linux-kernel - Re: [PATCH v2 2/2] drm/qxl: kick out vgacon

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Date:   Thu, 21 Feb 2019 13:20:11 +0100
From:   Daniel Vetter <daniel@...ll.ch>
To:     Gerd Hoffmann <kraxel@...hat.com>
Cc:     dri-devel@...ts.freedesktop.org, daniel@...ll.ch,
        Dave Airlie <airlied@...hat.com>,
        David Airlie <airlied@...ux.ie>,
        "open list:DRM DRIVER FOR QXL VIRTUAL GPU" 
        <virtualization@...ts.linux-foundation.org>,
        "open list:DRM DRIVER FOR QXL VIRTUAL GPU" 
        <spice-devel@...ts.freedesktop.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/2] drm/qxl: kick out vgacon

On Thu, Feb 21, 2019 at 12:35:34PM +0100, Gerd Hoffmann wrote:
> Problem:  qxl switches from native mode back into vga compatibility mode
> when it notices someone is accessing vga registers.  And vgacon does
> exactly that before fbcon takes over.  So make sure we kick out vgacon
> early enough that it wouldn't disturb us.
> 
> Signed-off-by: Gerd Hoffmann <kraxel@...hat.com>
> ---
>  drivers/gpu/drm/qxl/qxl_drv.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/gpu/drm/qxl/qxl_drv.c b/drivers/gpu/drm/qxl/qxl_drv.c
> index bb81e310eb..08446561aa 100644
> --- a/drivers/gpu/drm/qxl/qxl_drv.c
> +++ b/drivers/gpu/drm/qxl/qxl_drv.c
> @@ -95,6 +95,7 @@ qxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
>  		goto modeset_cleanup;
>  
>  	drm_fb_helper_remove_conflicting_pci_framebuffers(pdev, 0, "qxl");
> +	drm_fb_helper_kick_out_vgacon();

I was thinking of checking whether pdev is a VGA class device and whether
it decodes vga access, and in that case automatically calling
kick_out_vgacon from remove_conflicting_pci_framebuffer. Since that's what
drivers want anyway, and those who don't can open code it.

Or is there an issue with that?
-Daniel

>  	drm_fbdev_generic_setup(&qdev->ddev, 32);
>  	return 0;
>  
> -- 
> 2.9.3
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch