Re: [Qemu-devel] [PATCH v3 3/3] vfio/display: delay link up event

[Liam Merwick <liam.merwick@oracle.com>]

On 22/02/2019 05:49, Gerd Hoffmann wrote:
> Kick the display link up event with a 0.1 sec delay,
> so the guest has a chance to notice the link down first.
> 
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

Depending on your thoughts on the suggestion in patch 1 regarding a 
comment at the 'err' label - another candidate in 
vfio_display_edid_link_up().

Either way:

Reviewed-by: Liam Merwick <liam.merwick@oracle.com>


> ---
>   include/hw/vfio/vfio-common.h |  1 +
>   hw/vfio/display.c             | 26 +++++++++++++++++++++++---
>   2 files changed, 24 insertions(+), 3 deletions(-)
> 
> diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
> index 5f7f709b95f1..b65a2f051886 100644
> --- a/include/hw/vfio/vfio-common.h
> +++ b/include/hw/vfio/vfio-common.h
> @@ -151,6 +151,7 @@ typedef struct VFIODisplay {
>       struct vfio_region_info *edid_info;
>       struct vfio_region_gfx_edid *edid_regs;
>       uint8_t *edid_blob;
> +    QEMUTimer *edid_link_timer;
>       struct {
>           VFIORegion buffer;
>           DisplaySurface *surface;
> diff --git a/hw/vfio/display.c b/hw/vfio/display.c
> index 8bf7c890be96..971e801dc05c 100644
> --- a/hw/vfio/display.c
> +++ b/hw/vfio/display.c
> @@ -38,6 +38,21 @@
>           goto err;
>   
>   
> +static void vfio_display_edid_link_up(void *opaque)
> +{
> +    VFIOPCIDevice *vdev = opaque;
> +    VFIODisplay *dpy = vdev->dpy;
> +    int fd = vdev->vbasedev.fd;
> +
> +    dpy->edid_regs->link_state = VFIO_DEVICE_GFX_LINK_STATE_UP;
> +    pwrite_field(fd, dpy->edid_info, dpy->edid_regs, link_state);
> +    trace_vfio_display_edid_link_up();
> +    return;
> +
> +err:
> +    trace_vfio_display_edid_write_error();
> +}
> +
>   static void vfio_display_edid_update(VFIOPCIDevice *vdev, bool enabled,
>                                        int prefx, int prefy)
>   {
> @@ -50,6 +65,7 @@ static void vfio_display_edid_update(VFIOPCIDevice *vdev, bool enabled,
>           .prefy = prefy ?: vdev->display_yres,
>       };
>   
> +    timer_del(dpy->edid_link_timer);
>       dpy->edid_regs->link_state = VFIO_DEVICE_GFX_LINK_STATE_DOWN;
>       pwrite_field(fd, dpy->edid_info, dpy->edid_regs, link_state);
>       trace_vfio_display_edid_link_down();
> @@ -77,9 +93,8 @@ static void vfio_display_edid_update(VFIOPCIDevice *vdev, bool enabled,
>           goto err;
>       }
>   
> -    dpy->edid_regs->link_state = VFIO_DEVICE_GFX_LINK_STATE_UP;
> -    pwrite_field(fd, dpy->edid_info, dpy->edid_regs, link_state);
> -    trace_vfio_display_edid_link_up();
> +    timer_mod(dpy->edid_link_timer,
> +              qemu_clock_get_ms(QEMU_CLOCK_REALTIME) + 100);
>       return;
>   
>   err:
> @@ -136,6 +151,9 @@ static void vfio_display_edid_init(VFIOPCIDevice *vdev)
>           vdev->display_yres = dpy->edid_regs->max_yres;
>       }
>   
> +    dpy->edid_link_timer = timer_new_ms(QEMU_CLOCK_REALTIME,
> +                                        vfio_display_edid_link_up, vdev);
> +
>       vfio_display_edid_update(vdev, true, 0, 0);
>       return;
>   
> @@ -154,6 +172,8 @@ static void vfio_display_edid_exit(VFIODisplay *dpy)
>   
>       g_free(dpy->edid_regs);
>       g_free(dpy->edid_blob);
> +    timer_del(dpy->edid_link_timer);
> +    timer_free(dpy->edid_link_timer);
>   }
>   
>   static void vfio_display_update_cursor(VFIODMABuf *dmabuf,
>