linux-kernel - [PATCH 1/6] drm/atomic-helper: document drm_atomic_helper

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20241222-drm-dirty-modeset-v1-1-0e76a53eceb9@linaro.org>
Date: Sun, 22 Dec 2024 07:00:41 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, 
 Rob Clark <robdclark@...il.com>, Abhinav Kumar <quic_abhinavk@...cinc.com>, 
 Sean Paul <sean@...rly.run>, Marijn Suijten <marijn.suijten@...ainline.org>, 
 Chandan Uddaraju <chandanu@...eaurora.org>, 
 Jeykumar Sankaran <jsanka@...eaurora.org>, 
 Jordan Crouse <jordan@...micpenguin.net>, 
 Sravanthi Kollukuduru <skolluku@...eaurora.org>
Cc: dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org, 
 Archit Taneja <architt@...eaurora.org>, 
 Rajesh Yadav <ryadav@...eaurora.org>, linux-arm-msm@...r.kernel.org, 
 freedreno@...ts.freedesktop.org, Simona Vetter <simona.vetter@...ll.ch>
Subject: [PATCH 1/6] drm/atomic-helper: document drm_atomic_helper_check()
 restrictions

The drm_atomic_helper_check() calls drm_atomic_helper_check_modeset()
insternally. Document that corresponding restrictions also apply to the
drivers that call the former function (as it's easy to miss the
documentation for the latter function).

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
---
 drivers/gpu/drm/drm_atomic_helper.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index 5186d2114a503701e228e382cc45180b0c578d0c..f26887c3fe8b194137200f9f2426653274c50fda 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -1059,6 +1059,15 @@ EXPORT_SYMBOL(drm_atomic_helper_check_planes);
  * For example enable/disable of a cursor plane which have fixed zpos value
  * would trigger all other enabled planes to be forced to the state change.
  *
+ * IMPORTANT:
+ *
+ * As this function calls drm_atomic_helper_check_modeset() internally, its
+ * restrictions also apply:
+ * Drivers which set &drm_crtc_state.mode_changed (e.g. in their
+ * &drm_plane_helper_funcs.atomic_check hooks if a plane update can't be done
+ * without a full modeset) _must_ call drm_atomic_helper_check_modeset()
+ * function again after that change.
+ *
  * RETURNS:
  * Zero for success or -errno
  */

-- 
2.39.5