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Date: Wed, 25 Mar 2015 10:00:25 +1000
Message-ID: <CAPM=9tyM9AxX-RHhbO-LK+LTyQC6YjwW67pZM1XjbL35+counA@mail.gmail.com>
Subject: Re: [PATCH] Add virtio gpu driver.
From: Dave Airlie <airlied@gmail.com>
To: Daniel Stone <daniel@fooishbar.org>
Cc: Gerd Hoffmann <kraxel@redhat.com>, virtio-dev@lists.oasis-open.org,
        "Michael S. Tsirkin" <mst@redhat.com>,
        "open list:ABI/API" <linux-api@vger.kernel.org>,
        Rusty Russell <rusty@rustcorp.com.au>,
        open list <linux-kernel@vger.kernel.org>,
        "open list:DRM DRIVERS" <dri-devel@lists.freedesktop.org>,
        "open list:VIRTIO CORE, NET..." 
	<virtualization@lists.linux-foundation.org>,
        Dave Airlie <airlied@redhat.com>
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On 25 March 2015 at 08:50, Daniel Stone <daniel@fooishbar.org> wrote:
> Hi,
>
> On 24 March 2015 at 16:07, Gerd Hoffmann <kraxel@redhat.com> wrote:
>> +static int virtio_gpu_crtc_page_flip(struct drm_crtc *crtc,
>> +                                    struct drm_framebuffer *fb,
>> +                                    struct drm_pending_vblank_event *event,
>> +                                    uint32_t flags)
>> +{
>> +       return -EINVAL;
>> +}
>
> I'm not going to lie, I was really hoping the 5th (?) GPU option for
> Qemu would support pageflipping. Daniel's comment about conversion to
> atomic is relevant, but: do you have a mechanism which allows you to
> post updates (e.g. 'start displaying this buffer now please') that
> allows you to get events back when they have actually been displayed?

Page flip is implemented in a later patch,

https://www.kraxel.org/cgit/linux/commit/?h=virtio-gpu&id=1e167e8e964f8e08100d315dd354cc0a4b090841

Since its a long way from an actual display, finding out when
something is actually displayed is hard,
but when we've posted it to the frontbuffer should be fine.

Dave.