linux-kernel - Re: [PATCH v4 1/2] drm/virtio: Refactor job submission code path

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Message-ID: <ZCWre6oy0vHNyIkW@arch-x395>
Date:   Thu, 30 Mar 2023 16:32:11 +0100
From:   Emil Velikov <emil.velikov@...labora.com>
To:     Dmitry Osipenko <dmitry.osipenko@...labora.com>
Cc:     David Airlie <airlied@...hat.com>,
        Gerd Hoffmann <kraxel@...hat.com>,
        Gurchetan Singh <gurchetansingh@...omium.org>,
        Chia-I Wu <olvaffe@...il.com>, Daniel Vetter <daniel@...ll.ch>,
        Rob Clark <robdclark@...il.com>,
        Marek Olšák <maraeo@...il.com>,
        Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@....com>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        kernel@...labora.com, virtualization@...ts.linux-foundation.org
Subject: Re: [PATCH v4 1/2] drm/virtio: Refactor job submission code path

Hey Dmitry,

On 2023/03/24, Dmitry Osipenko wrote:
> Move virtio_gpu_execbuffer_ioctl() into separate virtgpu_submit.c file
> and refactor the code along the way to ease addition of new features to
> the ioctl.
> 

At a glance, we have a handful of no-op as well as some functional
changes - let's split those up in separate patches.

> Reviewed-by: Rob Clark <robdclark@...il.com>
> Signed-off-by: Dmitry Osipenko <dmitry.osipenko@...labora.com>
> ---


> +static int virtio_gpu_dma_fence_wait(struct virtio_gpu_submit *submit,
> +				     struct dma_fence *fence)
> +{
> +	struct dma_fence_unwrap itr;
> +	struct dma_fence *f;
> +	int err;
> +
> +	dma_fence_unwrap_for_each(f, &itr, fence) {

The dma_fence_unwrap_for_each() change should be a separate patch,
highlighting why we want it.

> +		err = virtio_gpu_do_fence_wait(submit, f);
> +		if (err)
> +			return err;
> +	}
> +
> +	return 0;
> +}
> +


> +	ret = virtio_gpu_init_submit(&submit, exbuf, dev, file,
> +				     fence_ctx, ring_idx);
> +	if (ret)
> +		goto cleanup;
> +
> +	ret = virtio_gpu_wait_in_fence(&submit);
> +	if (ret)
> +		goto cleanup;
> +

We have reshuffled the order around in_fence waiting, out_fence install,
handles, cmdbuf, drm events, etc. Can we get that split up a bit, with
some comments.

If it were me, I would keep the wait_in_fence early and inline
virtio_gpu_init_submit (the nesting/abstraction seems a bit much). This
means one can omit the virtio_gpu_submit::exbuf all together.


HTH
Emil