Commit d60ea31a authored by Sean Paul's avatar Sean Paul
Browse files

drm/TODO: Add drm_display_mode.hsync/vrefresh removal 



Drivers shouldn't be using these values, add a TODO so someone removes
them.

Changes in v2:
- Add drm_display_mode.vrefresh removal (Ville)
- Add Sam's R-b and bonus points
Changes in v3:
- Add hsync removal todo item (Daniel)
- Change vrefresh wording to make removal less optional

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Suggested-by: default avatarDaniel Vetter <daniel@ffwll.ch>
Reviewed-by: default avatarDaniel Vetter <daniel@ffwll.ch>
Reviewed-by: default avatarSam Ravnborg <sam@ravnborg.org>
Bonus-points-awarded-by: default avatarSam Ravnborg <sam@ravnborg.org>
Signed-off-by: default avatarSean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20190129192637.73296-1-sean@poorly.run
parent 3dadbd29

Documentation/gpu/todo.rst

+28 −0
Original line number Diff line number Diff line
@@ -272,6 +272,34 @@ no one knows what that means) since underneath they just use dma_alloc_coherent. 


Contact: Laurent Pinchart, Daniel Vetter



Convert direct mode.vrefresh accesses to use drm_mode_vrefresh()

----------------------------------------------------------------



drm_display_mode.vrefresh isn't guaranteed to be populated. As such, using it

is risky and has been known to cause div-by-zero bugs. Fortunately, drm core

has helper which will use mode.vrefresh if it's !0 and will calculate it from

the timings when it's 0.



Use simple search/replace, or (more fun) cocci to replace instances of direct

vrefresh access with a call to the helper. Check out

https://lists.freedesktop.org/archives/dri-devel/2019-January/205186.html for

inspiration.



Once all instances of vrefresh have been converted, remove vrefresh from

drm_display_mode to avoid future use.



Contact: Sean Paul



Remove drm_display_mode.hsync

-----------------------------



We have drm_mode_hsync() to calculate this from hsync_start/end, since drivers

shouldn't/don't use this, remove this member to avoid any temptations to use it

in the future. If there is any debug code using drm_display_mode.hsync, convert

it to use drm_mode_hsync() instead.



Contact: Sean Paul



Core refactorings

=================

CRA Git | Maintained and supported by SUSTech CRA and CCSE