linux-kernel - Re: [git pull] habanalabs pull request for kernel 5.15

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Message-ID: <CAKMK7uHP1ii7c8eM=MddqHikaP+DS-2Rj6gxMp6eBxhWqqe52w@mail.gmail.com>
Date:   Fri, 20 Aug 2021 08:43:09 +0200
From:   Daniel Vetter <daniel.vetter@...ll.ch>
To:     Dave Airlie <airlied@...il.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jason Gunthorpe <jgg@...lanox.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Oded Gabbay <ogabbay@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [git pull] habanalabs pull request for kernel 5.15

On Thu, Aug 19, 2021 at 8:48 PM Dave Airlie <airlied@...il.com> wrote:
> On Fri, 20 Aug 2021 at 03:07, Greg KH <gregkh@...uxfoundation.org> wrote:
> >
> > On Thu, Aug 19, 2021 at 02:02:09PM +0300, Oded Gabbay wrote:
> > > Hi Greg,
> > >
> > > This is habanalabs pull request for the merge window of kernel 5.15.
> > > The commits divide roughly 50/50 between adding new features, such
> > > as peer-to-peer support with DMA-BUF or signaling from within a graph,
> > > and fixing various bugs, small improvements, etc.
> >
> > Pulled and pushed out, thanks!
>
> NAK for adding dma-buf or p2p support to this driver in the upstream
> kernel. There needs to be a hard line between
> "I-can't-believe-its-not-a-drm-driver" drivers which bypass our
> userspace requirements, and I consider this the line.
>
> This driver was merged into misc on the grounds it wasn't really a
> drm/gpu driver and so didn't have to accept our userspace rules.
>
> Adding dma-buf/p2p support to this driver is showing it really fits
> the gpu driver model and should be under the drivers/gpu rules since
> what are most GPUs except accelerators.
>
> We are opening a major can of worms (some would say merging habanalabs
> driver opened it), but this places us in the situation that if a GPU
> vendor just claims their hw is a "vector" accelerator they can use
> Greg to bypass all the work that been done to ensure we have
> maintainability long term. I don't want drivers in the tree using
> dma-buf to interact with other drivers when we don't have access to a
> userspace project to validate the kernel driver assumptions.

I think everything that can be said has been said over the last few
years, here on m-l and at plumbers, so just for the record my +1.

There's no point in negotiation for years with accel companies in the
background if the guy next door just gleefully offers to get pulled
over the table, no questions asked.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch