user-space ll: grant access to DAIs and DMAs #10533

kv2019i · 2026-02-09T14:00:28Z

A small set of patches that allow granting access to all DAIs and DMAs to a user-space thread, and this is case, the LL scheduler threads when run in user-space. This PR uses the existing helper code in SOF that allow to enumerate the devices in a platform-agnostic manner, so this PR works for all SOF build targerts.

Add helper functions to provide a list of all Zephyr devices and to grant a user thread access to them. Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>

Add helper functions to provide a list of all Zephyr DMA devices and to grant a user thread access to them. Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>

If the low-latency domain tasks are run in user-space, grant the LL threads access to all DAI and DMA devices. In future, there may be need to filter access permissions more, and/or have variation between different build targets, but for now the user LL thread will have access to the same devices as it does in kernel space. Note that access to memory is separately controlled and in addition to having access to a DMA device, user-space thread also needs access to the memory before it can do DMA transactions. Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>

Now that we have CONFIG_SOF_USERSPACE_LL, use it to conditionally drop some of the thread access helpers. Access to mailbox, DAIs and DMAs is currently only needed if LL thread is run in user-space. Leave these out if SOF is built for LL thread scheduling in kernel space. Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>

kv2019i · 2026-02-09T14:01:33Z

Looks like this when running the "userspace_ll" ztest on a Intel PTL system:

Running TESTSUITE userspace_ll
===================================================================
START - ll_task_test
[    0.000095] <dbg> ll_schedule: zephyr_ll_task_init: ll-scheduler task 0x400de000 init
[    0.000095] <inf> sof_boot_test: ll_task_test: task init done
[    0.000095] <inf> ll_schedule: zephyr_ll_task_schedule_common: task add 0xa02422c0 0xa00d38e4U priority 0 flags 0x0
[    0.000095] <dbg> ll_schedule: zephyr_domain_register_user: entry
thread_alloc user, heap 0x400e09dc, sys-heap 0x400e09dc
thread_alloc user, heap 0x400e09dc, sys-heap 0x400e09dc
[    0.000095] <dbg> userspace_helper: user_grant_dai_access_all: Granted DAI access to thread 0x400d6640 for 45 devices
[    0.000095] <dbg> userspace_helper: user_grant_dma_access_all: Granted DMA device access: 0 dma@72c00 to thread 0x400d6640
[    0.000095] <dbg> userspace_helper: user_grant_dma_access_all: Granted DMA device access: 1 dma@72800 to thread 0x400d6640
[    0.000095] <dbg> userspace_helper: user_grant_dma_access_all: Granted DMA device access: 2 dma@79800 to thread 0x400d6640
[    0.000095] <dbg> userspace_helper: user_grant_dma_access_all: Granted DMA device access: 3 dma@79400 to thread 0x400d6640
[    0.000095] <dbg> ll_schedule: zephyr_domain_register_user: granted LL access to thread 0x400d6640 (core 0)

Copilot

Pull request overview

Adds user-space support for LL scheduler threads by granting them access to all platform DAIs and DMAs, using existing SOF device enumeration helpers.

Changes:

Add helpers to grant a user thread access to all DAI/DMA Zephyr devices
Expose DMA/DAI device list APIs for platform-agnostic enumeration
Integrate the new access grants into Zephyr LL domain thread registration

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
zephyr/lib/userspace_helper.c	Adds userspace helpers to grant access to all DAIs/DMAs and introduces logging
zephyr/lib/dma.c	Adds API to enumerate DMA Zephyr devices
zephyr/include/sof/lib/dma.h	Declares the new DMA device list API
zephyr/include/rtos/userspace_helper.h	Declares new userspace grant helper APIs
src/schedule/zephyr_domain.c	Grants DAI/DMA access to LL user threads during registration
src/lib/dai.c	Adds API to enumerate DAI Zephyr devices
src/include/sof/lib/dai-zephyr.h	Declares the new DAI device list API

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

Copilot · 2026-02-09T14:02:34Z

zephyr/lib/userspace_helper.c

+#ifdef CONFIG_SOF_USERSPACE_LL
+
 int user_access_to_mailbox(struct k_mem_domain *domain, k_tid_t thread_id)


user_access_to_mailbox() is now compiled only when CONFIG_SOF_USERSPACE_LL is enabled, but it appears to be a general userspace helper (and is still declared under #if CONFIG_USERSPACE in the header). This creates a concrete risk of link failures or missing functionality in CONFIG_USERSPACE=y builds that don’t enable CONFIG_SOF_USERSPACE_LL. Consider moving the #ifdef CONFIG_SOF_USERSPACE_LL guard so it only wraps the new DAI/DMA grant helpers (not user_access_to_mailbox()), or alternatively provide stubs / adjust header declarations so the build remains consistent across configurations.

Copilot · 2026-02-09T14:02:34Z

src/schedule/zephyr_domain.c

 		k_thread_access_grant(thread, dt->sem, domain->lock, zephyr_domain->timer);
+		user_grant_dai_access_all(thread);
+		user_grant_dma_access_all(thread);


These calls are unconditional, but the implementations in userspace_helper.c are built only under CONFIG_USERSPACE && CONFIG_SOF_USERSPACE_LL (and currently the header declarations are not similarly guarded). This can lead to unresolved symbols in configurations where this file is compiled but CONFIG_SOF_USERSPACE_LL (or even CONFIG_USERSPACE) is off. Guard these calls with the same Kconfig option(s), and/or provide static inline no-op stubs in the header for non-enabled configurations.

Suggested change

k_thread_access_grant(thread, dt->sem, domain->lock, zephyr_domain->timer);

user_grant_dai_access_all(thread);

user_grant_dma_access_all(thread);

k_thread_access_grant(thread, dt->sem, domain->lock, zephyr_domain->timer);

#if CONFIG_USERSPACE && CONFIG_SOF_USERSPACE_LL

user_grant_dai_access_all(thread);

user_grant_dma_access_all(thread);

#endif

Copilot · 2026-02-09T14:02:35Z

zephyr/include/rtos/userspace_helper.h

+ *
+ * @param thread user-space thread for which DAI access is granted
+ */
+void user_grant_dai_access_all(struct k_thread *thread);


These APIs are declared for all CONFIG_USERSPACE builds, but the implementations are under CONFIG_SOF_USERSPACE_LL in the .c file. To keep the public API consistent and avoid configuration-dependent link issues, either (1) wrap these declarations with #ifdef CONFIG_SOF_USERSPACE_LL to match the implementation, or (2) provide static inline no-op stubs when CONFIG_SOF_USERSPACE_LL is disabled.

Copilot · 2026-02-09T14:02:35Z

zephyr/include/rtos/userspace_helper.h

+ *
+ * @param thread user-space thread for which DMA access is granted
+ */
+void user_grant_dma_access_all(struct k_thread *thread);


These APIs are declared for all CONFIG_USERSPACE builds, but the implementations are under CONFIG_SOF_USERSPACE_LL in the .c file. To keep the public API consistent and avoid configuration-dependent link issues, either (1) wrap these declarations with #ifdef CONFIG_SOF_USERSPACE_LL to match the implementation, or (2) provide static inline no-op stubs when CONFIG_SOF_USERSPACE_LL is disabled.

Copilot · 2026-02-09T14:02:35Z

zephyr/include/sof/lib/dma.h

+ * \param count Pointer to store the number of devices in the list.
+ * \return Pointer to the array of device pointers.
+ */
+const struct device **dma_get_device_list(size_t *count);


Returning const struct device ** allows callers to modify the returned array contents (even if the devices themselves are const). Since this API is exposing a shared internal list, it should return an immutable list type: const struct device * const *. Same applies to dai_get_device_list() for consistency/safety.

Suggested change

const struct device **dma_get_device_list(size_t *count);

const struct device * const *dma_get_device_list(size_t *count);

Copilot · 2026-02-09T14:02:35Z

zephyr/lib/dma.c

+const struct device **dma_get_device_list(size_t *count)
+{
+	static const struct device *device_list[ARRAY_SIZE(dma)];
+	int i;


dma_get_device_list() writes to a function-static array on every call. If multiple threads can call this concurrently, this introduces a data race on device_list[]. To avoid racy writes, populate the list once during a single-threaded init phase (e.g., in dmac_init()), or implement a one-time initialization guard that does not perform concurrent writes.

Copilot · 2026-02-09T14:02:36Z

zephyr/lib/dma.c

+	int i;
+
+	if (count)
+		*count = ARRAY_SIZE(dma);
+
+	for (i = 0; i < ARRAY_SIZE(dma); i++)
+		device_list[i] = dma[i].z_dev;
+


dma_get_device_list() writes to a function-static array on every call. If multiple threads can call this concurrently, this introduces a data race on device_list[]. To avoid racy writes, populate the list once during a single-threaded init phase (e.g., in dmac_init()), or implement a one-time initialization guard that does not perform concurrent writes.

Suggested change

int i;

if (count)

*count = ARRAY_SIZE(dma);

for (i = 0; i < ARRAY_SIZE(dma); i++)

device_list[i] = dma[i].z_dev;

static struct k_spinlock device_list_lock;

static int device_list_initialized;

int i;

k_spinlock_key_t key;

if (count)

*count = ARRAY_SIZE(dma);

key = k_spin_lock(&device_list_lock);

if (!device_list_initialized) {

for (i = 0; i < ARRAY_SIZE(dma); i++)

device_list[i] = dma[i].z_dev;

device_list_initialized = 1;

}

k_spin_unlock(&device_list_lock, key);

Copilot · 2026-02-09T14:02:36Z

zephyr/lib/userspace_helper.c

+	for (i = 0; i < count; i++) {
+		k_thread_access_grant(thread, devices[i]);
+		LOG_DBG("Granted DMA device access: %d %s to thread %p",
+			i, devices[i]->name, thread);
+	}
+}
+


Logging once per DMA device can become noisy and adds overhead (even at LOG_DBG, it still does formatting work depending on Zephyr logging configuration). Consider logging a single summary line (as done for DAI) or gating per-device debug logs behind a more verbose config.

Suggested change

for (i = 0; i < count; i++) {

k_thread_access_grant(thread, devices[i]);

LOG_DBG("Granted DMA device access: %d %s to thread %p",

i, devices[i]->name, thread);

}

}

for (i = 0; i < count; i++)

k_thread_access_grant(thread, devices[i]);

LOG_DBG("Granted DMA access to thread %p for %zu devices", thread, count);

}

lgirdwood

Nothing major from me, just one question.

lgirdwood · 2026-02-09T15:57:00Z

src/lib/dai.c


+const struct device **dai_get_device_list(size_t *count)
+{
+	if (count)


Seems count is mandatory ? assert ?

kv2019i added 4 commits February 9, 2026 15:14

dai: add functionality to grant access to DAI devices

cffaeae

Add helper functions to provide a list of all Zephyr devices and to grant a user thread access to them. Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>

dma: add functionality to grant access to DMA devices

b36268a

Add helper functions to provide a list of all Zephyr DMA devices and to grant a user thread access to them. Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>

Copilot AI review requested due to automatic review settings February 9, 2026 14:00

kv2019i requested review from LaurentiuM1234, abonislawski, dbaluta, iuliana-prodan, lbetlej, lgirdwood, lyakh, marcinszkudlinski, mmaka1, pblaszko and plbossart as code owners February 9, 2026 14:00

kv2019i requested review from jsarha and softwarecki February 9, 2026 14:00

Copilot AI reviewed Feb 9, 2026

View reviewed changes

lgirdwood reviewed Feb 9, 2026

View reviewed changes

src/lib/dai.c

const struct device **dai_get_device_list(size_t *count)

{

if (count)

Copy link

Member

lgirdwood Feb 9, 2026

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Seems count is mandatory ? assert ?

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

user-space ll: grant access to DAIs and DMAs #10533

user-space ll: grant access to DAIs and DMAs #10533

kv2019i commented Feb 9, 2026

Uh oh!

kv2019i commented Feb 9, 2026

Uh oh!

Copilot AI left a comment

Uh oh!

Copilot AI Feb 9, 2026

Uh oh!

Copilot AI Feb 9, 2026

Uh oh!

Copilot AI Feb 9, 2026

Uh oh!

Copilot AI Feb 9, 2026

Uh oh!

Copilot AI Feb 9, 2026

Uh oh!

Copilot AI Feb 9, 2026

Uh oh!

Copilot AI Feb 9, 2026

Uh oh!

Copilot AI Feb 9, 2026

Uh oh!

lgirdwood left a comment

Uh oh!

lgirdwood Feb 9, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

		#ifdef CONFIG_SOF_USERSPACE_LL

		int user_access_to_mailbox(struct k_mem_domain *domain, k_tid_t thread_id)

	const struct device *dma_get_device_list(size_t count);
	const struct device * const dma_get_device_list(size_t count);

user-space ll: grant access to DAIs and DMAs #10533

Are you sure you want to change the base?

user-space ll: grant access to DAIs and DMAs #10533

Conversation

kv2019i commented Feb 9, 2026

Uh oh!

kv2019i commented Feb 9, 2026

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Reviewed changes

Uh oh!

Copilot AI Feb 9, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Feb 9, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Feb 9, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Feb 9, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Feb 9, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Feb 9, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Feb 9, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Feb 9, 2026

Choose a reason for hiding this comment

Uh oh!

lgirdwood left a comment

Choose a reason for hiding this comment

Uh oh!

lgirdwood Feb 9, 2026

Choose a reason for hiding this comment

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants