linux-kernel - [PATCH v4 1/5] drm: Allow drivers to indicate the damage helpers to ignore damage clips

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Message-ID: <20231123221315.3579454-2-javierm@redhat.com>
Date:   Thu, 23 Nov 2023 23:13:00 +0100
From:   Javier Martinez Canillas <javierm@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     Maxime Ripard <mripard@...nel.org>, Zack Rusin <zackr@...are.com>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Pekka Paalanen <pekka.paalanen@...labora.com>,
        Bilal Elmoussaoui <belmouss@...hat.com>,
        Simon Ser <contact@...rsion.fr>,
        Erico Nunes <nunes.erico@...il.com>,
        Sima Vetter <daniel.vetter@...ll.ch>,
        Javier Martinez Canillas <javierm@...hat.com>,
        stable@...r.kernel.org,
        nerdopolis <bluescreen_avenger@...izon.net>,
        Daniel Vetter <daniel@...ll.ch>,
        David Airlie <airlied@...il.com>,
        Gerd Hoffmann <kraxel@...hat.com>,
        Jonathan Corbet <corbet@....net>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        dri-devel@...ts.freedesktop.org, linux-doc@...r.kernel.org
Subject: [PATCH v4 1/5] drm: Allow drivers to indicate the damage helpers to ignore damage clips

It allows drivers to set a struct drm_plane_state .ignore_damage_clips in
their plane's .atomic_check callback, as an indication to damage helpers
such as drm_atomic_helper_damage_iter_init() that the damage clips should
be ignored.

To be used by drivers that do per-buffer (e.g: virtio-gpu) uploads (rather
than per-plane uploads), since these type of drivers need to handle buffer
damages instead of frame damages.

That way, these drivers could force a full plane update if the framebuffer
attached to a plane's state has changed since the last update (page-flip).

Fixes: 01f05940a9a7 ("drm/virtio: Enable fb damage clips property for the primary plane")
Cc: <stable@...r.kernel.org> # v6.4+
Reported-by: nerdopolis <bluescreen_avenger@...izon.net>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218115
Suggested-by: Thomas Zimmermann <tzimmermann@...e.de>
Signed-off-by: Javier Martinez Canillas <javierm@...hat.com>
Reviewed-by: Thomas Zimmermann <tzimmermann@...e.de>
Reviewed-by: Zack Rusin <zackr@...are.com>
Acked-by: Sima Vetter <daniel.vetter@...ll.ch>
---

Changes in v4:
- Refer in ignore_damage_clips kernel-doc to "Damage Tracking Properties"
  KMS documentation section (Sima Vetter).

Changes in v2:
- Add a struct drm_plane_state .ignore_damage_clips to set in the plane's
  .atomic_check, instead of having different helpers (Thomas Zimmermann).

 Documentation/gpu/drm-kms.rst       |  2 ++
 drivers/gpu/drm/drm_damage_helper.c |  3 ++-
 include/drm/drm_plane.h             | 10 ++++++++++
 3 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/Documentation/gpu/drm-kms.rst b/Documentation/gpu/drm-kms.rst
index 270d320407c7..a98a7e04e86f 100644
--- a/Documentation/gpu/drm-kms.rst
+++ b/Documentation/gpu/drm-kms.rst
@@ -548,6 +548,8 @@ Plane Composition Properties
 .. kernel-doc:: drivers/gpu/drm/drm_blend.c
    :doc: overview
 
+.. _damage_tracking_properties:
+
 Damage Tracking Properties
 --------------------------
 
diff --git a/drivers/gpu/drm/drm_damage_helper.c b/drivers/gpu/drm/drm_damage_helper.c
index d8b2955e88fd..afb02aae707b 100644
--- a/drivers/gpu/drm/drm_damage_helper.c
+++ b/drivers/gpu/drm/drm_damage_helper.c
@@ -241,7 +241,8 @@ drm_atomic_helper_damage_iter_init(struct drm_atomic_helper_damage_iter *iter,
 	iter->plane_src.x2 = (src.x2 >> 16) + !!(src.x2 & 0xFFFF);
 	iter->plane_src.y2 = (src.y2 >> 16) + !!(src.y2 & 0xFFFF);
 
-	if (!iter->clips || !drm_rect_equals(&state->src, &old_state->src)) {
+	if (!iter->clips || state->ignore_damage_clips ||
+	    !drm_rect_equals(&state->src, &old_state->src)) {
 		iter->clips = NULL;
 		iter->num_clips = 0;
 		iter->full_update = true;
diff --git a/include/drm/drm_plane.h b/include/drm/drm_plane.h
index 79d62856defb..fef775200a81 100644
--- a/include/drm/drm_plane.h
+++ b/include/drm/drm_plane.h
@@ -190,6 +190,16 @@ struct drm_plane_state {
 	 */
 	struct drm_property_blob *fb_damage_clips;
 
+	/**
+	 * @ignore_damage_clips:
+	 *
+	 * Set by drivers to indicate the drm_atomic_helper_damage_iter_init()
+	 * helper that the @fb_damage_clips blob property should be ignored.
+	 *
+	 * See :ref:`damage_tracking_properties` for more information.
+	 */
+	bool ignore_damage_clips;
+
 	/**
 	 * @src:
 	 *
-- 
2.41.0