Re: [PATCH RFC 07/18] accel/qda: Add DRM accel device registration for QDA driver

[Ekansh Gupta <ekansh.gupta@oss.qualcomm.com>]

On 2/24/2026 3:46 AM, Dmitry Baryshkov wrote:
> On Tue, Feb 24, 2026 at 12:39:01AM +0530, Ekansh Gupta wrote:
>> Add DRM accel integration for the QDA DSP accelerator driver. A new
>> qda_drm_priv structure is introduced to hold per-device DRM state,
>> including a pointer to the memory manager and the parent qda_dev
>> instance. The driver now allocates a drm_device, initializes
>> driver-private state, and registers the device via the DRM accel
>> infrastructure.
>>
>> qda_register_device() performs allocation and registration of the DRM
>> device, while qda_unregister_device() handles device teardown and
>> releases references using drm_dev_unregister() and drm_dev_put().
>> Initialization and teardown paths are updated so DRM resources are
>> allocated after IOMMU/memory-manager setup and cleaned during RPMsg
>> remove.
>>
>> This patch lays the foundation for adding GEM buffer support and IOCTL
>> handling in later patches as part of the compute accelerator interface.
>>
>> Signed-off-by: Ekansh Gupta <ekansh.gupta@oss.qualcomm.com>
>> ---
>>  drivers/accel/qda/qda_drv.c   | 103 ++++++++++++++++++++++++++++++++++++++++++
>>  drivers/accel/qda/qda_drv.h   |  33 +++++++++++++-
>>  drivers/accel/qda/qda_rpmsg.c |   8 ++++
>>  3 files changed, 142 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/accel/qda/qda_drv.c b/drivers/accel/qda/qda_drv.c
>> index 69132737f964..a9113ec78fa2 100644
>> --- a/drivers/accel/qda/qda_drv.c
>> +++ b/drivers/accel/qda/qda_drv.c
>> @@ -4,9 +4,31 @@
>>  #include <linux/kernel.h>
>>  #include <linux/atomic.h>
>>  #include <linux/slab.h>
>> +#include <drm/drm_accel.h>
>> +#include <drm/drm_drv.h>
>> +#include <drm/drm_file.h>
>> +#include <drm/drm_gem.h>
>> +#include <drm/drm_ioctl.h>
>>  #include "qda_drv.h"
>>  #include "qda_rpmsg.h"
>>  
>> +DEFINE_DRM_ACCEL_FOPS(qda_accel_fops);
>> +
>> +static struct drm_driver qda_drm_driver = {
>> +	.driver_features = DRIVER_COMPUTE_ACCEL,
>> +	.fops			= &qda_accel_fops,
> Strange indentation in the middle. Please drop it.
ack.
>
>> +	.name = DRIVER_NAME,
>> +	.desc = "Qualcomm DSP Accelerator Driver",
>> +};
>> +
>> +static void cleanup_drm_private(struct qda_dev *qdev)
>> +{
>> +	if (qdev->drm_priv) {
>> +		qda_dbg(qdev, "Cleaning up DRM private data\n");
>> +		kfree(qdev->drm_priv);
>> +	}
>> +}
>> +
>>  static void cleanup_iommu_manager(struct qda_dev *qdev)
>>  {
>>  	if (qdev->iommu_mgr) {
>> @@ -24,6 +46,7 @@ static void cleanup_device_resources(struct qda_dev *qdev)
>>  
>>  void qda_deinit_device(struct qda_dev *qdev)
>>  {
>> +	cleanup_drm_private(qdev);
>>  	cleanup_iommu_manager(qdev);
>>  	cleanup_device_resources(qdev);
>>  }
>> @@ -59,6 +82,18 @@ static int init_memory_manager(struct qda_dev *qdev)
>>  	return 0;
>>  }
>>  
>> +static int init_drm_private(struct qda_dev *qdev)
>> +{
>> +	qda_dbg(qdev, "Initializing DRM private data\n");
>> +
>> +	qdev->drm_priv = kzalloc_obj(*qdev->drm_priv, GFP_KERNEL);
>> +	if (!qdev->drm_priv)
>> +		return -ENOMEM;
>> +
>> +	qda_dbg(qdev, "DRM private data initialized successfully\n");
>> +	return 0;
>> +}
>> +
>>  int qda_init_device(struct qda_dev *qdev)
>>  {
>>  	int ret;
>> @@ -71,14 +106,82 @@ int qda_init_device(struct qda_dev *qdev)
>>  		goto err_cleanup_resources;
>>  	}
>>  
>> +	ret = init_drm_private(qdev);
>> +	if (ret) {
>> +		qda_err(qdev, "DRM private data initialization failed: %d\n", ret);
>> +		goto err_cleanup_iommu;
>> +	}
>> +
>>  	qda_dbg(qdev, "QDA device initialized successfully\n");
>>  	return 0;
>>  
>> +err_cleanup_iommu:
>> +	cleanup_iommu_manager(qdev);
>>  err_cleanup_resources:
>>  	cleanup_device_resources(qdev);
>>  	return ret;
>>  }
>>  
>> +static int setup_and_register_drm_device(struct qda_dev *qdev)
>> +{
>> +	struct drm_device *ddev;
>> +	int ret;
>> +
>> +	qda_dbg(qdev, "Setting up and registering DRM device\n");
>> +
>> +	ddev = drm_dev_alloc(&qda_drm_driver, qdev->dev);
> devm_drm_dev_alloc() please. Move this patch to the front of the series,
> making everything else depend on the allocated data structure.
ack.
>
>> +	if (IS_ERR(ddev)) {
>> +		ret = PTR_ERR(ddev);
>> +		qda_err(qdev, "Failed to allocate DRM device: %d\n", ret);
>> +		return ret;
>> +	}
>> +
>> +	qdev->drm_priv->drm_dev = ddev;
>> +	qdev->drm_priv->iommu_mgr = qdev->iommu_mgr;
>> +	qdev->drm_priv->qdev = qdev;
>> +
>> +	ddev->dev_private = qdev->drm_priv;
>> +	qdev->drm_dev = ddev;
>> +
>> +	ret = drm_dev_register(ddev, 0);
>> +	if (ret) {
>> +		qda_err(qdev, "Failed to register DRM device: %d\n", ret);
>> +		drm_dev_put(ddev);
>> +		return ret;
>> +	}
>> +
>> +	qda_dbg(qdev, "DRM device registered successfully\n");
>> +	return 0;
>> +}
>> +
>> +int qda_register_device(struct qda_dev *qdev)
>> +{
>> +	int ret;
>> +
>> +	ret = setup_and_register_drm_device(qdev);
>> +	if (ret) {
>> +		qda_err(qdev, "DRM device setup failed: %d\n", ret);
>> +		return ret;
>> +	}
>> +
>> +	qda_dbg(qdev, "QDA device registered successfully\n");
>> +	return 0;
>> +}
>> +
>> +void qda_unregister_device(struct qda_dev *qdev)
>> +{
>> +	qda_info(qdev, "Unregistering QDA device\n");
>> +
>> +	if (qdev->drm_dev) {
>> +		qda_dbg(qdev, "Unregistering DRM device\n");
>> +		drm_dev_unregister(qdev->drm_dev);
>> +		drm_dev_put(qdev->drm_dev);
>> +		qdev->drm_dev = NULL;
>> +	}
>> +
>> +	qda_dbg(qdev, "QDA device unregistered successfully\n");
>> +}
>> +
>>  static int __init qda_core_init(void)
>>  {
>>  	int ret;
>> diff --git a/drivers/accel/qda/qda_drv.h b/drivers/accel/qda/qda_drv.h
>> index 2cb97e4eafbf..2b80401a3741 100644
>> --- a/drivers/accel/qda/qda_drv.h
>> +++ b/drivers/accel/qda/qda_drv.h
>> @@ -11,13 +11,35 @@
>>  #include <linux/mutex.h>
>>  #include <linux/rpmsg.h>
>>  #include <linux/xarray.h>
>> +#include <drm/drm_drv.h>
>> +#include <drm/drm_file.h>
>> +#include <drm/drm_device.h>
>> +#include <drm/drm_accel.h>
>>  #include "qda_memory_manager.h"
>>  
>>  /* Driver identification */
>>  #define DRIVER_NAME "qda"
>>  
>> +/**
>> + * struct qda_drm_priv - DRM device private data for QDA device
>> + *
>> + * This structure serves as the DRM device private data (stored in dev_private),
>> + * bridging the DRM device context with the QDA device and providing access to
>> + * shared resources like the memory manager during buffer operations.
>> + */
>> +struct qda_drm_priv {
> Shared between what and what? Why do you need a separate structure
> instead of using qda_dev?
This is for channel specific resources which will be used by all processes using the channel. It
should be possible to use qda_dev, I'll try it out and fix this in next version.
>
>> +	/* DRM device structure */
>> +	struct drm_device *drm_dev;
>> +	/* Global memory/IOMMU manager */
>> +	struct qda_memory_manager *iommu_mgr;
>> +	/* Back-pointer to qda_dev */
>> +	struct qda_dev *qdev;
>> +};
>> +
>>  /* struct qda_dev - Main device structure for QDA driver */
>>  struct qda_dev {
>> +	/* DRM device for accelerator interface */
>> +	struct drm_device *drm_dev;
> Drop the pointer here.
I'll modify this based on qda_drm_priv replacement.
>
>>  	/* RPMsg device for communication with remote processor */
>>  	struct rpmsg_device *rpdev;
>>  	/* Underlying device structure */
>> @@ -26,6 +48,8 @@ struct qda_dev {
>>  	struct mutex lock;
>>  	/* IOMMU/memory manager */
>>  	struct qda_memory_manager *iommu_mgr;
>> +	/* DRM device private data */
>> +	struct qda_drm_priv *drm_priv;
>>  	/* Flag indicating device removal in progress */
>>  	atomic_t removing;
>>  	/* Name of the DSP (e.g., "cdsp", "adsp") */
>> @@ -39,8 +63,8 @@ struct qda_dev {
>>   * @qdev: QDA device structure
>>   *
>>   * Returns the most appropriate device structure for logging messages.
>> - * Prefers qdev->dev, or returns NULL if the device is being removed
>> - * or invalid.
>> + * Prefers qdev->dev, falls back to qdev->drm_dev->dev, or returns NULL
>> + * if the device is being removed or invalid.
>>   */
>>  static inline struct device *qda_get_log_device(struct qda_dev *qdev)
>>  {
>> @@ -50,6 +74,9 @@ static inline struct device *qda_get_log_device(struct qda_dev *qdev)
>>  	if (qdev->dev)
>>  		return qdev->dev;
>>  
>> +	if (qdev->drm_dev)
>> +		return qdev->drm_dev->dev;
>> +
>>  	return NULL;
>>  }
>>  
>> @@ -93,5 +120,7 @@ static inline struct device *qda_get_log_device(struct qda_dev *qdev)
>>   */
>>  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);
>>  
>>  #endif /* __QDA_DRV_H__ */
>> diff --git a/drivers/accel/qda/qda_rpmsg.c b/drivers/accel/qda/qda_rpmsg.c
>> index 5a57384de6a2..b2b44b4d3ca8 100644
>> --- a/drivers/accel/qda/qda_rpmsg.c
>> +++ b/drivers/accel/qda/qda_rpmsg.c
>> @@ -80,6 +80,7 @@ static void qda_rpmsg_remove(struct rpmsg_device *rpdev)
>>  	qdev->rpdev = NULL;
>>  	mutex_unlock(&qdev->lock);
>>  
>> +	qda_unregister_device(qdev);
>>  	qda_unpopulate_child_devices(qdev);
>>  	qda_deinit_device(qdev);
>>  
>> @@ -123,6 +124,13 @@ static int qda_rpmsg_probe(struct rpmsg_device *rpdev)
>>  		return ret;
>>  	}
>>  
>> +	ret = qda_register_device(qdev);
>> +	if (ret) {
>> +		qda_deinit_device(qdev);
>> +		qda_unpopulate_child_devices(qdev);
>> +		return ret;
>> +	}
>> +
>>  	qda_info(qdev, "QDA RPMsg probe completed successfully for %s\n", qdev->dsp_name);
>>  	return 0;
>>  }
>>
>> -- 
>> 2.34.1
>>