[PATCH] [RFC] drm: Nerf DRM_CONTROL nodes

[Thomas Hellstrom]

Hi!

This patch breaks the vmwgfx resolutionKMS daemon which opens a control
node to tell DRM about the monitor layout...

/Thomas


On 10/28/2016 10:10 AM, Daniel Vetter wrote:
> Looking at the ioctl permission checks I noticed that it's impossible
> to import gem buffers into a control nodes, and fd2handle/handle2fd
> also don't work, so no joy with dma-bufs.
>
> The only way to do anything with a control node is by drawing stuff
> into a dumb buffer and displaying that. I suspect control nodes are an
> entirely unused thing, and a cursory check shows that there does not
> seem to be any callers of drmOpenControl nor of the other drmOpen
> functions using DRM_MODE_CONTROL.
>
> Since I don't like dead uabi, let's remove it. But since this would be
> a really big change I think it's better to start out small by simply
> not registering anything. We can garbage-collect the dead code later
> on, once we're sure it's really not used anywhere.
>
> Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
> ---
>  drivers/gpu/drm/drm_drv.c | 6 ------
>  1 file changed, 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
> index 6efdba4993fc..f085e28ffc6f 100644
> --- a/drivers/gpu/drm/drm_drv.c
> +++ b/drivers/gpu/drm/drm_drv.c
> @@ -517,12 +517,6 @@ int drm_dev_init(struct drm_device *dev,
>  		goto err_free;
>  	}
>  
> -	if (drm_core_check_feature(dev, DRIVER_MODESET)) {
> -		ret = drm_minor_alloc(dev, DRM_MINOR_CONTROL);
> -		if (ret)
> -			goto err_minors;
> -	}
> -
>  	if (drm_core_check_feature(dev, DRIVER_RENDER)) {
>  		ret = drm_minor_alloc(dev, DRM_MINOR_RENDER);
>  		if (ret)