[Linaro-mm-sig] Re: [PATCH RFC 11/18] accel/qda: Add GEM_CREATE and GEM_MMAP_OFFSET IOCTLs

On 2/24/2026 4:09 AM, Dmitry Baryshkov wrote:

On Tue, Feb 24, 2026 at 12:39:05AM +0530, Ekansh Gupta wrote:

...

Add two GEM-related IOCTLs for the QDA accelerator driver and hook them into the DRM accel driver. DRM_IOCTL_QDA_GEM_CREATE allocates a DMA-backed GEM buffer object via qda_gem_create_object() and returns a GEM handle to userspace, while DRM_IOCTL_QDA_GEM_MMAP_OFFSET returns a valid mmap offset for a given GEM handle using drm_gem_create_mmap_offset() and the vma_node in the GEM object.

The QDA driver is updated to advertise DRIVER_GEM in its driver_features, and the new IOCTLs are wired through the QDA GEM and memory-manager backend. These IOCTLs allow userspace to allocate buffers and map them into its address space as a first step toward full compute buffer management and integration with DSP workloads.

Signed-off-by: Ekansh Gupta ekansh.gupta@oss.qualcomm.com

drivers/accel/qda/qda_drv.c | 5 ++++- drivers/accel/qda/qda_gem.h | 30 ++++++++++++++++++++++++++++++ drivers/accel/qda/qda_ioctl.c | 35 +++++++++++++++++++++++++++++++++++ include/uapi/drm/qda_accel.h | 36 ++++++++++++++++++++++++++++++++++++ 4 files changed, 105 insertions(+), 1 deletion(-)

diff --git a/drivers/accel/qda/qda_drv.c b/drivers/accel/qda/qda_drv.c index 19798359b14e..0dd0e2bb2c0f 100644 --- a/drivers/accel/qda/qda_drv.c +++ b/drivers/accel/qda/qda_drv.c @@ -12,6 +12,7 @@ #include <drm/qda_accel.h> #include "qda_drv.h" +#include "qda_gem.h" #include "qda_ioctl.h" #include "qda_rpmsg.h" @@ -154,10 +155,12 @@ DEFINE_DRM_ACCEL_FOPS(qda_accel_fops); static const struct drm_ioctl_desc qda_ioctls[] = { DRM_IOCTL_DEF_DRV(QDA_QUERY, qda_ioctl_query, 0),

• DRM_IOCTL_DEF_DRV(QDA_GEM_CREATE, qda_ioctl_gem_create, 0),
• DRM_IOCTL_DEF_DRV(QDA_GEM_MMAP_OFFSET, qda_ioctl_gem_mmap_offset, 0),

}; static struct drm_driver qda_drm_driver = {

• .driver_features = DRIVER_COMPUTE_ACCEL,

• .driver_features = DRIVER_GEM | DRIVER_COMPUTE_ACCEL, .fops = &qda_accel_fops, .open = qda_open, .postclose = qda_postclose,

diff --git a/drivers/accel/qda/qda_gem.h b/drivers/accel/qda/qda_gem.h index caae9cda5363..cbd5d0a58fa4 100644 --- a/drivers/accel/qda/qda_gem.h +++ b/drivers/accel/qda/qda_gem.h @@ -47,6 +47,36 @@ struct drm_gem_object *qda_gem_create_object(struct drm_device *drm_dev, void qda_gem_free_object(struct drm_gem_object *gem_obj); int qda_gem_mmap_obj(struct drm_gem_object *gem_obj, struct vm_area_struct *vma); +/*

• • GEM IOCTL handlers
• */

+/**

• • qda_ioctl_gem_create - Create a GEM buffer object
• • @dev: DRM device structure
• • @data: User-space data containing buffer creation parameters
• • @file_priv: DRM file private data
• • This IOCTL handler creates a new GEM buffer object with the specified
• • size and returns a handle to the created buffer.
• • Return: 0 on success, negative error code on failure
• */

+int qda_ioctl_gem_create(struct drm_device *dev, void *data, struct drm_file *file_priv);

+/**

• • qda_ioctl_gem_mmap_offset - Get mmap offset for a GEM buffer object
• • @dev: DRM device structure
• • @data: User-space data containing buffer handle and offset result
• • @file_priv: DRM file private data
• • This IOCTL handler retrieves the mmap offset for a GEM buffer object,
• • which can be used to map the buffer into user-space memory.
• • Return: 0 on success, negative error code on failure
• */

+int qda_ioctl_gem_mmap_offset(struct drm_device *dev, void *data, struct drm_file *file_priv);

/*

• Helper functions for GEM object allocation and cleanup
• These are used internally and by the PRIME import code

diff --git a/drivers/accel/qda/qda_ioctl.c b/drivers/accel/qda/qda_ioctl.c index 9fa73ec2dfce..ef3c9c691cb7 100644 --- a/drivers/accel/qda/qda_ioctl.c +++ b/drivers/accel/qda/qda_ioctl.c @@ -43,3 +43,38 @@ int qda_ioctl_query(struct drm_device *dev, void *data, struct drm_file *file_pr return 0; }

+int qda_ioctl_gem_create(struct drm_device *dev, void *data, struct drm_file *file_priv) +{

• struct drm_qda_gem_create *args = data;
• struct drm_gem_object *gem_obj;
• struct qda_drm_priv *drm_priv;
• drm_priv = get_drm_priv_from_device(dev);
• if (!drm_priv || !drm_priv->iommu_mgr)

• return -EINVAL;
  

• gem_obj = qda_gem_create_object(dev, drm_priv->iommu_mgr, args->size, file_priv);
• if (IS_ERR(gem_obj))

• return PTR_ERR(gem_obj);
  

• return qda_gem_create_handle(file_priv, gem_obj, &args->handle);

+}

+int qda_ioctl_gem_mmap_offset(struct drm_device *dev, void *data, struct drm_file *file_priv) +{

• struct drm_qda_gem_mmap_offset *args = data;
• struct drm_gem_object *gem_obj;
• int ret;
• gem_obj = qda_gem_lookup_object(file_priv, args->handle);
• if (IS_ERR(gem_obj))

• return PTR_ERR(gem_obj);
  

• ret = drm_gem_create_mmap_offset(gem_obj);
• if (ret == 0)

• args->offset = drm_vma_node_offset_addr(&gem_obj->vma_node);
  

• drm_gem_object_put(gem_obj);
• return ret;

+} diff --git a/include/uapi/drm/qda_accel.h b/include/uapi/drm/qda_accel.h index 0aad791c4832..ed24a7f5637e 100644 --- a/include/uapi/drm/qda_accel.h +++ b/include/uapi/drm/qda_accel.h @@ -19,6 +19,8 @@ extern "C" {

• They are used with DRM_COMMAND_BASE to create the full IOCTL numbers.

*/ #define DRM_QDA_QUERY 0x00 +#define DRM_QDA_GEM_CREATE 0x01 +#define DRM_QDA_GEM_MMAP_OFFSET 0x02 /*

• QDA IOCTL definitions

@@ -27,6 +29,10 @@ extern "C" {

• data structure and direction (read/write) for each IOCTL.

*/ #define DRM_IOCTL_QDA_QUERY DRM_IOR(DRM_COMMAND_BASE + DRM_QDA_QUERY, struct drm_qda_query) +#define DRM_IOCTL_QDA_GEM_CREATE DRM_IOWR(DRM_COMMAND_BASE + DRM_QDA_GEM_CREATE, \

• 				 struct drm_qda_gem_create)
  

+#define DRM_IOCTL_QDA_GEM_MMAP_OFFSET DRM_IOWR(DRM_COMMAND_BASE + DRM_QDA_GEM_MMAP_OFFSET, \

• 				 struct drm_qda_gem_mmap_offset)
  

/**

• struct drm_qda_query - Device information query structure

@@ -40,6 +46,36 @@ struct drm_qda_query { __u8 dsp_name[16]; }; +/**

• • struct drm_qda_gem_create - GEM buffer object creation parameters
• • @size: Size of the GEM object to create in bytes (input)
• • @handle: Allocated GEM handle (output)
• • This structure is used with DRM_IOCTL_QDA_GEM_CREATE to allocate
• • a new GEM buffer object.
• */

+struct drm_qda_gem_create {

• __u32 handle;
• __u32 pad;
• __u64 size;

If you put size before handle, you would not need padding.

ack

...

+};

+/**

• • struct drm_qda_gem_mmap_offset - GEM object mmap offset query
• • @handle: GEM handle (input)
• • @pad: Padding for 64-bit alignment
• • @offset: mmap offset for the GEM object (output)
• • This structure is used with DRM_IOCTL_QDA_GEM_MMAP_OFFSET to retrieve
• • the mmap offset that can be used with mmap() to map the GEM object into
• • user space.
• */

+struct drm_qda_gem_mmap_offset {

• __u32 handle;
• __u32 pad;
• __u64 offset;

I'm really not a fan of the pad field in the middle of the structure.

ack

...

+};

#if defined(__cplusplus) } #endif

-- 2.34.1