Re: [PATCH v8 04/10] accel/rocket: Add job submission IOCTL

On 7/13/2025 2:38 AM, Tomeu Vizoso wrote:

Using the DRM GPU scheduler infrastructure, with a scheduler for each
core.

Userspace can decide for a series of tasks to be executed sequentially
in the same core, so SRAM locality can be taken advantage of.

The job submission code was initially based on Panfrost.

v2:
- Remove hardcoded number of cores
- Misc. style fixes (Jeffrey Hugo)
- Repack IOCTL struct (Jeffrey Hugo)

v3:
- Adapt to a split of the register block in the DT bindings (Nicolas
   Frattaroli)
- Make use of GPL-2.0-only for the copyright notice (Jeff Hugo)
- Use drm_* logging functions (Thomas Zimmermann)
- Rename reg i/o macros (Thomas Zimmermann)
- Add padding to ioctls and check for zero (Jeff Hugo)
- Improve error handling (Nicolas Frattaroli)

v6:
- Use mutexes guard (Markus Elfring)
- Use u64_to_user_ptr (Jeff Hugo)
- Drop rocket_fence (Rob Herring)

v7:
- Assign its own IOMMU domain to each client, for isolation (Daniel
   Stone and Robin Murphy)

v8:
- Use reset lines to reset the cores (Robin Murphy)
- Use the macros to compute the values for the bitfields (Robin Murphy)
- More descriptive name for the IRQ (Robin Murphy)
- Simplify job interrupt handing (Robin Murphy)
- Correctly acquire a reference to the IOMMU (Robin Murphy)
- Specify the size of the embedded structs in the IOCTLs for future
   extensibility (Rob Herring)
- Expose only 32 bits for the address of the regcmd BO (Robin Murphy)

Tested-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Tomeu Vizoso <tomeu@tomeuvizoso.net>

Reviewed-by: Jeff Hugo <jeff.hugo@oss.qualcomm.com>

One optional nit below -

+/**
+ * struct drm_rocket_submit - ioctl argument for submitting commands to the NPU.
+ *
+ * The kernel will schedule the execution of these jobs in dependency order.
+ */
+struct drm_rocket_submit {
+	/** Input: Pointer to an array of struct drm_rocket_job. */
+	__u64 jobs;
+
+	/** Input: Number of jobs passed in. */
+	__u32 job_count;
+
+	/** Input: Size in bytes of the structs in the @jobs field. */
+	__u32 job_struct_size;
+
+	/** Reserved, must be zero. */
+	__u64 reserved;

It does not appear that this field is needed for padding, and I don't 
see the rest of the series using this. This could be dropped, although 
maybe you have a use for it in the near future?