Re: [PATCH 06/12] drm/doc: Discourage usage of MODESET_CTL ioctl

["Michel Dänzer" <michel@daenzer.net>]

On 15.05.2014 03:51, Daniel Vetter wrote:
> Leftover from the old days of ums and should be used any longer. Since
> 
> commit 29935554b384b1b3a7377d6f0b03b21d18a61683
> Author: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Date:   Wed May 30 00:58:09 2012 +0200
> 
>     drm: Disallow DRM_IOCTL_MODESET_CTL for KMS drivers
> 
> it is a complete no-Op for kms drivers.
> 
> Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> ---
>  Documentation/DocBook/drm.tmpl | 11 +++++------
>  1 file changed, 5 insertions(+), 6 deletions(-)
> 
> diff --git a/Documentation/DocBook/drm.tmpl b/Documentation/DocBook/drm.tmpl
> index 83dd0b043c28..e37a77a72b8b 100644
> --- a/Documentation/DocBook/drm.tmpl
> +++ b/Documentation/DocBook/drm.tmpl
> @@ -2861,12 +2861,11 @@ int num_ioctls;</synopsis>
>              <term>DRM_IOCTL_MODESET_CTL</term>
>              <listitem>
>                <para>
> -                This should be called by application level drivers before and
> -                after mode setting, since on many devices the vertical blank
> -                counter is reset at that time.  Internally, the DRM snapshots
> -                the last vblank count when the ioctl is called with the
> -                _DRM_PRE_MODESET command, so that the counter won't go backwards
> -                (which is dealt with when _DRM_POST_MODESET is used).
> +		This was only used for user-mode-settind drivers around
> +		modesetting changes to allow the kernel to update the vblank
> +		interrupt after mode setting, since on many devices the vertical
> +		blank.

This sentence looks mangled pretty badly. Did you have something like
this in mind?

"This was only used for user-mode-setting drivers around modesetting
changes to allow the kernel to keep the vertical blank counters
consistent, since on many devices the hardware vertical blank counter is
reset to 0 at some point during modeset changes."


-- 
Earthling Michel Dänzer            |                  http://www.amd.com
Libre software enthusiast          |                Mesa and X developer