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drm/doc: Discourage usage of MODESET_CTL ioctl

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Leftover from the old days of ums and should be used any longer. Since

commit 29935554b3
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.

v2: Fix up mangled sentence spotted by Michel.

Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Michel Dänzer <michel@daenzer.net>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Daniel Vetter 2014-05-08 15:39:19 +02:00
parent add1d00823
commit 8edffbb933
1 changed files with 6 additions and 6 deletions
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12
Documentation/DocBook/drm.tmpl
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@ -2861,12 +2861,12 @@ 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 counter is reset to 0 at some point during modeset. Modern
drivers should not call this any more since with kernel mode
setting it is a no-op.
</para>
</listitem>
</varlistentry>