[Linaro-mm-sig] Re: [PATCH 07/15] accel/qda: Add memory manager for CB devices

On 20-05-2026 19:56, Dmitry Baryshkov wrote:

On Tue, May 19, 2026 at 11:45:57AM +0530, Ekansh Gupta via B4 Relay wrote:

...

From: Ekansh Gupta ekansh.gupta@oss.qualcomm.com

Introduce the QDA memory manager (qda_memory_manager) to track and manage the IOMMU devices that back each compute context bank (CB).

Each CB device registered on the qda-compute-cb bus is assigned a unique ID via an XArray and wrapped in a qda_iommu_device descriptor

Why do you need an XArray? The number of devices is (more or less) fixed. You can use a normal array, allocated in the probe function after counting OF children nodes.

Normal array should be fine here, I'll check and remove this.>

...

that records the device pointer and its stream ID. This registry allows the driver to look up the correct IOMMU domain for a given session when mapping DSP buffers.

The memory manager is initialised in qda_init_device() before CB devices are populated and torn down in qda_deinit_device() after they are destroyed, ensuring no dangling references remain in the XArray.

qda_cb.c is extended with qda_cb_setup_device(), which is called immediately after a CB device is registered on the bus. It allocates a qda_iommu_device, registers it with the memory manager, and stores it as the CB device's driver data so that qda_destroy_cb_device() can retrieve and unregister it during teardown.

Assisted-by: Claude:claude-4-6-sonnet Signed-off-by: Ekansh Gupta ekansh.gupta@oss.qualcomm.com

---

drivers/accel/qda/Makefile | 1 + drivers/accel/qda/qda_cb.c | 47 ++++++++++++++ drivers/accel/qda/qda_drv.c | 34 ++++++++++ drivers/accel/qda/qda_drv.h | 5 ++ drivers/accel/qda/qda_memory_manager.c | 111 +++++++++++++++++++++++++++++++++ drivers/accel/qda/qda_memory_manager.h | 49 +++++++++++++++ drivers/accel/qda/qda_rpmsg.c | 7 +++ 7 files changed, 254 insertions(+)

diff --git a/drivers/accel/qda/Makefile b/drivers/accel/qda/Makefile index 143c9e4e789e..701fad5ffb50 100644 --- a/drivers/accel/qda/Makefile +++ b/drivers/accel/qda/Makefile @@ -8,6 +8,7 @@ obj-$(CONFIG_DRM_ACCEL_QDA) := qda.o qda-y := \ qda_cb.o \ qda_drv.o \

• qda_memory_manager.o \ qda_rpmsg.o

obj-$(CONFIG_DRM_ACCEL_QDA_COMPUTE_BUS) += qda_compute_bus.o diff --git a/drivers/accel/qda/qda_cb.c b/drivers/accel/qda/qda_cb.c index 77caf8438c67..6d540bb0ec7b 100644 --- a/drivers/accel/qda/qda_cb.c +++ b/drivers/accel/qda/qda_cb.c @@ -8,11 +8,42 @@ #include <linux/slab.h> #include <drm/drm_print.h> #include "qda_drv.h" +#include "qda_memory_manager.h" #include "qda_cb.h" +static int qda_cb_setup_device(struct qda_dev *qdev, struct device *cb_dev, u32 sid) +{

• struct qda_iommu_device *iommu_dev;
• int rc;
• drm_dbg_driver(&qdev->drm_dev, "Setting up CB device %s\n", dev_name(cb_dev));
• iommu_dev = kzalloc_obj(*iommu_dev);
• if (!iommu_dev)

• return -ENOMEM;
  

• iommu_dev->dev = cb_dev;
• iommu_dev->qdev = qdev;
• iommu_dev->sid = sid;
• rc = qda_memory_manager_register_device(qdev->iommu_mgr, iommu_dev);
• if (rc) {

• drm_err(&qdev->drm_dev, "Failed to register IOMMU device: %d\n", rc);
  

• kfree(iommu_dev);
  

• return rc;
  

• }
• dev_set_drvdata(cb_dev, iommu_dev);
• drm_dbg_driver(&qdev->drm_dev, "CB device setup complete - SID: %u\n", sid);
• return 0;

+}

int qda_create_cb_device(struct qda_dev *qdev, struct device_node *cb_node) { struct device *cb_dev;

• int ret; u32 sid = 0; char name[64]; struct qda_cb_dev *entry;

@@ -30,6 +61,13 @@ int qda_create_cb_device(struct qda_dev *qdev, struct device_node *cb_node) return PTR_ERR(cb_dev); }

• ret = qda_cb_setup_device(qdev, cb_dev, sid);
• if (ret) {

• drm_err(&qdev->drm_dev, "CB device setup failed: %d\n", ret);
  

• device_unregister(cb_dev);
  

• return ret;
  

• }
• entry = kzalloc_obj(*entry); if (!entry) { device_unregister(cb_dev);

@@ -80,6 +118,7 @@ int qda_cb_populate(struct qda_dev *qdev, struct device_node *parent_node) void qda_destroy_cb_device(struct device *cb_dev) { struct iommu_group *group;

• struct qda_iommu_device *iommu_dev;

if (!cb_dev) { pr_debug("qda: NULL CB device passed to destroy\n"); @@ -88,6 +127,14 @@ void qda_destroy_cb_device(struct device *cb_dev) dev_dbg(cb_dev, "Destroying CB device %s\n", dev_name(cb_dev));

• iommu_dev = dev_get_drvdata(cb_dev);
• if (iommu_dev && iommu_dev->qdev && iommu_dev->qdev->iommu_mgr) {

• dev_dbg(cb_dev, "Unregistering IOMMU device for %s\n",
  

• 	dev_name(cb_dev));
  

• qda_memory_manager_unregister_device(iommu_dev->qdev->iommu_mgr,
  

• 				     iommu_dev);
  

• }
• group = iommu_group_get(cb_dev); if (group) { dev_dbg(cb_dev, "Removing %s from IOMMU group\n", dev_name(cb_dev));

diff --git a/drivers/accel/qda/qda_drv.c b/drivers/accel/qda/qda_drv.c index 6c20d6a2fc47..0ad5d9873d7e 100644 --- a/drivers/accel/qda/qda_drv.c +++ b/drivers/accel/qda/qda_drv.c @@ -57,6 +57,40 @@ struct qda_dev *qda_alloc_device(struct device *dev) return qdev; } +static void cleanup_memory_manager(struct qda_dev *qdev)

Prefixes...

ack>

...

+{

• if (qdev->iommu_mgr) {

• qda_memory_manager_exit(qdev->iommu_mgr);
  

• kfree(qdev->iommu_mgr);
  

• qdev->iommu_mgr = NULL;
  

• }

+}

+static int init_memory_manager(struct qda_dev *qdev) +{

• qdev->iommu_mgr = kzalloc_obj(*qdev->iommu_mgr);
• if (!qdev->iommu_mgr)

• return -ENOMEM;
  

• return qda_memory_manager_init(qdev->iommu_mgr);

+}

+void qda_deinit_device(struct qda_dev *qdev) +{

• cleanup_memory_manager(qdev);

Ugh, inline all your one-line wrappers.

ack>

...

+}

+int qda_init_device(struct qda_dev *qdev) +{

• int ret;
• ret = init_memory_manager(qdev);
• if (ret)

• drm_err(&qdev->drm_dev, "Failed to initialize memory manager: %d\n", ret);
  

• return ret;

+}

void qda_unregister_device(struct qda_dev *qdev) { drm_dev_unregister(&qdev->drm_dev); diff --git a/drivers/accel/qda/qda_drv.h b/drivers/accel/qda/qda_drv.h index 2715f378775d..eb089e586b17 100644 --- a/drivers/accel/qda/qda_drv.h +++ b/drivers/accel/qda/qda_drv.h @@ -13,6 +13,7 @@ #include <drm/drm_device.h> #include <drm/drm_drv.h> #include <drm/drm_file.h> +#include "qda_memory_manager.h" /* Driver identification */ #define QDA_DRIVER_NAME "qda" @@ -40,6 +41,8 @@ struct qda_dev { struct device *dev; /** @cb_devs: Compute context-bank (CB) child devices */ struct list_head cb_devs;

• /** @iommu_mgr: IOMMU/memory manager instance */
• struct qda_memory_manager *iommu_mgr; /** @dsp_name: Name of the DSP domain (e.g. "cdsp", "adsp") */ const char *dsp_name;

}; @@ -59,6 +62,8 @@ static inline struct qda_dev *qda_dev_from_drm(struct drm_device *dev) struct qda_dev *qda_alloc_device(struct device *dev); /* Core device lifecycle */ +int qda_init_device(struct qda_dev *qdev); +void qda_deinit_device(struct qda_dev *qdev); int qda_register_device(struct qda_dev *qdev); void qda_unregister_device(struct qda_dev *qdev); diff --git a/drivers/accel/qda/qda_memory_manager.c b/drivers/accel/qda/qda_memory_manager.c new file mode 100644 index 000000000000..00a9c0ae4224 --- /dev/null +++ b/drivers/accel/qda/qda_memory_manager.c @@ -0,0 +1,111 @@ +// SPDX-License-Identifier: GPL-2.0-only +// Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.

+#include <linux/refcount.h> +#include <linux/slab.h> +#include <linux/spinlock.h> +#include <linux/xarray.h> +#include <drm/drm_file.h> +#include "qda_drv.h" +#include "qda_memory_manager.h"

+static void cleanup_all_memory_devices(struct qda_memory_manager *mem_mgr) +{

• unsigned long index;
• void *entry;
• pr_debug("qda: Starting cleanup of all memory devices\n");

pr_debug is a third way to debug. Stop it, please.

ack>

...

• xa_for_each(&mem_mgr->device_xa, index, entry) {

• struct qda_iommu_device *iommu_dev = entry;
  

• pr_debug("qda: Cleaning up device id=%lu\n", index);
  

• xa_erase(&mem_mgr->device_xa, index);
  

• kfree(iommu_dev);
  

• }
• pr_debug("qda: Completed cleanup of all memory devices\n");

+}