[PATCH v3 0/2] drm/drm_blend: allow blend mode property without PREMULTI

[PATCH v3 0/2] drm/drm_blend: allow blend mode property without PREMULTI

[Leandro Ribeiro]

Some hardware only supports the COVERAGE blend mode and lacks PREMULTI
support entirely. DRM currently requires that PREMULTI is present when
creating a blend mode property, which prevents such drivers from being
properly upstreamed.

This series removes this restriction and allows drivers to create a blend
mode property without PREMULTI.

On Weston (userspace), we are working [1] towards adding support for
this kind of hardware.

[1] https://gitlab.freedesktop.org/wayland/weston/-/merge_requests/2046

v3:
- Changed where we enforce drivers to expose blend mode for planes that
  support the alpha property or pixel formats with alpha.
- Fixed missing check to forbid calling
  drm_plane_create_blend_mode_property() with a zero bitmask of
  supported modes.

v2:
- Force drivers to expose blend mode if plane supports alpha property
  or pixel format with alpha.

Leandro Ribeiro (2):
  drm/drm_blend: allow blend mode property without PREMULTI
  drm: ensure blend mode supported if alpha exposed

 drivers/gpu/drm/drm_blend.c         | 20 +++++++++++-----
 drivers/gpu/drm/drm_crtc_internal.h |  2 +-
 drivers/gpu/drm/drm_drv.c           |  7 ++++--
 drivers/gpu/drm/drm_mode_config.c   | 37 +++++++++++++++++++++++++++--
 4 files changed, 55 insertions(+), 11 deletions(-)

-- 
2.54.0

[PATCH v3 1/2] drm/drm_blend: allow blend mode property without PREMULTI

[Leandro Ribeiro]

Some hardware only supports the COVERAGE blend mode and lacks PREMULTI
support entirely. DRM currently requires that PREMULTI is present when
creating a blend mode property, which prevents such drivers from being
properly upstreamed.

Remove this restriction and allow drivers to create a blend mode
property without PREMULTI, enabling support for hardware that
implements only COVERAGE blend mode.

This does not introduce a regression, as no existing upstream drivers
expose only COVERAGE. However, userspace that wants to support such kind
of hardware in the future will have to check the supported blend modes
instead of assuming PREMULTI is always supported.

Signed-off-by: Leandro Ribeiro <leandro.ribeiro@collabora.com>
---
 drivers/gpu/drm/drm_blend.c | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/drm_blend.c b/drivers/gpu/drm/drm_blend.c
index 1f3af27d2418..7d4033989749 100644
--- a/drivers/gpu/drm/drm_blend.c
+++ b/drivers/gpu/drm/drm_blend.c
@@ -563,10 +563,10 @@ EXPORT_SYMBOL(drm_atomic_normalize_zpos);
 /**
  * drm_plane_create_blend_mode_property - create a new blend mode property
  * @plane: drm plane
- * @supported_modes: bitmask of supported modes, must include
- *		     BIT(DRM_MODE_BLEND_PREMULTI). Current DRM assumption is
- *		     that alpha is premultiplied, and old userspace can break if
- *		     the property defaults to anything else.
+ * @supported_modes: bitmask of supported modes. When
+ *		     BIT(DRM_MODE_BLEND_PREMULTI) is included, it will be used
+ *		     as the default. Otherwise, the default will fallback to one
+ *		     of the supported modes.
  *
  * This creates a new property describing the blend mode.
  *
@@ -599,13 +599,14 @@ int drm_plane_create_blend_mode_property(struct drm_plane *plane,
 		{ DRM_MODE_BLEND_PREMULTI, "Pre-multiplied" },
 		{ DRM_MODE_BLEND_COVERAGE, "Coverage" },
 	};
+	unsigned int default_mode;
 	unsigned int valid_mode_mask = BIT(DRM_MODE_BLEND_PIXEL_NONE) |
 				       BIT(DRM_MODE_BLEND_PREMULTI)   |
 				       BIT(DRM_MODE_BLEND_COVERAGE);
 	int i;
 
 	if (WARN_ON((supported_modes & ~valid_mode_mask) ||
-		    ((supported_modes & BIT(DRM_MODE_BLEND_PREMULTI)) == 0)))
+		    (supported_modes == 0)))
 		return -EINVAL;
 
 	prop = drm_property_create(dev, DRM_MODE_PROP_ENUM,
@@ -630,7 +631,14 @@ int drm_plane_create_blend_mode_property(struct drm_plane *plane,
 		}
 	}
 
-	drm_object_attach_property(&plane->base, prop, DRM_MODE_BLEND_PREMULTI);
+	if (supported_modes & BIT(DRM_MODE_BLEND_PREMULTI))
+		default_mode = DRM_MODE_BLEND_PREMULTI;
+	else if (supported_modes & BIT(DRM_MODE_BLEND_COVERAGE))
+		default_mode = DRM_MODE_BLEND_COVERAGE;
+	else
+		default_mode = DRM_MODE_BLEND_PIXEL_NONE;
+
+	drm_object_attach_property(&plane->base, prop, default_mode);
 	plane->blend_mode_property = prop;
 
 	return 0;
-- 
2.54.0

[PATCH v3 2/2] drm: ensure blend mode supported if alpha exposed

[Leandro Ribeiro]

Before "drm/drm_blend: allow blend mode property without PREMULTI",
userspace would have to assume that only PREMULTI was supported by
drivers that didn't expose the blend mode property. But now userspace
shouldn't relly on that, as they can't count with drivers always
supporting PREMULTI.

Error out if a driver expose alpha property or pixel formats with alpha
and does not expose the blend mode property. This way userspace don't
have to guess. Drivers that hit such error must be fixed.

Signed-off-by: Leandro Ribeiro <leandro.ribeiro@collabora.com>
---
 drivers/gpu/drm/drm_crtc_internal.h |  2 +-
 drivers/gpu/drm/drm_drv.c           |  7 ++++--
 drivers/gpu/drm/drm_mode_config.c   | 37 +++++++++++++++++++++++++++--
 3 files changed, 41 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/drm_crtc_internal.h b/drivers/gpu/drm/drm_crtc_internal.h
index c09409229644..2a4862202496 100644
--- a/drivers/gpu/drm/drm_crtc_internal.h
+++ b/drivers/gpu/drm/drm_crtc_internal.h
@@ -95,7 +95,7 @@ int drm_mode_setcrtc(struct drm_device *dev,
 /* drm_mode_config.c */
 int drm_modeset_register_all(struct drm_device *dev);
 void drm_modeset_unregister_all(struct drm_device *dev);
-void drm_mode_config_validate(struct drm_device *dev);
+int drm_mode_config_validate(struct drm_device *dev);
 
 /* drm_modes.c */
 const char *drm_get_mode_status_name(enum drm_mode_status status);
diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index 985c283cf59f..def78046a963 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -1059,8 +1059,11 @@ int drm_dev_register(struct drm_device *dev, unsigned long flags)
 	const struct drm_driver *driver = dev->driver;
 	int ret;
 
-	if (!driver->load)
-		drm_mode_config_validate(dev);
+	if (!driver->load) {
+		ret = drm_mode_config_validate(dev);
+		if (ret)
+			return ret;
+	}
 
 	WARN_ON(!dev->managed.final_kfree);
 
diff --git a/drivers/gpu/drm/drm_mode_config.c b/drivers/gpu/drm/drm_mode_config.c
index 66f7dc37b597..18c6b5707532 100644
--- a/drivers/gpu/drm/drm_mode_config.c
+++ b/drivers/gpu/drm/drm_mode_config.c
@@ -674,16 +674,45 @@ static void validate_encoder_possible_crtcs(struct drm_encoder *encoder)
 	     encoder->possible_crtcs, crtc_mask);
 }
 
-void drm_mode_config_validate(struct drm_device *dev)
+static int plane_alpha_require_blend_mode(struct drm_plane *plane)
+{
+	struct drm_device *dev = plane->dev;
+	const struct drm_format_info *fmt;
+	u32 i;
+
+	/* blend mode property supported, no need to check anything */
+	if (plane->blend_mode_property)
+		return 0;
+
+	if (plane->alpha_property) {
+		drm_err(dev, "[PLANE:%d:%s] alpha property exposed but blend mode not setup",
+			plane->base.id, plane->name);
+		return -EINVAL;
+	}
+
+	for (i = 0; i < plane->format_count; i++) {
+		fmt = drm_format_info(plane->format_types[i]);
+		if (fmt->has_alpha) {
+			drm_err(dev, "[PLANE:%d:%s] pixel format with alpha exposed but blend mode not setup",
+				plane->base.id, plane->name);
+			return -EINVAL;
+		}
+	}
+
+	return 0;
+}
+
+int 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;
+	int ret = 0;
 
 	if (!drm_core_check_feature(dev, DRIVER_MODESET))
-		return;
+		return ret;
 
 	drm_for_each_encoder(encoder, dev)
 		fixup_encoder_possible_clones(encoder);
@@ -732,9 +761,13 @@ void drm_mode_config_validate(struct drm_device *dev)
 	drm_for_each_plane(plane, dev) {
 		if (plane->type == DRM_PLANE_TYPE_PRIMARY)
 			num_primary++;
+
+		ret |= plane_alpha_require_blend_mode(plane);
 	}
 
 	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);
+
+	return ret;
 }
-- 
2.54.0

Re: [PATCH v3 2/2] drm: ensure blend mode supported if alpha exposed

[Ville Syrjälä]

On Mon, May 18, 2026 at 02:54:29PM -0300, Leandro Ribeiro wrote:
> Before "drm/drm_blend: allow blend mode property without PREMULTI",
> userspace would have to assume that only PREMULTI was supported by
> drivers that didn't expose the blend mode property. But now userspace
> shouldn't relly on that, as they can't count with drivers always
> supporting PREMULTI.
> 
> Error out if a driver expose alpha property or pixel formats with alpha
> and does not expose the blend mode property. This way userspace don't
> have to guess. Drivers that hit such error must be fixed.

I don't think the error handling is a good idea. It's just another
completely untested error path that is more or less guaranteed to
break eventually. So IMO just WARN and plow ahead like we do for
everything else there.

> 
> Signed-off-by: Leandro Ribeiro <leandro.ribeiro@collabora.com>
> ---
>  drivers/gpu/drm/drm_crtc_internal.h |  2 +-
>  drivers/gpu/drm/drm_drv.c           |  7 ++++--
>  drivers/gpu/drm/drm_mode_config.c   | 37 +++++++++++++++++++++++++++--
>  3 files changed, 41 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_crtc_internal.h b/drivers/gpu/drm/drm_crtc_internal.h
> index c09409229644..2a4862202496 100644
> --- a/drivers/gpu/drm/drm_crtc_internal.h
> +++ b/drivers/gpu/drm/drm_crtc_internal.h
> @@ -95,7 +95,7 @@ int drm_mode_setcrtc(struct drm_device *dev,
>  /* drm_mode_config.c */
>  int drm_modeset_register_all(struct drm_device *dev);
>  void drm_modeset_unregister_all(struct drm_device *dev);
> -void drm_mode_config_validate(struct drm_device *dev);
> +int drm_mode_config_validate(struct drm_device *dev);
>  
>  /* drm_modes.c */
>  const char *drm_get_mode_status_name(enum drm_mode_status status);
> diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
> index 985c283cf59f..def78046a963 100644
> --- a/drivers/gpu/drm/drm_drv.c
> +++ b/drivers/gpu/drm/drm_drv.c
> @@ -1059,8 +1059,11 @@ int drm_dev_register(struct drm_device *dev, unsigned long flags)
>  	const struct drm_driver *driver = dev->driver;
>  	int ret;
>  
> -	if (!driver->load)
> -		drm_mode_config_validate(dev);
> +	if (!driver->load) {
> +		ret = drm_mode_config_validate(dev);
> +		if (ret)
> +			return ret;
> +	}
>  
>  	WARN_ON(!dev->managed.final_kfree);
>  
> diff --git a/drivers/gpu/drm/drm_mode_config.c b/drivers/gpu/drm/drm_mode_config.c
> index 66f7dc37b597..18c6b5707532 100644
> --- a/drivers/gpu/drm/drm_mode_config.c
> +++ b/drivers/gpu/drm/drm_mode_config.c
> @@ -674,16 +674,45 @@ static void validate_encoder_possible_crtcs(struct drm_encoder *encoder)
>  	     encoder->possible_crtcs, crtc_mask);
>  }
>  
> -void drm_mode_config_validate(struct drm_device *dev)
> +static int plane_alpha_require_blend_mode(struct drm_plane *plane)
> +{
> +	struct drm_device *dev = plane->dev;
> +	const struct drm_format_info *fmt;
> +	u32 i;
> +
> +	/* blend mode property supported, no need to check anything */
> +	if (plane->blend_mode_property)
> +		return 0;
> +
> +	if (plane->alpha_property) {
> +		drm_err(dev, "[PLANE:%d:%s] alpha property exposed but blend mode not setup",
> +			plane->base.id, plane->name);
> +		return -EINVAL;
> +	}
> +
> +	for (i = 0; i < plane->format_count; i++) {
> +		fmt = drm_format_info(plane->format_types[i]);
> +		if (fmt->has_alpha) {
> +			drm_err(dev, "[PLANE:%d:%s] pixel format with alpha exposed but blend mode not setup",
> +				plane->base.id, plane->name);
> +			return -EINVAL;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +int 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;
> +	int ret = 0;
>  
>  	if (!drm_core_check_feature(dev, DRIVER_MODESET))
> -		return;
> +		return ret;
>  
>  	drm_for_each_encoder(encoder, dev)
>  		fixup_encoder_possible_clones(encoder);
> @@ -732,9 +761,13 @@ void drm_mode_config_validate(struct drm_device *dev)
>  	drm_for_each_plane(plane, dev) {
>  		if (plane->type == DRM_PLANE_TYPE_PRIMARY)
>  			num_primary++;
> +
> +		ret |= plane_alpha_require_blend_mode(plane);
>  	}
>  
>  	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);
> +
> +	return ret;
>  }
> -- 
> 2.54.0

-- 
Ville Syrjälä
Intel

Re: [PATCH v3 2/2] drm: ensure blend mode supported if alpha exposed

[Ville Syrjälä]

On Mon, May 18, 2026 at 02:54:29PM -0300, Leandro Ribeiro wrote:
> Before "drm/drm_blend: allow blend mode property without PREMULTI",
> userspace would have to assume that only PREMULTI was supported by
> drivers that didn't expose the blend mode property. But now userspace
> shouldn't relly on that, as they can't count with drivers always
> supporting PREMULTI.
> 
> Error out if a driver expose alpha property or pixel formats with alpha
> and does not expose the blend mode property. This way userspace don't
> have to guess. Drivers that hit such error must be fixed.
> 
> Signed-off-by: Leandro Ribeiro <leandro.ribeiro@collabora.com>
> ---
>  drivers/gpu/drm/drm_crtc_internal.h |  2 +-
>  drivers/gpu/drm/drm_drv.c           |  7 ++++--
>  drivers/gpu/drm/drm_mode_config.c   | 37 +++++++++++++++++++++++++++--
>  3 files changed, 41 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_crtc_internal.h b/drivers/gpu/drm/drm_crtc_internal.h
> index c09409229644..2a4862202496 100644
> --- a/drivers/gpu/drm/drm_crtc_internal.h
> +++ b/drivers/gpu/drm/drm_crtc_internal.h
> @@ -95,7 +95,7 @@ int drm_mode_setcrtc(struct drm_device *dev,
>  /* drm_mode_config.c */
>  int drm_modeset_register_all(struct drm_device *dev);
>  void drm_modeset_unregister_all(struct drm_device *dev);
> -void drm_mode_config_validate(struct drm_device *dev);
> +int drm_mode_config_validate(struct drm_device *dev);
>  
>  /* drm_modes.c */
>  const char *drm_get_mode_status_name(enum drm_mode_status status);
> diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
> index 985c283cf59f..def78046a963 100644
> --- a/drivers/gpu/drm/drm_drv.c
> +++ b/drivers/gpu/drm/drm_drv.c
> @@ -1059,8 +1059,11 @@ int drm_dev_register(struct drm_device *dev, unsigned long flags)
>  	const struct drm_driver *driver = dev->driver;
>  	int ret;
>  
> -	if (!driver->load)
> -		drm_mode_config_validate(dev);
> +	if (!driver->load) {
> +		ret = drm_mode_config_validate(dev);
> +		if (ret)
> +			return ret;
> +	}
>  
>  	WARN_ON(!dev->managed.final_kfree);
>  
> diff --git a/drivers/gpu/drm/drm_mode_config.c b/drivers/gpu/drm/drm_mode_config.c
> index 66f7dc37b597..18c6b5707532 100644
> --- a/drivers/gpu/drm/drm_mode_config.c
> +++ b/drivers/gpu/drm/drm_mode_config.c
> @@ -674,16 +674,45 @@ static void validate_encoder_possible_crtcs(struct drm_encoder *encoder)
>  	     encoder->possible_crtcs, crtc_mask);
>  }
>  
> -void drm_mode_config_validate(struct drm_device *dev)
> +static int plane_alpha_require_blend_mode(struct drm_plane *plane)
> +{
> +	struct drm_device *dev = plane->dev;
> +	const struct drm_format_info *fmt;
> +	u32 i;
> +
> +	/* blend mode property supported, no need to check anything */
> +	if (plane->blend_mode_property)
> +		return 0;
> +
> +	if (plane->alpha_property) {
> +		drm_err(dev, "[PLANE:%d:%s] alpha property exposed but blend mode not setup",
> +			plane->base.id, plane->name);
> +		return -EINVAL;
> +	}

Why this? I don't think the constant alpha property has anything
really to do with the per-pixel alpha stuff.

> +
> +	for (i = 0; i < plane->format_count; i++) {
> +		fmt = drm_format_info(plane->format_types[i]);
> +		if (fmt->has_alpha) {
> +			drm_err(dev, "[PLANE:%d:%s] pixel format with alpha exposed but blend mode not setup",
> +				plane->base.id, plane->name);
> +			return -EINVAL;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +int 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;
> +	int ret = 0;
>  
>  	if (!drm_core_check_feature(dev, DRIVER_MODESET))
> -		return;
> +		return ret;
>  
>  	drm_for_each_encoder(encoder, dev)
>  		fixup_encoder_possible_clones(encoder);
> @@ -732,9 +761,13 @@ void drm_mode_config_validate(struct drm_device *dev)
>  	drm_for_each_plane(plane, dev) {
>  		if (plane->type == DRM_PLANE_TYPE_PRIMARY)
>  			num_primary++;
> +
> +		ret |= plane_alpha_require_blend_mode(plane);
>  	}
>  
>  	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);
> +
> +	return ret;
>  }
> -- 
> 2.54.0

-- 
Ville Syrjälä
Intel

Re: [PATCH v3 2/2] drm: ensure blend mode supported if alpha exposed

[Leandro Ribeiro]

On 5/22/26 3:24 PM, Ville Syrjälä wrote:
> On Mon, May 18, 2026 at 02:54:29PM -0300, Leandro Ribeiro wrote:
>> Before "drm/drm_blend: allow blend mode property without PREMULTI",
>> userspace would have to assume that only PREMULTI was supported by
>> drivers that didn't expose the blend mode property. But now userspace
>> shouldn't relly on that, as they can't count with drivers always
>> supporting PREMULTI.
>>
>> Error out if a driver expose alpha property or pixel formats with alpha
>> and does not expose the blend mode property. This way userspace don't
>> have to guess. Drivers that hit such error must be fixed.
>>
>> Signed-off-by: Leandro Ribeiro <leandro.ribeiro@collabora.com>
>> ---
>>  drivers/gpu/drm/drm_crtc_internal.h |  2 +-
>>  drivers/gpu/drm/drm_drv.c           |  7 ++++--
>>  drivers/gpu/drm/drm_mode_config.c   | 37 +++++++++++++++++++++++++++--
>>  3 files changed, 41 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_crtc_internal.h b/drivers/gpu/drm/drm_crtc_internal.h
>> index c09409229644..2a4862202496 100644
>> --- a/drivers/gpu/drm/drm_crtc_internal.h
>> +++ b/drivers/gpu/drm/drm_crtc_internal.h
>> @@ -95,7 +95,7 @@ int drm_mode_setcrtc(struct drm_device *dev,
>>  /* drm_mode_config.c */
>>  int drm_modeset_register_all(struct drm_device *dev);
>>  void drm_modeset_unregister_all(struct drm_device *dev);
>> -void drm_mode_config_validate(struct drm_device *dev);
>> +int drm_mode_config_validate(struct drm_device *dev);
>>  
>>  /* drm_modes.c */
>>  const char *drm_get_mode_status_name(enum drm_mode_status status);
>> diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
>> index 985c283cf59f..def78046a963 100644
>> --- a/drivers/gpu/drm/drm_drv.c
>> +++ b/drivers/gpu/drm/drm_drv.c
>> @@ -1059,8 +1059,11 @@ int drm_dev_register(struct drm_device *dev, unsigned long flags)
>>  	const struct drm_driver *driver = dev->driver;
>>  	int ret;
>>  
>> -	if (!driver->load)
>> -		drm_mode_config_validate(dev);
>> +	if (!driver->load) {
>> +		ret = drm_mode_config_validate(dev);
>> +		if (ret)
>> +			return ret;
>> +	}
>>  
>>  	WARN_ON(!dev->managed.final_kfree);
>>  
>> diff --git a/drivers/gpu/drm/drm_mode_config.c b/drivers/gpu/drm/drm_mode_config.c
>> index 66f7dc37b597..18c6b5707532 100644
>> --- a/drivers/gpu/drm/drm_mode_config.c
>> +++ b/drivers/gpu/drm/drm_mode_config.c
>> @@ -674,16 +674,45 @@ static void validate_encoder_possible_crtcs(struct drm_encoder *encoder)
>>  	     encoder->possible_crtcs, crtc_mask);
>>  }
>>  
>> -void drm_mode_config_validate(struct drm_device *dev)
>> +static int plane_alpha_require_blend_mode(struct drm_plane *plane)
>> +{
>> +	struct drm_device *dev = plane->dev;
>> +	const struct drm_format_info *fmt;
>> +	u32 i;
>> +
>> +	/* blend mode property supported, no need to check anything */
>> +	if (plane->blend_mode_property)
>> +		return 0;
>> +
>> +	if (plane->alpha_property) {
>> +		drm_err(dev, "[PLANE:%d:%s] alpha property exposed but blend mode not setup",
>> +			plane->base.id, plane->name);
>> +		return -EINVAL;
>> +	}
> 
> Why this? I don't think the constant alpha property has anything
> really to do with the per-pixel alpha stuff.

You’re right: if the pixel format has no alpha channel, the constant
alpha property produces identical results for COVERAGE and PREMULTI.

> 
>> +
>> +	for (i = 0; i < plane->format_count; i++) {
>> +		fmt = drm_format_info(plane->format_types[i]);
>> +		if (fmt->has_alpha) {
>> +			drm_err(dev, "[PLANE:%d:%s] pixel format with alpha exposed but blend mode not setup",
>> +				plane->base.id, plane->name);
>> +			return -EINVAL;
>> +		}
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +int 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;
>> +	int ret = 0;
>>  
>>  	if (!drm_core_check_feature(dev, DRIVER_MODESET))
>> -		return;
>> +		return ret;
>>  
>>  	drm_for_each_encoder(encoder, dev)
>>  		fixup_encoder_possible_clones(encoder);
>> @@ -732,9 +761,13 @@ void drm_mode_config_validate(struct drm_device *dev)
>>  	drm_for_each_plane(plane, dev) {
>>  		if (plane->type == DRM_PLANE_TYPE_PRIMARY)
>>  			num_primary++;
>> +
>> +		ret |= plane_alpha_require_blend_mode(plane);
>>  	}
>>  
>>  	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);
>> +
>> +	return ret;
>>  }
>> -- 
>> 2.54.0
> 

-- 
Leandro Ribeiro

Re: [PATCH v3 2/2] drm: ensure blend mode supported if alpha exposed

[Leandro Ribeiro]

On 5/22/26 3:18 PM, Ville Syrjälä wrote:
> On Mon, May 18, 2026 at 02:54:29PM -0300, Leandro Ribeiro wrote:
>> Before "drm/drm_blend: allow blend mode property without PREMULTI",
>> userspace would have to assume that only PREMULTI was supported by
>> drivers that didn't expose the blend mode property. But now userspace
>> shouldn't relly on that, as they can't count with drivers always
>> supporting PREMULTI.
>>
>> Error out if a driver expose alpha property or pixel formats with alpha
>> and does not expose the blend mode property. This way userspace don't
>> have to guess. Drivers that hit such error must be fixed.
> 
> I don't think the error handling is a good idea. It's just another
> completely untested error path that is more or less guaranteed to
> break eventually. So IMO just WARN and plow ahead like we do for
> everything else there.
> 

Sounds good to me, I'll change that in the next revision.

>>
>> Signed-off-by: Leandro Ribeiro <leandro.ribeiro@collabora.com>
>> ---
>>  drivers/gpu/drm/drm_crtc_internal.h |  2 +-
>>  drivers/gpu/drm/drm_drv.c           |  7 ++++--
>>  drivers/gpu/drm/drm_mode_config.c   | 37 +++++++++++++++++++++++++++--
>>  3 files changed, 41 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_crtc_internal.h b/drivers/gpu/drm/drm_crtc_internal.h
>> index c09409229644..2a4862202496 100644
>> --- a/drivers/gpu/drm/drm_crtc_internal.h
>> +++ b/drivers/gpu/drm/drm_crtc_internal.h
>> @@ -95,7 +95,7 @@ int drm_mode_setcrtc(struct drm_device *dev,
>>  /* drm_mode_config.c */
>>  int drm_modeset_register_all(struct drm_device *dev);
>>  void drm_modeset_unregister_all(struct drm_device *dev);
>> -void drm_mode_config_validate(struct drm_device *dev);
>> +int drm_mode_config_validate(struct drm_device *dev);
>>  
>>  /* drm_modes.c */
>>  const char *drm_get_mode_status_name(enum drm_mode_status status);
>> diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
>> index 985c283cf59f..def78046a963 100644
>> --- a/drivers/gpu/drm/drm_drv.c
>> +++ b/drivers/gpu/drm/drm_drv.c
>> @@ -1059,8 +1059,11 @@ int drm_dev_register(struct drm_device *dev, unsigned long flags)
>>  	const struct drm_driver *driver = dev->driver;
>>  	int ret;
>>  
>> -	if (!driver->load)
>> -		drm_mode_config_validate(dev);
>> +	if (!driver->load) {
>> +		ret = drm_mode_config_validate(dev);
>> +		if (ret)
>> +			return ret;
>> +	}
>>  
>>  	WARN_ON(!dev->managed.final_kfree);
>>  
>> diff --git a/drivers/gpu/drm/drm_mode_config.c b/drivers/gpu/drm/drm_mode_config.c
>> index 66f7dc37b597..18c6b5707532 100644
>> --- a/drivers/gpu/drm/drm_mode_config.c
>> +++ b/drivers/gpu/drm/drm_mode_config.c
>> @@ -674,16 +674,45 @@ static void validate_encoder_possible_crtcs(struct drm_encoder *encoder)
>>  	     encoder->possible_crtcs, crtc_mask);
>>  }
>>  
>> -void drm_mode_config_validate(struct drm_device *dev)
>> +static int plane_alpha_require_blend_mode(struct drm_plane *plane)
>> +{
>> +	struct drm_device *dev = plane->dev;
>> +	const struct drm_format_info *fmt;
>> +	u32 i;
>> +
>> +	/* blend mode property supported, no need to check anything */
>> +	if (plane->blend_mode_property)
>> +		return 0;
>> +
>> +	if (plane->alpha_property) {
>> +		drm_err(dev, "[PLANE:%d:%s] alpha property exposed but blend mode not setup",
>> +			plane->base.id, plane->name);
>> +		return -EINVAL;
>> +	}
>> +
>> +	for (i = 0; i < plane->format_count; i++) {
>> +		fmt = drm_format_info(plane->format_types[i]);
>> +		if (fmt->has_alpha) {
>> +			drm_err(dev, "[PLANE:%d:%s] pixel format with alpha exposed but blend mode not setup",
>> +				plane->base.id, plane->name);
>> +			return -EINVAL;
>> +		}
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +int 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;
>> +	int ret = 0;
>>  
>>  	if (!drm_core_check_feature(dev, DRIVER_MODESET))
>> -		return;
>> +		return ret;
>>  
>>  	drm_for_each_encoder(encoder, dev)
>>  		fixup_encoder_possible_clones(encoder);
>> @@ -732,9 +761,13 @@ void drm_mode_config_validate(struct drm_device *dev)
>>  	drm_for_each_plane(plane, dev) {
>>  		if (plane->type == DRM_PLANE_TYPE_PRIMARY)
>>  			num_primary++;
>> +
>> +		ret |= plane_alpha_require_blend_mode(plane);
>>  	}
>>  
>>  	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);
>> +
>> +	return ret;
>>  }
>> -- 
>> 2.54.0
> 

-- 
Leandro Ribeiro

Re: [PATCH v3 2/2] drm: ensure blend mode supported if alpha exposed

[kernel test robot]

Hello,

kernel test robot noticed "RIP:drm_client_sysrq_unregister[drm]" on:

commit: 45cd1cd31c81786e8c8965e6b7304bef6a3e3965 ("[PATCH v3 2/2] drm: ensure blend mode supported if alpha exposed")
url: https://github.com/intel-lab-lkp/linux/commits/Leandro-Ribeiro/drm-drm_blend-allow-blend-mode-property-without-PREMULTI/20260519-021047
patch link: https://lore.kernel.org/all/20260518175429.80615-3-leandro.ribeiro@collabora.com/
patch subject: [PATCH v3 2/2] drm: ensure blend mode supported if alpha exposed

in testcase: mdadm-selftests
version: mdadm-selftests-x86_64-3822896a-1_20251102
with following parameters:

	disk: 1HDD
	test_prefix: 19repair-does-not-destroy



config: x86_64-rhel-9.4-func
compiler: gcc-14
test machine: 8 threads 1 sockets Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz (Haswell) with 16G memory

(please refer to attached dmesg/kmsg for entire log/backtrace)



If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <oliver.sang@intel.com>
| Closes: https://lore.kernel.org/oe-lkp/202605262216.c4670030-lkp@intel.com



The kernel config and materials to reproduce are available at:
https://download.01.org/0day-ci/archive/20260526/202605262216.c4670030-lkp@intel.com


[   36.308085][  T190] i915 0000:00:02.0: [drm] *ERROR* [PLANE:47:cursor A] pixel format with alpha exposed but blend mode not setup
[   36.321077][  T190] i915 0000:00:02.0: [drm] *ERROR* [PLANE:66:cursor B] pixel format with alpha exposed but blend mode not setup
0m] Reached targ[   36.333998][   T65] ata1.00: Enabling discard_zeroes_data
[   36.370146][  T190] i915 0000:00:02.0: [drm] drm_WARN_ON(list_empty(&dev->client_sysrq_list))
[   36.370160][  T190] WARNING: drivers/gpu/drm/drm_client_sysrq.c:58 at drm_client_sysrq_unregister+0x1e2/0x2b0 [drm], CPU#2: (udev-worker)/190
[   36.392616][  T190] Modules linked in: sd_mod snd_hda_codec_alc269 sg kvm_intel snd_hda_codec_realtek_lib snd_hda_scodec_component i915(+) snd_hda_codec_generic kvm dell_wmi snd_hda_intel dell_smbios snd_hda_codec dell_wmi_descriptor intel_gtt irqbypass sparse_keymap drm_buddy snd_hda_core rapl ahci ttm snd_intel_dspcfg intel_cstate rfkill i2c_i801 snd_intel_sdw_acpi libahci drm_display_helper dcdbas mei_wdt snd_hwdep i2c_smbus intel_uncore pcspkr snd_pcm cec mei_me drm_client_lib lpc_ich snd_timer mei libata drm_kms_helper snd video wmi soundcore fuse drm nfnetlink
[   36.443051][  T190] CPU: 2 UID: 0 PID: 190 Comm: (udev-worker) Tainted: G S                  7.1.0-rc2+ #1 PREEMPT(lazy) 
[   36.454086][  T190] Tainted: [S]=CPU_OUT_OF_SPEC
[   36.458763][  T190] Hardware name: Dell Inc. OptiPlex 9020/0DNKMN, BIOS A05 12/05/2013
[   36.466765][  T190] RIP: 0010:drm_client_sysrq_unregister+0x1ec/0x2b0 [drm]
[   36.473974][  T190] Code: 85 a3 00 00 00 48 8b 6b 50 48 85 ed 74 26 48 89 df e8 e8 18 bc c2 48 89 c6 48 8d 3d 0e 56 d3 ff 48 c7 c1 e0 5d 2a c0 48 89 ea <67> 48 0f b9 3a e9 54 ff ff ff 48 b8 00 00 00 00 00 fc ff df 48 89
[   36.493547][  T190] RSP: 0018:ffffc90000abf1d0 EFLAGS: 00010246
[   36.499552][  T190] RAX: ffffffffc207c6e0 RBX: ffff88810fed00d0 RCX: ffffffffc02a5de0
[   36.507486][  T190] RDX: ffff88810db42240 RSI: ffffffffc207c6e0 RDI: ffffffffc020a400
[   36.515390][  T190] RBP: ffff88810db42240 R08: 0000000000000001 R09: fffff52000157e2f
[   36.523305][  T190] R10: ffffc90000abf17f R11: 0000000000000001 R12: 1ffff92000157e4b
[   36.531216][  T190] R13: ffff888116810038 R14: ffff888116810c58 R15: 00000000ffffffea
[   36.539120][  T190] FS:  00007ff6e25fc9c0(0000) GS:ffff8884223cc000(0000) knlGS:0000000000000000
[   36.548002][  T190] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   36.554507][  T190] CR2: 00007ff6e3131c70 CR3: 000000040da52001 CR4: 00000000001726f0
[   36.562414][  T190] Call Trace:
[   36.565612][  T190]  <TASK>
[   36.568470][  T190]  drm_dev_unregister+0x43/0x2b0 [drm]
[   36.574035][  T190]  i915_driver_probe.cold+0xd4/0x108 [i915]
[   36.581149][  T190]  ? __pfx_i915_driver_probe+0x10/0x10 [i915]
[   36.587859][  T190]  ? drm_privacy_screen_get+0x2bf/0x370 [drm]
[   36.594026][  T190]  ? intel_display_driver_probe_defer+0x41/0x70 [i915]
[   36.601922][  T190]  ? i915_pci_probe+0x2a9/0x3b0 [i915]
[   36.608026][  T190]  ? __pfx_i915_pci_probe+0x10/0x10 [i915]
[   36.614474][  T190]  local_pci_probe+0xdb/0x1b0
[   36.619092][  T190]  pci_call_probe+0x153/0x4f0
[   36.623705][  T190]  ? down_write+0xc0/0x170
[   36.628046][  T190]  ? __pfx_pci_call_probe+0x10/0x10
[   36.633180][  T190]  ? __pfx__raw_spin_lock+0x10/0x10
[   36.638320][  T190]  ? pci_assign_irq+0x80/0x2f0
[   36.643007][  T190]  ? pci_match_device+0x3ac/0x630
[   36.647958][  T190]  ? kernfs_create_link+0x164/0x230
[   36.653123][  T190]  pci_device_probe+0x175/0x2f0
[   36.657952][  T190]  call_driver_probe+0x62/0x1f0
[   36.662783][  T190]  really_probe+0x197/0x770
[   36.667229][  T190]  __driver_probe_device+0x1ca/0x3f0
[   36.672429][  T190]  driver_probe_device+0x4a/0x130
[   36.677407][  T190]  __driver_attach+0x194/0x4f0
[   36.682128][  T190]  ? __pfx___driver_attach+0x10/0x10
[   36.687355][  T190]  bus_for_each_dev+0xef/0x170
[   36.692062][  T190]  ? kasan_unpoison+0x40/0x70
[   36.696664][  T190]  ? __pfx_bus_for_each_dev+0x10/0x10
[   36.701958][  T190]  ? __kasan_slab_alloc+0x2f/0x70
[   36.706899][  T190]  ? klist_add_tail+0x132/0x270
[   36.711671][  T190]  bus_add_driver+0x2a7/0x4f0
[   36.716275][  T190]  driver_register+0x1a1/0x370
[   36.720958][  T190]  i915_init+0x57/0x160 [i915]
[   36.726406][  T190]  ? __pfx_i915_init+0x10/0x10 [i915]
[   36.732468][  T190]  do_one_initcall+0x8d/0x3f0
[   36.737064][  T190]  ? __pfx_do_one_initcall+0x10/0x10
[   36.742271][  T190]  ? memset_orig+0x84/0xb0
[   36.746610][  T190]  ? kasan_unpoison+0x40/0x70
[   36.751214][  T190]  do_init_module+0x281/0x870
[   36.755830][  T190]  ? __pfx_do_init_module+0x10/0x10
[   36.760954][  T190]  ? kfree+0x195/0x430
[   36.764954][  T190]  ? klp_module_coming+0x210/0x2f0
[   36.769992][  T190]  load_module+0x1667/0x1fb0
[   36.774509][  T190]  ? kernel_read_file+0x3d6/0x870
[   36.779461][  T190]  ? __pfx_load_module+0x10/0x10
[   36.784319][  T190]  init_module_from_file+0x157/0x1b0
[   36.789524][  T190]  ? __pfx_init_module_from_file+0x10/0x10
[   36.795243][  T190]  ? __pfx_vfs_read+0x10/0x10
[   36.799855][  T190]  ? _raw_spin_lock+0x80/0xf0
[   36.804459][  T190]  ? __pfx__raw_spin_lock+0x10/0x10
[   36.809596][  T190]  ? __x64_sys_pread64+0x18d/0x1f0
[   36.814641][  T190]  idempotent_init_module+0x21c/0x770
[   36.819932][  T190]  ? __pfx_idempotent_init_module+0x10/0x10
[   36.825745][  T190]  ? fdget+0x54/0x3b0
[   36.829663][  T190]  ? security_capable+0x35/0xf0
[   36.834444][  T190]  __x64_sys_finit_module+0xca/0x170
[   36.839650][  T190]  do_syscall_64+0xdf/0x570
[   36.844078][  T190]  ? _raw_spin_lock+0x80/0xf0
[   36.848684][  T190]  ? kasan_save_track+0x10/0x30
[   36.853460][  T190]  ? __x64_sys_openat+0x104/0x1f0
[   36.858405][  T190]  ? put_unused_fd+0x104/0x1f0
[   36.863095][  T190]  ? __pfx___x64_sys_openat+0x10/0x10
[   36.868395][  T190]  ? do_sys_openat2+0xeb/0x170
[   36.873076][  T190]  ? seccomp_run_filters+0xb5/0x4f0
[   36.878194][  T190]  ? do_syscall_64+0x116/0x570
[   36.882882][  T190]  ? __seccomp_filter+0x22d/0xbf0
[   36.887848][  T190]  ? __x64_sys_openat+0x104/0x1f0
[   36.892842][  T190]  ? __pfx___seccomp_filter+0x10/0x10
[   36.898133][  T190]  ? security_capable+0x35/0xf0
[   36.902904][  T190]  ? do_syscall_64+0x116/0x570
[   36.907580][  T190]  ? do_syscall_64+0x94/0x570
[   36.912175][  T190]  ? irqentry_exit+0x3d/0x530
[   36.916772][  T190]  entry_SYSCALL_64_after_hwframe+0x76/0x7e
[   36.922603][  T190] RIP: 0033:0x7ff6e3158779
[   36.926944][  T190] Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 4f 86 0d 00 f7 d8 64 89 01 48
[   36.946501][  T190] RSP: 002b:00007fff7aae0e28 EFLAGS: 00000246 ORIG_RAX: 0000000000000139
[   36.954835][  T190] RAX: ffffffffffffffda RBX: 000055cc60482540 RCX: 00007ff6e3158779
[   36.962812][  T190] RDX: 0000000000000000 RSI: 00007ff6e195e44d RDI: 000000000000001c
[   36.970709][  T190] RBP: 0000000000000000 R08: 0000000000000000 R09: 000055cc6043e1e0
[   36.978618][  T190] R10: 0000000000000000 R11: 0000000000000246 R12: 00007ff6e195e44d
[   36.986506][  T190] R13: 0000000000020000 R14: 000055cc6047ee40 R15: 0000000000000000
[   36.994404][  T190]  </TASK>
[   36.997339][  T190] ---[ end trace 0000000000000000 ]---
[   37.005688][   T65]  sda: sda1 sda2
[   37.009989][   T65] sd 0:0:0:0: [sda] Attached SCSI disk
[   37.071483][   T69]  sdb: sdb1 sdb2 sdb3 sdb4
[   37.077745][   T69] sd 2:0:0:0: [sdb] Attached SCSI disk
[   37.117310][   T21] intel_rapl_common: Found RAPL domain package
[   37.124147][   T21] intel_rapl_common: Found RAPL domain core
[   37.129992][   T21] intel_rapl_common: Found RAPL domain uncore
[   37.136203][   T21] intel_rapl_common: Found RAPL domain dram
[   37.142081][   T21] intel_rapl_common: package-0:package:long_term locked by BIOS
[   37.149636][   T21] intel_rapl_common: package-0:package:short_term locked by BIOS
[   37.159446][  T520] xor: automatically using best checksumming function   avx       
[   37.172690][  T520] raid6: skipped pq benchmark and selected avx2x4
[   37.179019][  T520] raid6: using avx2x2 recovery algorithm
[   37.233537][  T190] ------------[ cut here ]------------
[   37.238941][  T190] WARNING: drivers/gpu/drm/drm_mode_config.c:551 at drm_mode_config_cleanup+0x709/0x970 [drm], CPU#0: (udev-worker)/190
[   37.251547][  T190] Modules linked in: libblake2b zstd_compress raid6_pq xor intel_rapl_msr intel_rapl_common x86_pkg_temp_thermal intel_powerclamp coretemp sd_mod snd_hda_codec_alc269 sg kvm_intel snd_hda_codec_realtek_lib snd_hda_scodec_component i915(+) snd_hda_codec_generic kvm dell_wmi snd_hda_intel dell_smbios snd_hda_codec dell_wmi_descriptor intel_gtt irqbypass sparse_keymap drm_buddy snd_hda_core rapl ahci ttm snd_intel_dspcfg intel_cstate rfkill i2c_i801 snd_intel_sdw_acpi libahci drm_display_helper dcdbas mei_wdt snd_hwdep i2c_smbus intel_uncore pcspkr snd_pcm cec mei_me drm_client_lib lpc_ich snd_timer mei libata drm_kms_helper snd video wmi soundcore fuse drm nfnetlink
[   37.312666][  T190] CPU: 0 UID: 0 PID: 190 Comm: (udev-worker) Tainted: G S      W           7.1.0-rc2+ #1 PREEMPT(lazy) 
[   37.323948][  T190] Tainted: [S]=CPU_OUT_OF_SPEC, [W]=WARN
[   37.329713][  T190] Hardware name: Dell Inc. OptiPlex 9020/0DNKMN, BIOS A05 12/05/2013
[   37.337905][  T190] RIP: 0010:drm_mode_config_cleanup+0x709/0x970 [drm]
[   37.344776][  T190] Code: 84 24 c8 00 00 00 65 48 2b 05 cb 74 4d c7 0f 85 3a 02 00 00 48 81 c4 d0 00 00 00 5b 5d 41 5c 41 5d 41 5e 41 5f c3 cc cc cc cc <0f> 0b 49 bd 00 00 00 00 00 fc ff df 48 89 de 48 89 ef e8 a0 8e fa
[   37.364363][  T190] RSP: 0018:ffffc90000abf110 EFLAGS: 00010287
[   37.370385][  T190] RAX: ffff88815b67a020 RBX: ffffc90000abf140 RCX: 1ffff92000157e0d
[   37.378322][  T190] RDX: 1ffff11022d02047 RSI: fffff52000157de8 RDI: ffffc90000abf070
[   37.386226][  T190] RBP: ffff888116810000 R08: 0000000000000001 R09: fffff52000157dd4
[   37.394141][  T190] R10: 0000000000000003 R11: 0000000000000007 R12: ffff888116810278
[   37.402055][  T190] R13: ffff888116810238 R14: ffff888116810278 R15: dffffc0000000000
[   37.409967][  T190] FS:  00007ff6e25fc9c0(0000) GS:ffff8884222cc000(0000) knlGS:0000000000000000
[   37.418849][  T190] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   37.425372][  T190] CR2: 00007ff6e30b0000 CR3: 000000040da52003 CR4: 00000000001726f0
[   37.433291][  T190] Call Trace:
[   37.436512][  T190]  <TASK>
[   37.439393][  T190]  ? __pfx_drm_mode_config_cleanup+0x10/0x10 [drm]
[   37.446075][  T190]  ? kfree+0x195/0x430
[   37.450092][  T190]  ? intel_atomic_global_obj_cleanup+0x29e/0x530 [i915]
[   37.458027][  T190]  intel_display_driver_remove_noirq+0xc2/0x230 [i915]
[   37.465889][  T190]  i915_driver_probe+0x935/0x9f0 [i915]
[   37.472388][  T190]  ? __pfx_i915_driver_probe+0x10/0x10 [i915]
[   37.479405][  T190]  ? drm_privacy_screen_get+0x2bf/0x370 [drm]
[   37.485609][  T190]  ? intel_display_driver_probe_defer+0x41/0x70 [i915]
[   37.493583][  T190]  ? i915_pci_probe+0x2a9/0x3b0 [i915]
[   37.500188][  T190]  ? __pfx_i915_pci_probe+0x10/0x10 [i915]
[   37.507004][  T190]  local_pci_probe+0xdb/0x1b0
[   37.511650][  T190]  pci_call_probe+0x153/0x4f0
[   37.516275][  T190]  ? down_write+0xc0/0x170
[   37.520636][  T190]  ? __pfx_pci_call_probe+0x10/0x10
[   37.525783][  T190]  ? __pfx__raw_spin_lock+0x10/0x10
[   37.530930][  T190]  ? pci_assign_irq+0x80/0x2f0
[   37.535637][  T190]  ? pci_match_device+0x3ac/0x630
[   37.540612][  T190]  ? kernfs_create_link+0x164/0x230
[   37.545776][  T190]  pci_device_probe+0x175/0x2f0
[   37.550578][  T190]  call_driver_probe+0x62/0x1f0
[   37.555390][  T190]  really_probe+0x197/0x770
[   37.559846][  T190]  __driver_probe_device+0x1ca/0x3f0
[   37.565083][  T190]  driver_probe_device+0x4a/0x130
[   37.570058][  T190]  __driver_attach+0x194/0x4f0
[   37.574779][  T190]  ? __pfx___driver_attach+0x10/0x10
[   37.580011][  T190]  bus_for_each_dev+0xef/0x170
[   37.584726][  T190]  ? kasan_unpoison+0x40/0x70
[   37.589352][  T190]  ? __pfx_bus_for_each_dev+0x10/0x10
[   37.594675][  T190]  ? __kasan_slab_alloc+0x2f/0x70
[   37.599647][  T190]  ? klist_add_tail+0x132/0x270
[   37.604487][  T190]  bus_add_driver+0x2a7/0x4f0
[   37.609107][  T190]  driver_register+0x1a1/0x370
[   37.613853][  T190]  i915_init+0x57/0x160 [i915]
[   37.619564][  T190]  ? __pfx_i915_init+0x10/0x10 [i915]
[   37.625860][  T190]  do_one_initcall+0x8d/0x3f0
[   37.630498][  T190]  ? __pfx_do_one_initcall+0x10/0x10
[   37.635732][  T190]  ? memset_orig+0x84/0xb0
[   37.640108][  T190]  ? kasan_unpoison+0x40/0x70
[   37.644749][  T190]  do_init_module+0x281/0x870
[   37.649381][  T190]  ? __pfx_do_init_module+0x10/0x10
[   37.654530][  T190]  ? kfree+0x195/0x430
[   37.658546][  T190]  ? klp_module_coming+0x210/0x2f0
[   37.663620][  T190]  load_module+0x1667/0x1fb0
[   37.668176][  T190]  ? kernel_read_file+0x3d6/0x870
[   37.673155][  T190]  ? __pfx_load_module+0x10/0x10
[   37.678076][  T190]  init_module_from_file+0x157/0x1b0
[   37.683314][  T190]  ? __pfx_init_module_from_file+0x10/0x10
[   37.689091][  T190]  ? __pfx_vfs_read+0x10/0x10
[   37.693734][  T190]  ? _raw_spin_lock+0x80/0xf0
[   37.698364][  T190]  ? __pfx__raw_spin_lock+0x10/0x10
[   37.703536][  T190]  ? __x64_sys_pread64+0x18d/0x1f0
[   37.708609][  T190]  idempotent_init_module+0x21c/0x770
[   37.713938][  T190]  ? __pfx_idempotent_init_module+0x10/0x10
[   37.719795][  T190]  ? fdget+0x54/0x3b0
[   37.723712][  T190]  ? security_capable+0x35/0xf0
[   37.728512][  T190]  __x64_sys_finit_module+0xca/0x170
[   37.733736][  T190]  do_syscall_64+0xdf/0x570
[   37.738181][  T190]  ? _raw_spin_lock+0x80/0xf0
[   37.742810][  T190]  ? kasan_save_track+0x10/0x30
[   37.747601][  T190]  ? __x64_sys_openat+0x104/0x1f0
[   37.752567][  T190]  ? put_unused_fd+0x104/0x1f0
[   37.757275][  T190]  ? __pfx___x64_sys_openat+0x10/0x10
[   37.762592][  T190]  ? do_sys_openat2+0xeb/0x170
[   37.767312][  T190]  ? seccomp_run_filters+0xb5/0x4f0
[   37.772455][  T190]  ? do_syscall_64+0x116/0x570
[   37.777165][  T190]  ? __seccomp_filter+0x22d/0xbf0
[   37.782131][  T190]  ? __x64_sys_openat+0x104/0x1f0
[   37.787102][  T190]  ? __pfx___seccomp_filter+0x10/0x10
[   37.792422][  T190]  ? security_capable+0x35/0xf0
[   37.797224][  T190]  ? do_syscall_64+0x116/0x570
[   37.801922][  T190]  ? do_syscall_64+0x94/0x570
[   37.806529][  T190]  ? irqentry_exit+0x3d/0x530
[   37.811144][  T190]  entry_SYSCALL_64_after_hwframe+0x76/0x7e
[   37.816984][  T190] RIP: 0033:0x7ff6e3158779
[   37.821337][  T190] Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 4f 86 0d 00 f7 d8 64 89 01 48
[   37.840933][  T190] RSP: 002b:00007fff7aae0e28 EFLAGS: 00000246 ORIG_RAX: 0000000000000139
[   37.849295][  T190] RAX: ffffffffffffffda RBX: 000055cc60482540 RCX: 00007ff6e3158779
[   37.857259][  T190] RDX: 0000000000000000 RSI: 00007ff6e195e44d RDI: 000000000000001c
[   37.865197][  T190] RBP: 0000000000000000 R08: 0000000000000000 R09: 000055cc6043e1e0
[   37.873157][  T190] R10: 0000000000000000 R11: 0000000000000246 R12: 00007ff6e195e44d
[   37.881096][  T190] R13: 0000000000020000 R14: 000055cc6047ee40 R15: 0000000000000000
[   37.889023][  T190]  </TASK>
[   37.891991][  T190] ---[ end trace 0000000000000000 ]---
[   37.897469][  T190] [drm:drm_mode_config_cleanup [drm]] *ERROR* connector VGA-1 leaked!
[   37.932701][  T520] Btrfs loaded, zoned=yes, fsverity=yes
[   38.011268][  T190] i915 0000:00:02.0: [drm] *ERROR* Device initialization failed (-22)
[   38.019369][  T190] i915 0000:00:02.0: probe with driver i915 failed with error -22
[   38.027343][   T91] ------------[ cut here ]------------
[   38.032748][   T91] ida_free called for id=0 which is not allocated.
[   38.039189][   T91] WARNING: lib/idr.c:594 at ida_free+0x161/0x230, CPU#1: kworker/1:1/91
[   38.047468][   T91] Modules linked in: btrfs libblake2b zstd_compress raid6_pq xor intel_rapl_msr intel_rapl_common x86_pkg_temp_thermal intel_powerclamp coretemp sd_mod snd_hda_codec_alc269 sg kvm_intel snd_hda_codec_realtek_lib snd_hda_scodec_component i915(+) snd_hda_codec_generic kvm dell_wmi snd_hda_intel dell_smbios snd_hda_codec dell_wmi_descriptor intel_gtt irqbypass sparse_keymap drm_buddy snd_hda_core rapl ahci ttm snd_intel_dspcfg intel_cstate rfkill i2c_i801 snd_intel_sdw_acpi libahci drm_display_helper dcdbas mei_wdt snd_hwdep i2c_smbus intel_uncore pcspkr snd_pcm cec mei_me drm_client_lib lpc_ich snd_timer mei libata drm_kms_helper snd video wmi soundcore fuse drm nfnetlink
[   38.108723][   T91] CPU: 1 UID: 0 PID: 91 Comm: kworker/1:1 Tainted: G S      W           7.1.0-rc2+ #1 PREEMPT(lazy) 
[   38.119510][   T91] Tainted: [S]=CPU_OUT_OF_SPEC, [W]=WARN
[   38.125066][   T91] Hardware name: Dell Inc. OptiPlex 9020/0DNKMN, BIOS A05 12/05/2013
[   38.133066][   T91] Workqueue: events drm_connector_free_work_fn [drm]
[   38.139866][   T91] RIP: 0010:ida_free+0x163/0x230
[   38.144741][   T91] Code: 24 28 31 f6 e8 fe 15 08 00 e9 a1 00 00 00 41 83 fe 3e 76 5e 48 8b 7c 24 28 4c 89 ee e8 e6 98 0b 00 48 8d 3d 4f 29 53 02 89 ee <67> 48 0f b9 3a 48 b8 00 00 00 00 00 fc ff df 48 01 c3 c7 03 00 00
[   38.164311][   T91] RSP: 0018:ffffc9000067fb98 EFLAGS: 00010286
[   38.170307][   T91] RAX: 0000000000000000 RBX: 1ffff920000cff74 RCX: 1ffff920000cff7b
[   38.178238][   T91] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff868934c0
[   38.186154][   T91] RBP: 0000000000000000 R08: 0000000000000001 R09: fffff520000cff67
[   38.194064][   T91] R10: 0000000000000003 R11: 0000000000000005 R12: 0000000000000000
[   38.201972][   T91] R13: 0000000000000246 R14: 0000000000000000 R15: ffffc9000067fbc0
[   38.209890][   T91] FS:  0000000000000000(0000) GS:ffff88842234c000(0000) knlGS:0000000000000000
[   38.218765][   T91] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   38.225293][   T91] CR2: 00007fb72fb563d8 CR3: 000000040da52001 CR4: 00000000001726f0
[   38.233206][   T91] Call Trace:
[   38.236416][   T91]  <TASK>
[   38.239283][   T91]  ? __pfx_ida_free+0x10/0x10
[   38.243915][   T91]  ? radix_tree_delete_item+0x90/0x1b0
[   38.249312][   T91]  ? __pfx_radix_tree_delete_item+0x10/0x10
[   38.255168][   T91]  drm_connector_cleanup+0x514/0xdb0 [drm]
[   38.261104][   T91]  intel_connector_destroy+0x4b/0xb0 [i915]
[   38.267981][   T91]  drm_connector_free_work_fn+0xcd/0x130 [drm]
[   38.274222][   T91]  process_one_work+0x6b4/0x1030
[   38.279109][   T91]  ? __pfx_drm_connector_free_work_fn+0x10/0x10 [drm]
[   38.285980][   T91]  ? assign_work+0x131/0x3f0
[   38.290496][   T91]  worker_thread+0x51d/0xdb0
[   38.295024][   T91]  ? __kthread_parkme+0xb1/0x1f0
[   38.299898][   T91]  ? __pfx_worker_thread+0x10/0x10
[   38.304942][   T91]  ? __pfx_worker_thread+0x10/0x10
[   38.309999][   T91]  kthread+0x353/0x470
[   38.314007][   T91]  ? recalc_sigpending+0x159/0x1f0
[   38.319056][   T91]  ? __pfx_kthread+0x10/0x10
[   38.323578][   T91]  ret_from_fork+0x32f/0x670
[   38.328099][   T91]  ? __pfx_ret_from_fork+0x10/0x10
[   38.333155][   T91]  ? switch_fpu+0x15/0x1f0
[   38.337516][   T91]  ? __switch_to+0x508/0xe70
[   38.342041][   T91]  ? __switch_to_asm+0x33/0x70
[   38.346751][   T91]  ? __pfx_kthread+0x10/0x10
[   38.351274][   T91]  ret_from_fork_asm+0x1a/0x30
[   38.355988][   T91]  </TASK>
[   38.358932][   T91] ---[ end trace 0000000000000000 ]---
[   38.364377][   T91] ------------[ cut here ]------------
[   38.369776][   T91] refcount_t: underflow; use-after-free.
[   38.375568][   T91] WARNING: lib/refcount.c:28 at refcount_warn_saturate+0xa9/0xf0, CPU#1: kworker/1:1/91
[   38.385356][   T91] Modules linked in: btrfs libblake2b zstd_compress raid6_pq xor intel_rapl_msr intel_rapl_common x86_pkg_temp_thermal intel_powerclamp coretemp sd_mod snd_hda_codec_alc269 sg kvm_intel snd_hda_codec_realtek_lib snd_hda_scodec_component i915(+) snd_hda_codec_generic kvm dell_wmi snd_hda_intel dell_smbios snd_hda_codec dell_wmi_descriptor intel_gtt irqbypass sparse_keymap drm_buddy snd_hda_core rapl ahci ttm snd_intel_dspcfg intel_cstate rfkill i2c_i801 snd_intel_sdw_acpi libahci drm_display_helper dcdbas mei_wdt snd_hwdep i2c_smbus intel_uncore pcspkr snd_pcm cec mei_me drm_client_lib lpc_ich snd_timer mei libata drm_kms_helper snd video wmi soundcore fuse drm nfnetlink
[   38.446718][   T91] CPU: 1 UID: 0 PID: 91 Comm: kworker/1:1 Tainted: G S      W           7.1.0-rc2+ #1 PREEMPT(lazy) 
[   38.457641][   T91] Tainted: [S]=CPU_OUT_OF_SPEC, [W]=WARN
[   38.463327][   T91] Hardware name: Dell Inc. OptiPlex 9020/0DNKMN, BIOS A05 12/05/2013
[   38.471341][   T91] Workqueue: events drm_connector_free_work_fn [drm]
[   38.478149][   T91] RIP: 0010:refcount_warn_saturate+0xa9/0xf0
[   38.484071][   T91] Code: cd a4 e7 03 67 48 0f b9 3a 5b 5d c3 cc cc cc cc 48 8d 3d ca a4 e7 03 67 48 0f b9 3a 5b 5d c3 cc cc cc cc 48 8d 3d c7 a4 e7 03 <67> 48 0f b9 3a 5b 5d c3 cc cc cc cc 48 8d 3d c4 a4 e7 03 67 48 0f
[   38.503658][   T91] RSP: 0018:ffffc9000067fc30 EFLAGS: 00010246
[   38.509667][   T91] RAX: 0000000000000003 RBX: ffff88815b67a050 RCX: ffffffff82a08aa1
[   38.517584][   T91] RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffffffff86883000
[   38.525488][   T91] RBP: 0000000000000003 R08: 0000000000000001 R09: ffffed102b6cf40a
[   38.533393][   T91] R10: ffff88815b67a053 R11: 0000000000000005 R12: ffff888116810000
[   38.541298][   T91] R13: ffff88815b67a028 R14: ffff888116810220 R15: ffff88810d8b2800
[   38.549204][   T91] FS:  0000000000000000(0000) GS:ffff88842234c000(0000) knlGS:0000000000000000
[   38.558075][   T91] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   38.564597][   T91] CR2: 00007fb72fb563d8 CR3: 000000040da52001 CR4: 00000000001726f0
[   38.572532][   T91] Call Trace:
[   38.575746][   T91]  <TASK>
[   38.578607][   T91]  __drm_atomic_helper_connector_destroy_state+0x59/0x170 [drm_kms_helper]
[   38.587210][   T91]  drm_atomic_helper_connector_destroy_state+0x11/0x30 [drm_kms_helper]
[   38.595555][   T91]  drm_connector_cleanup+0x86d/0xdb0 [drm]
[   38.601480][   T91]  intel_connector_destroy+0x4b/0xb0 [i915]
[   38.608401][   T91]  drm_connector_free_work_fn+0xcd/0x130 [drm]
[   38.614668][   T91]  process_one_work+0x6b4/0x1030
[   38.619544][   T91]  ? __pfx_drm_connector_free_work_fn+0x10/0x10 [drm]
[   38.626419][   T91]  ? assign_work+0x131/0x3f0
[   38.630952][   T91]  worker_thread+0x51d/0xdb0
[   38.635491][   T91]  ? __kthread_parkme+0xb1/0x1f0
[   38.640369][   T91]  ? __pfx_worker_thread+0x10/0x10
[   38.645413][   T91]  ? __pfx_worker_thread+0x10/0x10
[   38.650453][   T91]  kthread+0x353/0x470
[   38.654447][   T91]  ? recalc_sigpending+0x159/0x1f0
[   38.659490][   T91]  ? __pfx_kthread+0x10/0x10
[   38.664011][   T91]  ret_from_fork+0x32f/0x670
[   38.668541][   T91]  ? __pfx_ret_from_fork+0x10/0x10
[   38.673590][   T91]  ? switch_fpu+0x15/0x1f0
[   38.677940][   T91]  ? __switch_to+0x508/0xe70
[   38.682462][   T91]  ? __switch_to_asm+0x33/0x70
[   38.687168][   T91]  ? __pfx_kthread+0x10/0x10
[   38.691689][   T91]  ret_from_fork_asm+0x1a/0x30
[   38.696395][   T91]  </TASK>
[   38.699344][   T91] ---[ end trace 0000000000000000 ]---


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https://github.com/intel/lkp-tests/wiki