* [PATCH v4 1/4] drm: rework description of primary and cursor planes
@ 2020-12-11 18:46 Simon Ser
2020-12-11 18:46 ` [PATCH v4 2/4] drm: validate possible_crtcs for " Simon Ser
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: Simon Ser @ 2020-12-11 18:46 UTC (permalink / raw)
To: dri-devel; +Cc: Daniel Vetter, Pekka Paalanen
The previous wording could be understood by user-space evelopers as "a
primary/cursor plane is only compatible with a single CRTC" [1].
Reword the planes description to make it clear the DRM-internal
drm_crtc.primary and drm_crtc.cursor planes are for legacy uAPI.
[1]: https://github.com/swaywm/wlroots/pull/2333#discussion_r456788057
Signed-off-by: Simon Ser <contact@emersion.fr>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Pekka Paalanen <pekka.paalanen@collabora.com>
---
drivers/gpu/drm/drm_crtc.c | 3 +++
drivers/gpu/drm/drm_plane.c | 16 +++++++++-------
2 files changed, 12 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index 8d19d258547f..a6336c7154d6 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -256,6 +256,9 @@ struct dma_fence *drm_crtc_create_fence(struct drm_crtc *crtc)
* planes). For really simple hardware which has only 1 plane look at
* drm_simple_display_pipe_init() instead.
*
+ * The @primary and @cursor planes are only relevant for legacy uAPI, see
+ * &drm_crtc.primary and &drm_crtc.cursor.
+ *
* Returns:
* Zero on success, error code on failure.
*/
diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c
index 385801dd21f9..5d33ca9f0032 100644
--- a/drivers/gpu/drm/drm_plane.c
+++ b/drivers/gpu/drm/drm_plane.c
@@ -49,14 +49,16 @@
* &struct drm_plane (possibly as part of a larger structure) and registers it
* with a call to drm_universal_plane_init().
*
- * Cursor and overlay planes are optional. All drivers should provide one
- * primary plane per CRTC to avoid surprising userspace too much. See enum
- * drm_plane_type for a more in-depth discussion of these special uapi-relevant
- * plane types. Special planes are associated with their CRTC by calling
- * drm_crtc_init_with_planes().
- *
* The type of a plane is exposed in the immutable "type" enumeration property,
- * which has one of the following values: "Overlay", "Primary", "Cursor".
+ * which has one of the following values: "Overlay", "Primary", "Cursor" (see
+ * enum drm_plane_type). A plane can be compatible with multiple CRTCs, see
+ * &drm_plane.possible_crtcs.
+ *
+ * Legacy uAPI doesn't expose the primary and cursor planes directly. DRM core
+ * relies on the driver to set the primary and optionally the cursor plane used
+ * for legacy IOCTLs. This is done by calling drm_crtc_init_with_planes(). All
+ * drivers should provide one primary plane per CRTC to avoid surprising legacy
+ * userspace too much.
*/
static unsigned int drm_num_planes(struct drm_device *dev)
--
2.29.2
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^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH v4 2/4] drm: validate possible_crtcs for primary and cursor planes
2020-12-11 18:46 [PATCH v4 1/4] drm: rework description of primary and cursor planes Simon Ser
@ 2020-12-11 18:46 ` Simon Ser
2020-12-11 18:46 ` [PATCH v4 3/4] drm: require a non_NULL drm_crtc.primary Simon Ser
2020-12-11 18:46 ` [PATCH v4 4/4] drm: require each CRTC to have a unique primary plane Simon Ser
2 siblings, 0 replies; 4+ messages in thread
From: Simon Ser @ 2020-12-11 18:46 UTC (permalink / raw)
To: dri-devel; +Cc: Daniel Vetter, Pekka Paalanen
If a primary or cursor plane is not compatible with a CRTC it's attached
to via the legacy primary/cursor field, things will be broken for legacy
user-space.
v4: use drm_crtc_mask instead of BIT (Ville)
Signed-off-by: Simon Ser <contact@emersion.fr>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Pekka Paalanen <pekka.paalanen@collabora.com>
Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
---
drivers/gpu/drm/drm_mode_config.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/drivers/gpu/drm/drm_mode_config.c b/drivers/gpu/drm/drm_mode_config.c
index f1affc1bb679..1628c8b60d9a 100644
--- a/drivers/gpu/drm/drm_mode_config.c
+++ b/drivers/gpu/drm/drm_mode_config.c
@@ -625,6 +625,7 @@ static void validate_encoder_possible_crtcs(struct drm_encoder *encoder)
void drm_mode_config_validate(struct drm_device *dev)
{
struct drm_encoder *encoder;
+ struct drm_crtc *crtc;
if (!drm_core_check_feature(dev, DRIVER_MODESET))
return;
@@ -636,4 +637,19 @@ void drm_mode_config_validate(struct drm_device *dev)
validate_encoder_possible_clones(encoder);
validate_encoder_possible_crtcs(encoder);
}
+
+ drm_for_each_crtc(crtc, dev) {
+ if (crtc->primary) {
+ WARN(!(crtc->primary->possible_crtcs & drm_crtc_mask(crtc)),
+ "Bogus primary plane possible_crtcs: [PLANE:%d:%s] must be compatible with [CRTC:%d:%s]\n",
+ crtc->primary->base.id, crtc->primary->name,
+ crtc->base.id, crtc->name);
+ }
+ if (crtc->cursor) {
+ WARN(!(crtc->cursor->possible_crtcs & drm_crtc_mask(crtc)),
+ "Bogus cursor plane possible_crtcs: [PLANE:%d:%s] must be compatible with [CRTC:%d:%s]\n",
+ crtc->cursor->base.id, crtc->cursor->name,
+ crtc->base.id, crtc->name);
+ }
+ }
}
--
2.29.2
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^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH v4 3/4] drm: require a non_NULL drm_crtc.primary
2020-12-11 18:46 [PATCH v4 1/4] drm: rework description of primary and cursor planes Simon Ser
2020-12-11 18:46 ` [PATCH v4 2/4] drm: validate possible_crtcs for " Simon Ser
@ 2020-12-11 18:46 ` Simon Ser
2020-12-11 18:46 ` [PATCH v4 4/4] drm: require each CRTC to have a unique primary plane Simon Ser
2 siblings, 0 replies; 4+ messages in thread
From: Simon Ser @ 2020-12-11 18:46 UTC (permalink / raw)
To: dri-devel; +Cc: Daniel Vetter, Pekka Paalanen
If a CRTC is missing a legacy primary plane pointer, a lot of things
will be broken for user-space: fbdev stops working and the entire legacy
uAPI stops working.
Require all drivers to populate drm_crtc.primary to prevent these
issues. Warn if it's NULL.
Signed-off-by: Simon Ser <contact@emersion.fr>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Pekka Paalanen <pekka.paalanen@collabora.com>
---
drivers/gpu/drm/drm_mode_config.c | 3 +++
drivers/gpu/drm/drm_plane.c | 2 +-
2 files changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/drm_mode_config.c b/drivers/gpu/drm/drm_mode_config.c
index 1628c8b60d9a..1e5da83fd2a8 100644
--- a/drivers/gpu/drm/drm_mode_config.c
+++ b/drivers/gpu/drm/drm_mode_config.c
@@ -639,6 +639,9 @@ void drm_mode_config_validate(struct drm_device *dev)
}
drm_for_each_crtc(crtc, dev) {
+ WARN(!crtc->primary, "Missing primary plane on [CRTC:%d:%s]\n",
+ crtc->base.id, crtc->name);
+
if (crtc->primary) {
WARN(!(crtc->primary->possible_crtcs & drm_crtc_mask(crtc)),
"Bogus primary plane possible_crtcs: [PLANE:%d:%s] must be compatible with [CRTC:%d:%s]\n",
diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c
index 5d33ca9f0032..49b0a8b9ac02 100644
--- a/drivers/gpu/drm/drm_plane.c
+++ b/drivers/gpu/drm/drm_plane.c
@@ -57,7 +57,7 @@
* Legacy uAPI doesn't expose the primary and cursor planes directly. DRM core
* relies on the driver to set the primary and optionally the cursor plane used
* for legacy IOCTLs. This is done by calling drm_crtc_init_with_planes(). All
- * drivers should provide one primary plane per CRTC to avoid surprising legacy
+ * drivers must provide one primary plane per CRTC to avoid surprising legacy
* userspace too much.
*/
--
2.29.2
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^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH v4 4/4] drm: require each CRTC to have a unique primary plane
2020-12-11 18:46 [PATCH v4 1/4] drm: rework description of primary and cursor planes Simon Ser
2020-12-11 18:46 ` [PATCH v4 2/4] drm: validate possible_crtcs for " Simon Ser
2020-12-11 18:46 ` [PATCH v4 3/4] drm: require a non_NULL drm_crtc.primary Simon Ser
@ 2020-12-11 18:46 ` Simon Ser
2 siblings, 0 replies; 4+ messages in thread
From: Simon Ser @ 2020-12-11 18:46 UTC (permalink / raw)
To: dri-devel
User-space expects to be able to pick a primary plane for each CRTC
exposed by the driver. Make sure this assumption holds in
drm_mode_config_validate.
Use the legacy drm_crtc.primary field to check this, because it's
simpler and we require drivers to set it anyways. Accumulate a set of
primary planes which are already used for a CRTC in a bitmask. Error out
if a primary plane is re-used.
v2: new patch
v3:
- Use u64 instead of __u64 (Jani)
- Use `unsigned int` instead of `unsigned` (Jani)
v4:
- Use u32 instead of u64 for plane mask (Ville)
- Use drm_plane_mask instead of BIT (Ville)
- Fix typos (Ville)
Signed-off-by: Simon Ser <contact@emersion.fr>
Reviewed-by: Daniel Vetter <daniel@ffwll.ch>
Cc: Pekka Paalanen <ppaalanen@gmail.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
---
drivers/gpu/drm/drm_mode_config.c | 21 +++++++++++++++++++++
drivers/gpu/drm/drm_plane.c | 6 ++++++
2 files changed, 27 insertions(+)
diff --git a/drivers/gpu/drm/drm_mode_config.c b/drivers/gpu/drm/drm_mode_config.c
index 1e5da83fd2a8..7ffc0d6a8e2c 100644
--- a/drivers/gpu/drm/drm_mode_config.c
+++ b/drivers/gpu/drm/drm_mode_config.c
@@ -626,6 +626,9 @@ void drm_mode_config_validate(struct drm_device *dev)
{
struct drm_encoder *encoder;
struct drm_crtc *crtc;
+ struct drm_plane *plane;
+ u32 primary_with_crtc = 0, cursor_with_crtc = 0;
+ unsigned int num_primary = 0;
if (!drm_core_check_feature(dev, DRIVER_MODESET))
return;
@@ -647,12 +650,30 @@ void drm_mode_config_validate(struct drm_device *dev)
"Bogus primary plane possible_crtcs: [PLANE:%d:%s] must be compatible with [CRTC:%d:%s]\n",
crtc->primary->base.id, crtc->primary->name,
crtc->base.id, crtc->name);
+ WARN(primary_with_crtc & drm_plane_mask(crtc->primary),
+ "Primary plane [PLANE:%d:%s] used for multiple CRTCs",
+ crtc->primary->base.id, crtc->primary->name);
+ primary_with_crtc |= drm_plane_mask(crtc->primary);
}
if (crtc->cursor) {
WARN(!(crtc->cursor->possible_crtcs & drm_crtc_mask(crtc)),
"Bogus cursor plane possible_crtcs: [PLANE:%d:%s] must be compatible with [CRTC:%d:%s]\n",
crtc->cursor->base.id, crtc->cursor->name,
crtc->base.id, crtc->name);
+ WARN(cursor_with_crtc & drm_plane_mask(crtc->cursor),
+ "Cursor plane [PLANE:%d:%s] used for multiple CRTCs",
+ crtc->cursor->base.id, crtc->cursor->name);
+ cursor_with_crtc |= drm_plane_mask(crtc->cursor);
}
}
+
+ drm_for_each_plane(plane, dev) {
+ if (plane->type == DRM_PLANE_TYPE_PRIMARY) {
+ num_primary++;
+ }
+ }
+
+ WARN(num_primary != dev->mode_config.num_crtc,
+ "Must have as many primary planes as there are CRTCs, but have %u primary planes and %u CRTCs",
+ num_primary, dev->mode_config.num_crtc);
}
diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c
index 49b0a8b9ac02..a1f4510efa83 100644
--- a/drivers/gpu/drm/drm_plane.c
+++ b/drivers/gpu/drm/drm_plane.c
@@ -54,6 +54,12 @@
* enum drm_plane_type). A plane can be compatible with multiple CRTCs, see
* &drm_plane.possible_crtcs.
*
+ * Each CRTC must have a unique primary plane userspace can attach to enable
+ * the CRTC. In other words, userspace must be able to attach a different
+ * primary plane to each CRTC at the same time. Primary planes can still be
+ * compatible with multiple CRTCs. There must be exactly as many primary planes
+ * as there are CRTCs.
+ *
* Legacy uAPI doesn't expose the primary and cursor planes directly. DRM core
* relies on the driver to set the primary and optionally the cursor plane used
* for legacy IOCTLs. This is done by calling drm_crtc_init_with_planes(). All
--
2.29.2
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2020-12-11 18:46 [PATCH v4 1/4] drm: rework description of primary and cursor planes Simon Ser
2020-12-11 18:46 ` [PATCH v4 2/4] drm: validate possible_crtcs for " Simon Ser
2020-12-11 18:46 ` [PATCH v4 3/4] drm: require a non_NULL drm_crtc.primary Simon Ser
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