diff options
| author | Ville Syrjälä <ville.syrjala@linux.intel.com> | 2016-11-03 16:10:01 +0200 |
|---|---|---|
| committer | Daniel Vetter <daniel.vetter@ffwll.ch> | 2016-11-08 11:10:45 +0100 |
| commit | 91d5ee0451607d2a33c2b811ef3cc4a3e4578ed8 (patch) | |
| tree | d8812578a725bdb290a73cbfc2b5b7f390fa5416 /include | |
| parent | e587803c0a0f6bc6e1a9c4761310f96f7bc49acb (diff) | |
drm/uapi: Add a warning that mode flags must match the xrandr definitions
Existing userspace expected the mode flags to match the xrandr
definitions 1:1, and even adding new flags in he previously unused
bits is likely to break existing userspace. Add a comment warning
people about this potential trap.
Cc: Shashank Sharma <shashank.sharma@intel.com>
Cc: "Lin, Jia" <lin.a.jia@intel.com>
Cc: Akashdeep Sharma <akashdeep.sharma@intel.com>
Cc: Jim Bride <jim.bride@linux.intel.com>
Cc: Jose Abreu <Jose.Abreu@synopsys.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Emil Velikov <emil.l.velikov@gmail.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1478182201-26086-1-git-send-email-ville.syrjala@linux.intel.com
Diffstat (limited to 'include')
| -rw-r--r-- | include/uapi/drm/drm_mode.h | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h index 084b50a02dc5..01000c9f7c2c 100644 --- a/include/uapi/drm/drm_mode.h +++ b/include/uapi/drm/drm_mode.h @@ -47,7 +47,15 @@ extern "C" { #define DRM_MODE_TYPE_DRIVER (1<<6) /* Video mode flags */ -/* bit compatible with the xorg definitions. */ +/* bit compatible with the xrandr RR_ definitions (bits 0-13) + * + * ABI warning: Existing userspace really expects + * the mode flags to match the xrandr definitions. Any + * changes that don't match the xrandr definitions will + * likely need a new client cap or some other mechanism + * to avoid breaking existing userspace. This includes + * allocating new flags in the previously unused bits! + */ #define DRM_MODE_FLAG_PHSYNC (1<<0) #define DRM_MODE_FLAG_NHSYNC (1<<1) #define DRM_MODE_FLAG_PVSYNC (1<<2) |