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

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Message-ID: <cd36e463-2499-4e3f-8a02-60ea43de83dd@oss.qualcomm.com>
Date: Fri, 18 Jul 2025 11:26:45 -0600
From: Jeff Hugo <jeff.hugo@....qualcomm.com>
To: Tomeu Vizoso <tomeu@...euvizoso.net>, Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley
 <conor+dt@...nel.org>, Heiko Stuebner <heiko@...ech.de>,
        Oded Gabbay <ogabbay@...nel.org>, Jonathan Corbet <corbet@....net>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
        Sumit Semwal <sumit.semwal@...aro.org>,
        Christian König <christian.koenig@....com>,
        Sebastian Reichel <sebastian.reichel@...labora.com>,
        Nicolas Frattaroli <nicolas.frattaroli@...labora.com>,
        Kever Yang <kever.yang@...k-chips.com>,
        Robin Murphy <robin.murphy@....com>,
        Daniel Stone <daniel@...ishbar.org>, Da Xue <da@...re.computer>,
        Philipp Zabel <p.zabel@...gutronix.de>
Cc: devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, linux-doc@...r.kernel.org,
        linux-media@...r.kernel.org, linaro-mm-sig@...ts.linaro.org
Subject: 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@...ech.de>
> Signed-off-by: Tomeu Vizoso <tomeu@...euvizoso.net>

Reviewed-by: Jeff Hugo <jeff.hugo@....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?