linux-kernel - Re: [PATCH 3/3] misc/habalabs: don't set default fence

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Message-ID: <CAFCwf10m14ModSuRbQAsWf5CSJvTeP7YRzcokD=o+m2Pa0TqKg@mail.gmail.com>
Date:   Mon, 11 May 2020 12:36:17 +0300
From:   Oded Gabbay <oded.gabbay@...il.com>
To:     Daniel Vetter <daniel.vetter@...ll.ch>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        DRI Development <dri-devel@...ts.freedesktop.org>,
        Intel Graphics Development <intel-gfx@...ts.freedesktop.org>,
        Daniel Vetter <daniel.vetter@...el.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Olof Johansson <olof@...om.net>,
        Sumit Semwal <sumit.semwal@...aro.org>,
        linux-media@...r.kernel.org, linaro-mm-sig@...ts.linaro.org
Subject: Re: [PATCH 3/3] misc/habalabs: don't set default fence_ops->wait

On Mon, May 11, 2020 at 12:11 PM Daniel Vetter <daniel.vetter@...ll.ch> wrote:
>
> It's the default.
Thanks for catching that.

>
> Also so much for "we're not going to tell the graphics people how to
> review their code", dma_fence is a pretty core piece of gpu driver
> infrastructure. And it's very much uapi relevant, including piles of
> corresponding userspace protocols and libraries for how to pass these
> around.
>
> Would be great if habanalabs would not use this (from a quick look
> it's not needed at all), since open source the userspace and playing
> by the usual rules isn't on the table. If that's not possible (because
> it's actually using the uapi part of dma_fence to interact with gpu
> drivers) then we have exactly what everyone promised we'd want to
> avoid.

We don't use the uapi parts, we currently only using the fencing and
signaling ability of this module inside our kernel code. But maybe I
didn't understand what you request. You want us *not* to use this
well-written piece of kernel code because it is only used by graphics
drivers ?
I'm sorry but I don't get this argument, if this is indeed what you meant.

Oded

>
> Signed-off-by: Daniel Vetter <daniel.vetter@...el.com>
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Cc:     Olof Johansson <olof@...om.net>
> Cc: Oded Gabbay <oded.gabbay@...il.com>
> Cc: Sumit Semwal <sumit.semwal@...aro.org>
> Cc: linux-media@...r.kernel.org
> Cc: linaro-mm-sig@...ts.linaro.org
> ---
>  drivers/misc/habanalabs/command_submission.c | 1 -
>  1 file changed, 1 deletion(-)
>
> diff --git a/drivers/misc/habanalabs/command_submission.c b/drivers/misc/habanalabs/command_submission.c
> index 409276b6374d..cc3ce759b6c3 100644
> --- a/drivers/misc/habanalabs/command_submission.c
> +++ b/drivers/misc/habanalabs/command_submission.c
> @@ -46,7 +46,6 @@ static const struct dma_fence_ops hl_fence_ops = {
>         .get_driver_name = hl_fence_get_driver_name,
>         .get_timeline_name = hl_fence_get_timeline_name,
>         .enable_signaling = hl_fence_enable_signaling,
> -       .wait = dma_fence_default_wait,
>         .release = hl_fence_release
>  };
>
> --
> 2.26.2
>