From d60ea31a87314eb7bea0b2dcbd36cf12bdf9ac0d Mon Sep 17 00:00:00 2001 From: Sean Paul Date: Tue, 29 Jan 2019 14:26:29 -0500 Subject: [PATCH] drm/TODO: Add drm_display_mode.hsync/vrefresh removal MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 Suggested-by: Daniel Vetter Reviewed-by: Daniel Vetter Reviewed-by: Sam Ravnborg Bonus-points-awarded-by: Sam Ravnborg Signed-off-by: Sean Paul Link: https://patchwork.freedesktop.org/patch/msgid/20190129192637.73296-1-sean@poorly.run --- Documentation/gpu/todo.rst | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) diff --git a/Documentation/gpu/todo.rst b/Documentation/gpu/todo.rst index a1d91ca7f65c..cda4a37a02f0 100644 --- a/Documentation/gpu/todo.rst +++ b/Documentation/gpu/todo.rst @@ -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 ================= -- 2.39.5