netdev - Re: [MAINTAINERS SUMMIT] Device Passthrough Considered Harmful?

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Message-ID: <20240802150753.GC2725@pendragon.ideasonboard.com>
Date: Fri, 2 Aug 2024 18:07:53 +0300
From: Laurent Pinchart <laurent.pinchart@...asonboard.com>
To: Daniel Vetter <daniel.vetter@...ll.ch>
Cc: Sakari Ailus <sakari.ailus@....fi>,
	Ricardo Ribalda Delgado <ricardo.ribalda@...il.com>,
	Dan Williams <dan.j.williams@...el.com>,
	James Bottomley <James.Bottomley@...senpartnership.com>,
	ksummit@...ts.linux.dev, linux-cxl@...r.kernel.org,
	linux-rdma@...r.kernel.org, netdev@...r.kernel.org, jgg@...dia.com
Subject: Re: [MAINTAINERS SUMMIT] Device Passthrough Considered Harmful?

On Wed, Jul 31, 2024 at 03:15:39PM +0200, Daniel Vetter wrote:
> On Wed, 31 Jul 2024 at 13:55, Sakari Ailus wrote:
> > This is also very different from GPUs or accel devices that are built to be
> > user-programmable. If I'd compare ISPs to different devices, then the
> > closest match would probably be video codecs -- which also use V4L2.
> 
> Really just aside, but I figured I should correct this. DRM supports
> plenty of video codecs. They're all tied to gpus, but the real reason
> really is that the hw has decent command submission support so that
> running the entire codec in userspace except the basic memory and
> batch execution and synchronization handling in the kernel is a
> feasible design. And actually good, because your kernel wont ever blow
> up trying to parse complex media formats because it just doesn't.

I don't think V4L2 codecs parse the bitstream in the kernel either, at
least not the recent ones.

-- 
Regards,

Laurent Pinchart