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 <[email protected]>
>>
>> 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 <[email protected]>
>> ---
>> 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");
>> +}
>> +
>
