sysmon *sysmon);
>   int qcom_q6v5_wait_for_start(struct qcom_q6v5 *q6v5, int timeout);
>   unsigned long qcom_q6v5_panic(struct qcom_q6v5 *q6v5);
> +int qcom_q6v5_ping_subsystem(struct qcom_q6v5 *q6v5);
> +int qcom_q6v5_ping_subsystem_init(struct qcom_q6v5 *q6v5, struct platform_device *pdev);
>   
>   #endif
> diff --git a/drivers/remoteproc/qcom_q6v5_adsp.c b/drivers/remoteproc/qcom_q6v5_adsp.c
> index e98b7e03162c..1576b435b921 100644
> --- a/drivers/remoteproc/qcom_q6v5_adsp.c
> +++ b/drivers/remoteproc/qcom_q6v5_adsp.c
> @@ -717,7 +717,7 @@ static int adsp_probe(struct platform_device *pdev)
>   		goto disable_pm;
>   
>   	ret = qcom_q6v5_init(&adsp->q6v5, pdev, rproc, desc->crash_reason_smem,
> -			     desc->load_state, qcom_adsp_pil_handover);
> +			     desc->load_state, false, qcom_adsp_pil_handover);
>   	if (ret)
>   		goto disable_pm;
>   
> diff --git a/drivers/remoteproc/qcom_q6v5_mss.c b/drivers/remoteproc/qcom_q6v5_mss.c
> index 0c0199fb0e68..04e577541c8f 100644
> --- a/drivers/remoteproc/qcom_q6v5_mss.c
> +++ b/drivers/remoteproc/qcom_q6v5_mss.c
> @@ -2156,7 +2156,7 @@ static int q6v5_probe(struct platform_device *pdev)
>   	qproc->has_mba_logs = desc->has_mba_logs;
>   
>   	ret = qcom_q6v5_init(&qproc->q6v5, pdev, rproc, MPSS_CRASH_REASON_SMEM, "modem",
> -			     qcom_msa_handover);
> +			     false, qcom_msa_handover);
>   	if (ret)
>   		goto detach_proxy_pds;
>   
> diff --git a/drivers/remoteproc/qcom_q6v5_pas.c b/drivers/remoteproc/qcom_q6v5_pas.c
> index 55a7da801183..99163e48a76a 100644
> --- a/drivers/remoteproc/qcom_q6v5_pas.c
> +++ b/drivers/remoteproc/qcom_q6v5_pas.c
> @@ -35,6 +35,8 @@
>   
>   #define MAX_ASSIGN_COUNT 3
>   
> +#define EARLY_BOOT_RETRY_INTERVAL_MS 5000
> +
>   struct qcom_pas_data {
>   	int crash_reason_smem;
>   	const char *firmware_name;
> @@ -58,6 +60,7 @@ struct qcom_pas_data {
>   	int region_assign_count;
>   	bool region_assign_shared;
>   	int region_assign_vmid;
> +	bool early_boot;
>   };
>   
>   struct qcom_pas {
> @@ -430,6 +433,51 @@ static unsigned long qcom_pas_panic(struct rproc *rproc)
>   	return qcom_q6v5_panic(&pas->q6v5);
>   }
>   
> +static int qcom_pas_attach(struct rproc *rproc)
> +{
> +	int ret;
> +	struct qcom_pas *adsp = rproc->priv;
> +	bool ready_state;
> +	bool crash_state;
> +
> +	if (!adsp->q6v5.early_boot)
> +		return -EINVAL;
> +
> +	ret = irq_get_irqchip_state(adsp->q6v5.fatal_irq,
> +				    IRQCHIP_STATE_LINE_LEVEL, &crash_state);
> +
> +	if (crash_state) {
> +		dev_err(adsp->dev, "Sub system has crashed before driver probe\n");
> +		adsp->rproc->state = RPROC_CRASHED;
> +		return -EINVAL;
> +	}
> +
> +	ret = irq_get_irqchip_state(adsp->q6v5.ready_irq,
> +				    IRQCHIP_STATE_LINE_LEVEL, &ready_state);
> +
> +	if (ready_state) {
> +		dev_info(adsp->dev, "Sub system has boot-up before driver probe\n");
> +		adsp->rproc->state = RPROC_DETACHED;
> +	} else {
> +		ret = wait_for_completion_timeout(&adsp->q6v5.subsys_booted,
> +						  msecs_to_jiffies(EARLY_BOOT_RETRY_INTERVAL_MS));
> +		if (!ret) {
> +			dev_err(adsp->dev, "Timeout on waiting for subsystem interrupt\n");
> +			return -ETIMEDOUT;
> +		}
> +	}
> +
> +	ret = qcom_q6v5_ping_subsystem(&adsp->q6v5);
> +	if (ret) {
> +		dev_err(adsp->dev, "Failed to ping subsystem, assuming device crashed\n");
> +		rproc->state = RPROC_CRASHED;
> +		return ret;
> +	}
> +
> +	adsp->q6v5.running = true;
> +	return ret;
> +}
> +
>   static const struct rproc_ops qcom_pas_ops = {
>   	.unprepare = qcom_pas_unprepare,
>   	.start = qcom_pas_start,
> @@ -438,6 +486,7 @@ static const struct rproc_ops qcom_pas_ops = {
>   	.parse_fw = qcom_register_dump_segments,
>   	.load = qcom_pas_load,
>   	.panic = qcom_pas_panic,
> +	.attach = qcom_pas_attach,
>   };
>   
>   static const struct rproc_ops qcom_pas_minidump_ops = {
> @@ -760,7 +809,7 @@ static int qcom_pas_probe(struct platform_device *pdev)
>   	pas->proxy_pd_count = ret;
>   
>   	ret = qcom_q6v5_init(&pas->q6v5, pdev, rproc, desc->crash_reason_smem,
> -			     desc->load_state, qcom_pas_handover);
> +			     desc->load_state, desc->early_boot, qcom_pas_handover);
>   	if (ret)
>   		goto detach_proxy_pds;
>   
> @@ -774,6 +823,16 @@ static int qcom_pas_probe(struct platform_device *pdev)
>   	}
>   
>   	qcom_add_ssr_subdev(rproc, &pas->ssr_subdev, desc->ssr_name);
> +
> +	if (pas->q6v5.early_boot) {
> +		ret = qcom_q6v5_ping_subsystem_init(&pas->q6v5, pdev);
> +		if (ret)
> +			dev_err(&pdev->dev,
> +				"Unable to find ping/pong bits, falling back to firmware load\n");
> +		else
> +			pas->rproc->state = RPROC_DETACHED;
> +	}
> +
>   	ret = rproc_add(rproc);
>   	if (ret)
>   		goto remove_ssr_sysmon;
> 


-- 
Thx and BRs,
Zhongqiu Han