Re: [PATCH 08/15] accel/qda: Add QUERY IOCTL and QDA UAPI header

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

On 20-05-2026 19:59, Dmitry Baryshkov wrote:
> On Tue, May 19, 2026 at 11:45:58AM +0530, Ekansh Gupta via B4 Relay wrote:
>> From: Ekansh Gupta <ekansh.gupta@oss.qualcomm.com>
>>
>> Introduce the DRM_IOCTL_QDA_QUERY IOCTL, which allows user-space to
>> identify which DSP domain a given /dev/accel/accel* node represents
>> (e.g. "cdsp", "adsp").
>>
>> include/uapi/drm/qda_accel.h
>>   Defines the QDA IOCTL command numbers and the associated data
>>   structures. The header follows the standard DRM UAPI conventions:
>>   __u8/__u32 types, a C++ extern "C" guard, and GPL-2.0-only WITH
>>   Linux-syscall-note licensing.
>>
>> drivers/accel/qda/qda_ioctl.c / qda_ioctl.h
>>   Implements qda_ioctl_query(), which copies the DSP domain name
>>   stored in qda_dev.dsp_name into the user-supplied drm_qda_query
>>   buffer using strscpy().
>>
>> drivers/accel/qda/qda_drv.c
>>   Registers the qda_ioctls[] table with the drm_driver so that the
>>   DRM core dispatches DRM_IOCTL_QDA_QUERY to qda_ioctl_query().
>>
>> 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_drv.c   |  8 +++++++
>>  drivers/accel/qda/qda_ioctl.c | 26 +++++++++++++++++++++++
>>  drivers/accel/qda/qda_ioctl.h | 13 ++++++++++++
>>  include/uapi/drm/qda_accel.h  | 49 +++++++++++++++++++++++++++++++++++++++++++
>>  5 files changed, 97 insertions(+)
>>
>> diff --git a/drivers/accel/qda/Makefile b/drivers/accel/qda/Makefile
>> index 701fad5ffb50..b658dad35fee 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_ioctl.o \
>>  	qda_memory_manager.o \
>>  	qda_rpmsg.o
>>  
>> diff --git a/drivers/accel/qda/qda_drv.c b/drivers/accel/qda/qda_drv.c
>> index 0ad5d9873d7e..becd831d10be 100644
>> --- a/drivers/accel/qda/qda_drv.c
>> +++ b/drivers/accel/qda/qda_drv.c
>> @@ -8,8 +8,10 @@
>>  #include <drm/drm_gem.h>
>>  #include <drm/drm_ioctl.h>
>>  #include <drm/drm_print.h>
>> +#include <drm/qda_accel.h>
>>  
>>  #include "qda_drv.h"
>> +#include "qda_ioctl.h"
>>  #include "qda_rpmsg.h"
>>  
>>  static int qda_open(struct drm_device *dev, struct drm_file *file)
>> @@ -36,11 +38,17 @@ static void qda_postclose(struct drm_device *dev, struct drm_file *file)
>>  
>>  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),
>> +};
>> +
>>  static const struct drm_driver qda_drm_driver = {
>>  	.driver_features = DRIVER_COMPUTE_ACCEL,
>>  	.fops = &qda_accel_fops,
>>  	.open = qda_open,
>>  	.postclose = qda_postclose,
>> +	.ioctls = qda_ioctls,
>> +	.num_ioctls = ARRAY_SIZE(qda_ioctls),
>>  	.name = QDA_DRIVER_NAME,
>>  	.desc = "Qualcomm DSP Accelerator Driver",
>>  };
>> diff --git a/drivers/accel/qda/qda_ioctl.c b/drivers/accel/qda/qda_ioctl.c
>> new file mode 100644
>> index 000000000000..761d3567c33f
>> --- /dev/null
>> +++ b/drivers/accel/qda/qda_ioctl.c
>> @@ -0,0 +1,26 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +// Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
>> +#include <drm/drm_ioctl.h>
>> +#include <drm/qda_accel.h>
>> +#include "qda_drv.h"
>> +#include "qda_ioctl.h"
>> +
>> +/**
>> + * qda_ioctl_query() - Query DSP device information
>> + * @dev: DRM device structure
>> + * @data: User-space data (struct drm_qda_query)
>> + * @file_priv: DRM file private data
>> + *
>> + * Return: 0 on success, negative error code on failure
>> + */
>> +int qda_ioctl_query(struct drm_device *dev, void *data, struct drm_file *file_priv)
>> +{
>> +	struct drm_qda_query *args = data;
>> +	struct qda_dev *qdev;
>> +
>> +	qdev = qda_dev_from_drm(dev);
>> +
>> +	strscpy(args->dsp_name, qdev->dsp_name, sizeof(args->dsp_name));
>> +
>> +	return 0;
>> +}
>> diff --git a/drivers/accel/qda/qda_ioctl.h b/drivers/accel/qda/qda_ioctl.h
>> new file mode 100644
>> index 000000000000..b8fd536a111f
>> --- /dev/null
>> +++ b/drivers/accel/qda/qda_ioctl.h
>> @@ -0,0 +1,13 @@
>> +/* SPDX-License-Identifier: GPL-2.0-only */
>> +/*
>> + * Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
>> + */
>> +
>> +#ifndef __QDA_IOCTL_H__
>> +#define __QDA_IOCTL_H__
>> +
>> +#include "qda_drv.h"
>> +
>> +int qda_ioctl_query(struct drm_device *dev, void *data, struct drm_file *file_priv);
>> +
>> +#endif /* __QDA_IOCTL_H__ */
>> diff --git a/include/uapi/drm/qda_accel.h b/include/uapi/drm/qda_accel.h
>> new file mode 100644
>> index 000000000000..1971a4263065
>> --- /dev/null
>> +++ b/include/uapi/drm/qda_accel.h
>> @@ -0,0 +1,49 @@
>> +/* SPDX-License-Identifier: GPL-2.0-only WITH Linux-syscall-note */
>> +/*
>> + * Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
>> + */
>> +
>> +#ifndef __QDA_ACCEL_H__
>> +#define __QDA_ACCEL_H__
>> +
>> +#include "drm.h"
>> +
>> +#if defined(__cplusplus)
>> +extern "C" {
>> +#endif
>> +
>> +/*
>> + * QDA IOCTL command numbers
>> + *
>> + * These define the command numbers for QDA-specific IOCTLs.
>> + * They are used with DRM_COMMAND_BASE to create the full IOCTL numbers.
>> + */
>> +#define DRM_QDA_QUERY		0x00
>> +
>> +/*
>> + * QDA IOCTL definitions
>> + *
>> + * These macros define the actual IOCTL numbers used by userspace applications.
>> + * They combine the command numbers with DRM_COMMAND_BASE and specify the
>> + * 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)
>> +
>> +/**
>> + * struct drm_qda_query - Device information query structure
>> + * @dsp_name: Name of DSP (e.g., "adsp", "cdsp", "cdsp1", "gdsp0", "gdsp1")
>> + *
>> + * This structure is used with DRM_IOCTL_QDA_QUERY to query device type,
>> + * allowing userspace to identify which DSP a device node represents. The
>> + * kernel provides the DSP name directly as a null-terminated string.
>> + */
>> +struct drm_qda_query {
>> +	__u8 dsp_name[16];
> 
> Are you sure that you want to query only the name? No extra options, no
> attributes, no hardware capabilities?
There are plans to extend this ioctl to support DSP capabilities and few
other query options, but as per my understanding, I don't need to add
reserved IOCTLs in drm case and I can extend it in future. Please
correct me if my understanding is wrong and I should add reserved fields.

Copying the statement from the doc[1].
"Note that drm_ioctl() automatically zero-extends structures, hence make
sure you can add more stuff at the end, i.e. don’t put a variable sized
array there."

[1]
https://www.kernel.org/doc/html/v7.0/gpu/drm-uapi.html#ioctl-support-on-device-nodes>

>> +};
>> +
>> +#if defined(__cplusplus)
>> +}
>> +#endif
>> +
>> +#endif /* __QDA_ACCEL_H__ */
>>
>> -- 
>> 2.34.1
>>
>>
>