[PATCH v8 0/3] SCM: Support latest version of waitq-aware firmware

[PATCH v8 0/3] SCM: Support latest version of waitq-aware firmware

[Shivendra Pratap]

This series adds support for the latest improvements made in SCM
firmware that allow for multiple wait-queues in firmware.

To support multi VM synchronization when VMs make SMC calls on same CPU,
waitqueue mechanism is added in firmware which runs at EL2 & EL3 exception
levels.

Thanks to Unnathi for bringing the path to this level of maturity.
P.S. While at Qualcomm, Guru Das Srinagesh authored the initial version of
these patches.
Thanks Guru!

Signed-off-by: Unnathi Chalicheemala <unnathi.chalicheemala@oss.qualcomm.com>
Signed-off-by: Shivendra Pratap <shivendra.pratap@oss.qualcomm.com>

---
Changes in v8:
- Replace "of_node_to_fwnode" with "of_fwnode_handle to align
  with current kernel version.
- Add NULL check for parent_irq_node in function qcom_scm_get_waitq_irq. 
- Change declaration of qcom_scm_get_waitq_irq and pass qcom_scm pointer.
- Set the scm->wq_cnt to one, in case where waitqueue is not
  supported by firmware and continue to probe the qcom_scm driver.
- Link to v7: https://lore.kernel.org/all/20250523-multi_waitq_scm-v7-0-5b51b60ed396@oss.qualcomm.com/

Changes in v7:
- Assume failing scm call to mean WAITQ_GET_INFO is not supported on target
  as qcom_scm_is_call_available() is handled in Qualcomm firmware's TZ (EL3),
  which doesn’t implement WAITQ_GET_INFO, and therefore always returns 0.
- Link to v6: https://lore.kernel.org/r/20250425-multi_waitq_scm-v6-0-cba8ca5a6d03@oss.qualcomm.com

Changes in v6:
- Added R-b tag from Bartosz for first patch.
- Check if QCOM_SCM_WAITQ_GET_INFO is available before making scm call,
instead of assuming failing scm call to mean WAITQ_GET_INFO is not
supported on target.
- Add a new patch to check for waitq idle state in wait_for_wq_completion().
- Link to v5: https://lore.kernel.org/all/20250227-multi_waitq_scm-v5-0-16984ea97edf@oss.qualcomm.com/

Changes in v5:
- Use GIC_SPI and GIC_ESPI macros from dt-bindings instead of redefining
- Modified qcom_scm_query_waitq_count to take struct qcom_scm as
argument; scm is anyway stored to global struct __scm after
smp_store_and_release().
- Tested on SM8650 which has multi-waitq support and SM8550, which
doesn't. No error logs are seen.
-Link to v4: https://lore.kernel.org/all/cover.1730742637.git.quic_uchalich@quicinc.com/

Changes in v4:
- Moving back to redefining GIC_IRQ_TYPE_SPI and GIC_IRQ_TYPE_ESPI macros
in qcom_scm as seeing compilation issues in linux/irq.h when including
arm-gic header. Will send a fixes patch and move to dt-bindings in next patchset.
- Fixed a few compilation errors.
- Link to v3: https://lore.kernel.org/all/cover.1730735881.git.quic_uchalich@quicinc.com/

Changes in v3:
- Use GIC_SPI and GIC_ESPI macros from dt-bindings instead of redefining
- Prettified qcom_scm_fill_irq_fwspec_params()
- Moved waitq initialization before smp_store_release()
- There is no Gunyah hypercall API that can be used to fetch IRQ information hence
introducing new SCM call.
- Link to v2: https://lore.kernel.org/all/cover.1724968351.git.quic_uchalich@quicinc.com/

Changes in v2:
- Dropped "Initialize waitq before setting global __scm" as it was merged here:
https://lore.kernel.org/r/1711034642-22860-4-git-send-email-quic_mojha@quicinc.com
- Decoupled "Remove QCOM_SMC_WAITQ_FLAG_WAKE_ALL" from series
- Converted xarray to a statically sized array
- Initialize waitq array in probe function
- Remove reinit of waitq completion struct in scm_get_completion()
- Introduced new APIs to get no. of waitqueue contexts and waitqueue IRQ no.
directly from firmware.
- Link to v1: https://lore.kernel.org/all/20240228-multi_waitq-v1-0-ccb096419af0@quicinc.com/

---
Unnathi Chalicheemala (3):
      firmware: qcom_scm: Add API to get waitqueue IRQ info
      firmware: qcom_scm: Support multiple waitq contexts
      firmware: qcom_scm: Check for waitq state in wait_for_wq_completion()

 drivers/firmware/qcom/qcom_scm.c | 129 +++++++++++++++++++++++++++++++++------
 drivers/firmware/qcom/qcom_scm.h |   1 +
 2 files changed, 111 insertions(+), 19 deletions(-)
---
base-commit: f9ba12abc5282bf992f9a9ae87ad814fd03a0270
change-id: 20250227-multi_waitq_scm-5bf05480b7b1

Best regards,
-- 
Shivendra Pratap <shivendra.pratap@oss.qualcomm.com>

[PATCH v8 1/3] firmware: qcom_scm: Add API to get waitqueue IRQ info

[Shivendra Pratap]

From: Unnathi Chalicheemala <unnathi.chalicheemala@oss.qualcomm.com>

Bootloader and firmware for SM8650 and older chipsets expect node
name as "qcom_scm", in order to patch the wait queue IRQ information.
However, DeviceTree uses node name "scm" and this mismatch prevents
firmware from correctly identifying waitqueue IRQ information. Waitqueue
IRQ is used for signaling between secure and non-secure worlds.

To resolve this, introduce qcom_scm_get_waitq_irq() that'll get the
hardware IRQ number to be used from firmware instead of relying on data
provided by devicetree, thereby bypassing the DeviceTree node name
mismatch.

This hardware IRQ number is converted to a Linux IRQ number using newly
defined fill_irq_fwspec_params(). This Linux IRQ number is then supplied
to the threaded_irq call.

Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Signed-off-by: Unnathi Chalicheemala <unnathi.chalicheemala@oss.qualcomm.com>
Signed-off-by: Shivendra Pratap <shivendra.pratap@oss.qualcomm.com>
---
 drivers/firmware/qcom/qcom_scm.c | 62 +++++++++++++++++++++++++++++++++++++++-
 drivers/firmware/qcom/qcom_scm.h |  1 +
 2 files changed, 62 insertions(+), 1 deletion(-)

diff --git a/drivers/firmware/qcom/qcom_scm.c b/drivers/firmware/qcom/qcom_scm.c
index e777b7cb9b127944fe112f453cae9cbc40c06cae..28979f95e51fbee94b84c1570a4d88a76f72db4e 100644
--- a/drivers/firmware/qcom/qcom_scm.c
+++ b/drivers/firmware/qcom/qcom_scm.c
@@ -29,12 +29,18 @@
 #include <linux/reset-controller.h>
 #include <linux/sizes.h>
 #include <linux/types.h>
+#include <dt-bindings/interrupt-controller/arm-gic.h>
 
 #include "qcom_scm.h"
 #include "qcom_tzmem.h"
 
 static u32 download_mode;
 
+#define GIC_SPI_BASE        32
+#define GIC_MAX_SPI       1019  // SPIs in GICv3 spec range from 32..1019
+#define GIC_ESPI_BASE     4096
+#define GIC_MAX_ESPI      5119 // ESPIs in GICv3 spec range from 4096..5119
+
 struct qcom_scm {
 	struct device *dev;
 	struct clk *core_clk;
@@ -2223,6 +2229,57 @@ bool qcom_scm_is_available(void)
 }
 EXPORT_SYMBOL_GPL(qcom_scm_is_available);
 
+static int qcom_scm_fill_irq_fwspec_params(struct irq_fwspec *fwspec, u32 virq)
+{
+	if (virq >= GIC_SPI_BASE && virq <= GIC_MAX_SPI) {
+		fwspec->param[0] = GIC_SPI;
+		fwspec->param[1] = virq - GIC_SPI_BASE;
+	} else if (virq >= GIC_ESPI_BASE && virq <= GIC_MAX_ESPI) {
+		fwspec->param[0] = GIC_ESPI;
+		fwspec->param[1] = virq - GIC_ESPI_BASE;
+	} else {
+		WARN(1, "Unexpected virq: %d\n", virq);
+		return -ENXIO;
+	}
+	fwspec->param[2] = IRQ_TYPE_EDGE_RISING;
+	fwspec->param_count = 3;
+
+	return 0;
+}
+
+static int qcom_scm_get_waitq_irq(struct qcom_scm *scm)
+{
+	int ret;
+	u32 hwirq;
+	struct qcom_scm_desc desc = {
+		.svc = QCOM_SCM_SVC_WAITQ,
+		.cmd = QCOM_SCM_WAITQ_GET_INFO,
+		.owner = ARM_SMCCC_OWNER_SIP
+	};
+	struct qcom_scm_res res;
+	struct irq_fwspec fwspec;
+	struct device_node *parent_irq_node;
+
+	ret = qcom_scm_call_atomic(scm->dev, &desc, &res);
+	if (ret)
+		return ret;
+
+	hwirq = res.result[1] & GENMASK(15, 0);
+
+	ret = qcom_scm_fill_irq_fwspec_params(&fwspec, hwirq);
+	if (ret)
+		return ret;
+	parent_irq_node = of_irq_find_parent(scm->dev->of_node);
+	if (!parent_irq_node)
+		return -ENODEV;
+
+	fwspec.fwnode = of_fwnode_handle(parent_irq_node);
+
+	ret = irq_create_fwspec_mapping(&fwspec);
+
+	return ret;
+}
+
 static int qcom_scm_assert_valid_wq_ctx(u32 wq_ctx)
 {
 	/* FW currently only supports a single wq_ctx (zero).
@@ -2396,7 +2453,10 @@ static int qcom_scm_probe(struct platform_device *pdev)
 		return dev_err_probe(scm->dev, PTR_ERR(scm->mempool),
 				     "Failed to create the SCM memory pool\n");
 
-	irq = platform_get_irq_optional(pdev, 0);
+	irq = qcom_scm_get_waitq_irq(scm);
+	if (irq < 0)
+		irq = platform_get_irq_optional(pdev, 0);
+
 	if (irq < 0) {
 		if (irq != -ENXIO)
 			return irq;
diff --git a/drivers/firmware/qcom/qcom_scm.h b/drivers/firmware/qcom/qcom_scm.h
index a56c8212cc0c41021e5a067d52b7d5dcc49107ea..8b1e2ea18a59ac143907a381b73236148bace189 100644
--- a/drivers/firmware/qcom/qcom_scm.h
+++ b/drivers/firmware/qcom/qcom_scm.h
@@ -152,6 +152,7 @@ int qcom_scm_shm_bridge_enable(struct device *scm_dev);
 #define QCOM_SCM_SVC_WAITQ			0x24
 #define QCOM_SCM_WAITQ_RESUME			0x02
 #define QCOM_SCM_WAITQ_GET_WQ_CTX		0x03
+#define QCOM_SCM_WAITQ_GET_INFO		0x04
 
 #define QCOM_SCM_SVC_GPU			0x28
 #define QCOM_SCM_SVC_GPU_INIT_REGS		0x01

-- 
2.34.1

[PATCH v8 2/3] firmware: qcom_scm: Support multiple waitq contexts

[Shivendra Pratap]

From: Unnathi Chalicheemala <unnathi.chalicheemala@oss.qualcomm.com>

Currently, only a single waitqueue context exists in the driver.
Multi-waitqueue mechanism is added in firmware to support the case,
when multiple VMs make SMC calls or single VM making multiple calls on
same CPU. Enhance the driver to support multiple waitqueue when
support is present in the firmware.

When VMs make a SMC call, firmware allocates a waitqueue context,
assuming the SMC call to be a blocking call. The SMC calls that cannot
acquire resources, while execution in firmware, are returned to sleep
in the calling VM. When the resource becomes available in the
firmware, the VM gets notified to wake the sleeping thread and resume
SMC call. The current qcom_scm driver supports single waitqueue as the
old firmwares support only single waitqueue with waitqueue id zero.
Multi-waitqueue mechanism is added in firmware starting SM8650 to
support the case when multiple VMs make SMC calls or single VM making
multiple calls on same CPU. To enable this support in qcom_scm driver,
add support for handling multiple waitqueues. For instance, SM8650
firmware can allocate two such waitq contexts, so the driver needs to
implement two waitqueue contexts. For a generalized approach, the
number of supported waitqueues can be queried from the firmware using
a SMC call.

Introduce qcom_scm_query_waitq_count to get the number of waitqueue
contexts supported by the firmware and allocate “N” unique waitqueue
contexts with a dynamic sized array where each unique wq_ctx is
associated with a struct completion variable for easy lookup. Older
targets which support only a single waitqueue, may return an error for
qcom_scm_query_waitq_count, set the wq_cnt to one for such failures.

Signed-off-by: Unnathi Chalicheemala <unnathi.chalicheemala@oss.qualcomm.com>
Signed-off-by: Shivendra Pratap <shivendra.pratap@oss.qualcomm.com>
---
 drivers/firmware/qcom/qcom_scm.c | 75 ++++++++++++++++++++++++++++------------
 1 file changed, 53 insertions(+), 22 deletions(-)

diff --git a/drivers/firmware/qcom/qcom_scm.c b/drivers/firmware/qcom/qcom_scm.c
index 28979f95e51fbee94b84c1570a4d88a76f72db4e..0b6efa7c2bdc25a3ba152c25d5451d1154779ddd 100644
--- a/drivers/firmware/qcom/qcom_scm.c
+++ b/drivers/firmware/qcom/qcom_scm.c
@@ -47,7 +47,7 @@ struct qcom_scm {
 	struct clk *iface_clk;
 	struct clk *bus_clk;
 	struct icc_path *path;
-	struct completion waitq_comp;
+	struct completion *waitq;
 	struct reset_controller_dev reset;
 
 	/* control access to the interconnect path */
@@ -57,6 +57,7 @@ struct qcom_scm {
 	u64 dload_mode_addr;
 
 	struct qcom_tzmem_pool *mempool;
+	unsigned int wq_cnt;
 };
 
 struct qcom_scm_current_perm_info {
@@ -2247,6 +2248,25 @@ static int qcom_scm_fill_irq_fwspec_params(struct irq_fwspec *fwspec, u32 virq)
 	return 0;
 }
 
+static int qcom_scm_query_waitq_count(struct qcom_scm *scm)
+{
+	int ret;
+	struct qcom_scm_desc desc = {
+		.svc = QCOM_SCM_SVC_WAITQ,
+		.cmd = QCOM_SCM_WAITQ_GET_INFO,
+		.owner = ARM_SMCCC_OWNER_SIP
+	};
+	struct qcom_scm_res res;
+
+	ret = qcom_scm_call_atomic(scm->dev, &desc, &res);
+	if (ret) {
+		dev_info(scm->dev, "Multi-waitqueue support unavailable\n");
+		return ret;
+	}
+
+	return res.result[0] & GENMASK(7, 0);
+}
+
 static int qcom_scm_get_waitq_irq(struct qcom_scm *scm)
 {
 	int ret;
@@ -2280,42 +2300,40 @@ static int qcom_scm_get_waitq_irq(struct qcom_scm *scm)
 	return ret;
 }
 
-static int qcom_scm_assert_valid_wq_ctx(u32 wq_ctx)
+static struct completion *qcom_scm_get_completion(u32 wq_ctx)
 {
-	/* FW currently only supports a single wq_ctx (zero).
-	 * TODO: Update this logic to include dynamic allocation and lookup of
-	 * completion structs when FW supports more wq_ctx values.
-	 */
-	if (wq_ctx != 0) {
-		dev_err(__scm->dev, "Firmware unexpectedly passed non-zero wq_ctx\n");
-		return -EINVAL;
-	}
+	struct completion *wq;
 
-	return 0;
+	if (WARN_ON_ONCE(wq_ctx >= __scm->wq_cnt))
+		return ERR_PTR(-EINVAL);
+
+	wq = &__scm->waitq[wq_ctx];
+
+	return wq;
 }
 
 int qcom_scm_wait_for_wq_completion(u32 wq_ctx)
 {
-	int ret;
+	struct completion *wq;
 
-	ret = qcom_scm_assert_valid_wq_ctx(wq_ctx);
-	if (ret)
-		return ret;
+	wq = qcom_scm_get_completion(wq_ctx);
+	if (IS_ERR(wq))
+		return PTR_ERR(wq);
 
-	wait_for_completion(&__scm->waitq_comp);
+	wait_for_completion(wq);
 
 	return 0;
 }
 
 static int qcom_scm_waitq_wakeup(unsigned int wq_ctx)
 {
-	int ret;
+	struct completion *wq;
 
-	ret = qcom_scm_assert_valid_wq_ctx(wq_ctx);
-	if (ret)
-		return ret;
+	wq = qcom_scm_get_completion(wq_ctx);
+	if (IS_ERR(wq))
+		return PTR_ERR(wq);
 
-	complete(&__scm->waitq_comp);
+	complete(wq);
 
 	return 0;
 }
@@ -2391,6 +2409,7 @@ static int qcom_scm_probe(struct platform_device *pdev)
 	struct qcom_tzmem_pool_config pool_config;
 	struct qcom_scm *scm;
 	int irq, ret;
+	int i;
 
 	scm = devm_kzalloc(&pdev->dev, sizeof(*scm), GFP_KERNEL);
 	if (!scm)
@@ -2401,7 +2420,19 @@ static int qcom_scm_probe(struct platform_device *pdev)
 	if (ret < 0)
 		return ret;
 
-	init_completion(&scm->waitq_comp);
+	ret = qcom_scm_query_waitq_count(scm);
+	if (ret <= 0)
+		scm->wq_cnt = 1;
+	else
+		scm->wq_cnt = ret;
+
+	scm->waitq = devm_kcalloc(&pdev->dev, scm->wq_cnt, sizeof(*scm->waitq), GFP_KERNEL);
+	if (!scm->waitq)
+		return -ENOMEM;
+
+	for (i = 0; i < scm->wq_cnt; i++)
+		init_completion(&scm->waitq[i]);
+
 	mutex_init(&scm->scm_bw_lock);
 
 	scm->path = devm_of_icc_get(&pdev->dev, NULL);

-- 
2.34.1

[PATCH v8 3/3] firmware: qcom_scm: Check for waitq state in wait_for_wq_completion()

[Shivendra Pratap]

From: Unnathi Chalicheemala <unnathi.chalicheemala@oss.qualcomm.com>

Modify wait_for_wq_completion() to check if task is in idle state using
wait_for_completion_state().

This allows for detecting when waitq contexts are in idle state and
propagates it to __scm_smc_do(), which is beneficial when task is idle
and waiting for a kick to accept new requests.

Signed-off-by: Unnathi Chalicheemala <unnathi.chalicheemala@oss.qualcomm.com>
Signed-off-by: Shivendra Pratap <shivendra.pratap@oss.qualcomm.com>
---
 drivers/firmware/qcom/qcom_scm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/firmware/qcom/qcom_scm.c b/drivers/firmware/qcom/qcom_scm.c
index 0b6efa7c2bdc25a3ba152c25d5451d1154779ddd..38c1c8aff9fa3a90eca9dba700611dd12c4d82a5 100644
--- a/drivers/firmware/qcom/qcom_scm.c
+++ b/drivers/firmware/qcom/qcom_scm.c
@@ -2320,7 +2320,7 @@ int qcom_scm_wait_for_wq_completion(u32 wq_ctx)
 	if (IS_ERR(wq))
 		return PTR_ERR(wq);
 
-	wait_for_completion(wq);
+	wait_for_completion_state(wq, TASK_IDLE);
 
 	return 0;
 }

-- 
2.34.1

Re: [PATCH v8 2/3] firmware: qcom_scm: Support multiple waitq contexts

[Bartosz Golaszewski]

On Sun, Nov 2, 2025 at 9:19 AM Shivendra Pratap
<shivendra.pratap@oss.qualcomm.com> wrote:
>
> From: Unnathi Chalicheemala <unnathi.chalicheemala@oss.qualcomm.com>
>
> Currently, only a single waitqueue context exists in the driver.
> Multi-waitqueue mechanism is added in firmware to support the case,
> when multiple VMs make SMC calls or single VM making multiple calls on
> same CPU. Enhance the driver to support multiple waitqueue when
> support is present in the firmware.
>
> When VMs make a SMC call, firmware allocates a waitqueue context,
> assuming the SMC call to be a blocking call. The SMC calls that cannot
> acquire resources, while execution in firmware, are returned to sleep
> in the calling VM. When the resource becomes available in the
> firmware, the VM gets notified to wake the sleeping thread and resume
> SMC call. The current qcom_scm driver supports single waitqueue as the
> old firmwares support only single waitqueue with waitqueue id zero.
> Multi-waitqueue mechanism is added in firmware starting SM8650 to
> support the case when multiple VMs make SMC calls or single VM making
> multiple calls on same CPU. To enable this support in qcom_scm driver,
> add support for handling multiple waitqueues. For instance, SM8650
> firmware can allocate two such waitq contexts, so the driver needs to
> implement two waitqueue contexts. For a generalized approach, the
> number of supported waitqueues can be queried from the firmware using
> a SMC call.
>
> Introduce qcom_scm_query_waitq_count to get the number of waitqueue
> contexts supported by the firmware and allocate “N” unique waitqueue
> contexts with a dynamic sized array where each unique wq_ctx is
> associated with a struct completion variable for easy lookup. Older
> targets which support only a single waitqueue, may return an error for
> qcom_scm_query_waitq_count, set the wq_cnt to one for such failures.
>
> Signed-off-by: Unnathi Chalicheemala <unnathi.chalicheemala@oss.qualcomm.com>
> Signed-off-by: Shivendra Pratap <shivendra.pratap@oss.qualcomm.com>
> ---
>  drivers/firmware/qcom/qcom_scm.c | 75 ++++++++++++++++++++++++++++------------
>  1 file changed, 53 insertions(+), 22 deletions(-)
>
> diff --git a/drivers/firmware/qcom/qcom_scm.c b/drivers/firmware/qcom/qcom_scm.c
> index 28979f95e51fbee94b84c1570a4d88a76f72db4e..0b6efa7c2bdc25a3ba152c25d5451d1154779ddd 100644
> --- a/drivers/firmware/qcom/qcom_scm.c
> +++ b/drivers/firmware/qcom/qcom_scm.c
> @@ -47,7 +47,7 @@ struct qcom_scm {
>         struct clk *iface_clk;
>         struct clk *bus_clk;
>         struct icc_path *path;
> -       struct completion waitq_comp;
> +       struct completion *waitq;

Why this change? This makes the name less descriptive if not misleading.

Bartosz

Re: [PATCH v8 3/3] firmware: qcom_scm: Check for waitq state in wait_for_wq_completion()

[Bartosz Golaszewski]

On Sun, Nov 2, 2025 at 9:19 AM Shivendra Pratap
<shivendra.pratap@oss.qualcomm.com> wrote:
>
> From: Unnathi Chalicheemala <unnathi.chalicheemala@oss.qualcomm.com>
>
> Modify wait_for_wq_completion() to check if task is in idle state using
> wait_for_completion_state().
>

This is not what's happening. wait_for_completion_state(comp,
TASK_IDLE) puts the waiting task into TASK_IDLE state. It's not
checking anything.

> This allows for detecting when waitq contexts are in idle state and
> propagates it to __scm_smc_do(), which is beneficial when task is idle
> and waiting for a kick to accept new requests.
>

Could you elaborate on what benefit exactly this is giving us? It's
not quite clear from this paragraph.

Bart

Re: [PATCH v8 2/3] firmware: qcom_scm: Support multiple waitq contexts

[Shivendra Pratap]

On 11/3/2025 9:16 PM, Bartosz Golaszewski wrote:
> On Sun, Nov 2, 2025 at 9:19 AM Shivendra Pratap
> <shivendra.pratap@oss.qualcomm.com> wrote:
>>
>> From: Unnathi Chalicheemala <unnathi.chalicheemala@oss.qualcomm.com>
>>
>> Currently, only a single waitqueue context exists in the driver.
>> Multi-waitqueue mechanism is added in firmware to support the case,
>> when multiple VMs make SMC calls or single VM making multiple calls on
>> same CPU. Enhance the driver to support multiple waitqueue when
>> support is present in the firmware.
>>
>> When VMs make a SMC call, firmware allocates a waitqueue context,
>> assuming the SMC call to be a blocking call. The SMC calls that cannot
>> acquire resources, while execution in firmware, are returned to sleep
>> in the calling VM. When the resource becomes available in the
>> firmware, the VM gets notified to wake the sleeping thread and resume
>> SMC call. The current qcom_scm driver supports single waitqueue as the
>> old firmwares support only single waitqueue with waitqueue id zero.
>> Multi-waitqueue mechanism is added in firmware starting SM8650 to
>> support the case when multiple VMs make SMC calls or single VM making
>> multiple calls on same CPU. To enable this support in qcom_scm driver,
>> add support for handling multiple waitqueues. For instance, SM8650
>> firmware can allocate two such waitq contexts, so the driver needs to
>> implement two waitqueue contexts. For a generalized approach, the
>> number of supported waitqueues can be queried from the firmware using
>> a SMC call.
>>
>> Introduce qcom_scm_query_waitq_count to get the number of waitqueue
>> contexts supported by the firmware and allocate “N” unique waitqueue
>> contexts with a dynamic sized array where each unique wq_ctx is
>> associated with a struct completion variable for easy lookup. Older
>> targets which support only a single waitqueue, may return an error for
>> qcom_scm_query_waitq_count, set the wq_cnt to one for such failures.
>>
>> Signed-off-by: Unnathi Chalicheemala <unnathi.chalicheemala@oss.qualcomm.com>
>> Signed-off-by: Shivendra Pratap <shivendra.pratap@oss.qualcomm.com>
>> ---
>>  drivers/firmware/qcom/qcom_scm.c | 75 ++++++++++++++++++++++++++++------------
>>  1 file changed, 53 insertions(+), 22 deletions(-)
>>
>> diff --git a/drivers/firmware/qcom/qcom_scm.c b/drivers/firmware/qcom/qcom_scm.c
>> index 28979f95e51fbee94b84c1570a4d88a76f72db4e..0b6efa7c2bdc25a3ba152c25d5451d1154779ddd 100644
>> --- a/drivers/firmware/qcom/qcom_scm.c
>> +++ b/drivers/firmware/qcom/qcom_scm.c
>> @@ -47,7 +47,7 @@ struct qcom_scm {
>>         struct clk *iface_clk;
>>         struct clk *bus_clk;
>>         struct icc_path *path;
>> -       struct completion waitq_comp;
>> +       struct completion *waitq;
> 
> Why this change? This makes the name less descriptive if not misleading.

Want to make it dynamic array of waitq`s. Should the name be kept as 
struct completion *waitq_comp; ?

thanks,
Shivendra

Re: [PATCH v8 2/3] firmware: qcom_scm: Support multiple waitq contexts

[Bartosz Golaszewski]

On Mon, Nov 3, 2025 at 5:16 PM Shivendra Pratap
<shivendra.pratap@oss.qualcomm.com> wrote:
>
> >> diff --git a/drivers/firmware/qcom/qcom_scm.c b/drivers/firmware/qcom/qcom_scm.c
> >> index 28979f95e51fbee94b84c1570a4d88a76f72db4e..0b6efa7c2bdc25a3ba152c25d5451d1154779ddd 100644
> >> --- a/drivers/firmware/qcom/qcom_scm.c
> >> +++ b/drivers/firmware/qcom/qcom_scm.c
> >> @@ -47,7 +47,7 @@ struct qcom_scm {
> >>         struct clk *iface_clk;
> >>         struct clk *bus_clk;
> >>         struct icc_path *path;
> >> -       struct completion waitq_comp;
> >> +       struct completion *waitq;
> >
> > Why this change? This makes the name less descriptive if not misleading.
>
> Want to make it dynamic array of waitq`s. Should the name be kept as
> struct completion *waitq_comp; ?
>

Yeah, can me waitq_comps if it's plural.

Bart

Re: [PATCH v8 2/3] firmware: qcom_scm: Support multiple waitq contexts

[Shivendra Pratap]

On 11/3/2025 10:29 PM, Bartosz Golaszewski wrote:
> On Mon, Nov 3, 2025 at 5:16 PM Shivendra Pratap
> <shivendra.pratap@oss.qualcomm.com> wrote:
>>
>>>> diff --git a/drivers/firmware/qcom/qcom_scm.c b/drivers/firmware/qcom/qcom_scm.c
>>>> index 28979f95e51fbee94b84c1570a4d88a76f72db4e..0b6efa7c2bdc25a3ba152c25d5451d1154779ddd 100644
>>>> --- a/drivers/firmware/qcom/qcom_scm.c
>>>> +++ b/drivers/firmware/qcom/qcom_scm.c
>>>> @@ -47,7 +47,7 @@ struct qcom_scm {
>>>>         struct clk *iface_clk;
>>>>         struct clk *bus_clk;
>>>>         struct icc_path *path;
>>>> -       struct completion waitq_comp;
>>>> +       struct completion *waitq;
>>>
>>> Why this change? This makes the name less descriptive if not misleading.
>>
>> Want to make it dynamic array of waitq`s. Should the name be kept as
>> struct completion *waitq_comp; ?
>>
> 
> Yeah, can me waitq_comps if it's plural.
> 

Ack, Will change the name to struct completion *waitq_comps;.

thanks,
Shivendra

Re: [PATCH v8 3/3] firmware: qcom_scm: Check for waitq state in wait_for_wq_completion()

[Shivendra Pratap]

On 11/3/2025 9:21 PM, Bartosz Golaszewski wrote:
> On Sun, Nov 2, 2025 at 9:19 AM Shivendra Pratap
> <shivendra.pratap@oss.qualcomm.com> wrote:
>>
>> From: Unnathi Chalicheemala <unnathi.chalicheemala@oss.qualcomm.com>
>>
>> Modify wait_for_wq_completion() to check if task is in idle state using
>> wait_for_completion_state().
>>
> 
> This is not what's happening. wait_for_completion_state(comp,
> TASK_IDLE) puts the waiting task into TASK_IDLE state. It's not
> checking anything.

sure. Will update the commit message.

> 
>> This allows for detecting when waitq contexts are in idle state and
>> propagates it to __scm_smc_do(), which is beneficial when task is idle
>> and waiting for a kick to accept new requests.
>>
> 
> Could you elaborate on what benefit exactly this is giving us? It's
> not quite clear from this paragraph.

The TASK_IDLE state is introduced to handle scenarios where the kernel makes
a Secure Monitor Call and the firmware requests the kernel to wait.
During this wait, the thread typically enters an uninterruptible (D) state. 
If the firmware’s requested wait is long, and a device suspend request occurs
during that time, the suspend cannot proceed because the task is stuck in the
D state. To avoid blocking device suspend during these extended waits, the patch
adds support for TASK_IDLE state. This allows the thread to wait without the
device suspend.
Will update the commit message.

thanks,
Shivendra