[PATCH RESEND v2 12/32] drm/vkms: Introduce configfs for plane color encoding

Louis Chauvet posted 32 patches 3 months, 1 week ago
There is a newer version of this series
[PATCH RESEND v2 12/32] drm/vkms: Introduce configfs for plane color encoding
Posted by Louis Chauvet 3 months, 1 week ago
To allows the userspace to test many hardware configuration, introduce a
new interface to configure the available color encoding per planes. VKMS
supports multiple color encoding, so the userspace can choose any
combination.

The supported color encoding are configured by writing a color encoding
bitmask to the file `supported_color_encoding` and the default color
encoding is chosen by writing a color encoding bitmask to
`default_color_encoding`.

Signed-off-by: Louis Chauvet <louis.chauvet@bootlin.com>
---
 Documentation/gpu/vkms.rst           |  7 ++-
 drivers/gpu/drm/vkms/vkms_configfs.c | 98 ++++++++++++++++++++++++++++++++++++
 2 files changed, 104 insertions(+), 1 deletion(-)

diff --git a/Documentation/gpu/vkms.rst b/Documentation/gpu/vkms.rst
index eac1a942d6c4..dab6811687a2 100644
--- a/Documentation/gpu/vkms.rst
+++ b/Documentation/gpu/vkms.rst
@@ -87,7 +87,7 @@ Start by creating one or more planes::
 
   sudo mkdir /config/vkms/my-vkms/planes/plane0
 
-Planes have 4 configurable attributes:
+Planes have 6 configurable attributes:
 
 - type: Plane type: 0 overlay, 1 primary, 2 cursor (same values as those
   exposed by the "type" property of a plane)
@@ -97,6 +97,11 @@ Planes have 4 configurable attributes:
   (same values as those exposed by the "rotation" property of a plane)
 - default_rotation: Default rotation presented to the userspace, same values as
   possible_rotations.
+- supported_color_encoding: Available encoding for a plane, as a bitmask:
+  0x01 YCBCR_BT601, 0x02: YCBCR_BT709, 0x04 YCBCR_BT2020 (same values as those exposed
+  by the COLOR_ENCODING property of a plane)
+- default_color_encoding: Default color encoding presented to the userspace, same
+  values as supported_color_encoding
 
 Continue by creating one or more CRTCs::
 
diff --git a/drivers/gpu/drm/vkms/vkms_configfs.c b/drivers/gpu/drm/vkms/vkms_configfs.c
index 7cc8ba315ef0..ee2e8d141f9e 100644
--- a/drivers/gpu/drm/vkms/vkms_configfs.c
+++ b/drivers/gpu/drm/vkms/vkms_configfs.c
@@ -439,16 +439,114 @@ static ssize_t plane_default_rotation_store(struct config_item *item,
 	return count;
 }
 
+static ssize_t plane_supported_color_encodings_show(struct config_item *item, char *page)
+{
+	struct vkms_configfs_plane *plane;
+	unsigned int supported_color_encoding;
+
+	plane = plane_item_to_vkms_configfs_plane(item);
+
+	scoped_guard(mutex, &plane->dev->lock) {
+		supported_color_encoding = vkms_config_plane_get_supported_color_encodings(plane->config);
+	}
+
+	return sprintf(page, "%u", supported_color_encoding);
+}
+
+static ssize_t plane_supported_color_encodings_store(struct config_item *item,
+						     const char *page, size_t count)
+{
+	struct vkms_configfs_plane *plane = plane_item_to_vkms_configfs_plane(item);
+	int ret, val = 0;
+
+	ret = kstrtouint(page, 10, &val);
+	if (ret)
+		return ret;
+
+	/* Should be a supported value */
+	if (val & ~(BIT(DRM_COLOR_YCBCR_BT601) |
+		    BIT(DRM_COLOR_YCBCR_BT709) |
+		    BIT(DRM_COLOR_YCBCR_BT2020)))
+		return -EINVAL;
+	/* Should at least provide one color range */
+	if ((val & (BIT(DRM_COLOR_YCBCR_BT601) |
+		    BIT(DRM_COLOR_YCBCR_BT709) |
+		    BIT(DRM_COLOR_YCBCR_BT2020))) == 0)
+		return -EINVAL;
+
+	scoped_guard(mutex, &plane->dev->lock) {
+		/* Ensures that the default rotation is included in supported rotation */
+		if (plane->dev->enabled)
+			return -EINVAL;
+
+		vkms_config_plane_set_supported_color_encodings(plane->config, val);
+	}
+
+	return count;
+}
+
+/* Plane default_color_encoding : vkms/<device>/planes/<plane>/default_color_encoding */
+
+static ssize_t plane_default_color_encoding_show(struct config_item *item, char *page)
+{
+	struct vkms_configfs_plane *plane;
+	unsigned int default_color_encoding;
+
+	plane = plane_item_to_vkms_configfs_plane(item);
+
+	scoped_guard(mutex, &plane->dev->lock) {
+		default_color_encoding = vkms_config_plane_get_default_color_encoding(plane->config);
+	}
+
+	return sprintf(page, "%u", default_color_encoding);
+}
+
+static ssize_t plane_default_color_encoding_store(struct config_item *item,
+						  const char *page, size_t count)
+{
+	struct vkms_configfs_plane *plane = plane_item_to_vkms_configfs_plane(item);
+	int ret, val = 0;
+
+	ret = kstrtouint(page, 10, &val);
+	if (ret)
+		return ret;
+
+	/* Should be a supported value */
+	if (val & ~(BIT(DRM_COLOR_YCBCR_BT601) |
+		    BIT(DRM_COLOR_YCBCR_BT709) |
+		    BIT(DRM_COLOR_YCBCR_BT2020)))
+		return -EINVAL;
+	/* Should at least provide one color range */
+	if ((val & (BIT(DRM_COLOR_YCBCR_BT601) |
+		    BIT(DRM_COLOR_YCBCR_BT709) |
+		    BIT(DRM_COLOR_YCBCR_BT2020))) == 0)
+		return -EINVAL;
+
+	scoped_guard(mutex, &plane->dev->lock) {
+		/* Ensures that the default rotation is included in supported rotation */
+		if (plane->dev->enabled)
+			return -EINVAL;
+
+		vkms_config_plane_set_default_color_encoding(plane->config, val);
+	}
+
+	return count;
+}
+
 CONFIGFS_ATTR(plane_, type);
 CONFIGFS_ATTR(plane_, name);
 CONFIGFS_ATTR(plane_, supported_rotations);
 CONFIGFS_ATTR(plane_, default_rotation);
+CONFIGFS_ATTR(plane_, supported_color_encodings);
+CONFIGFS_ATTR(plane_, default_color_encoding);
 
 static struct configfs_attribute *plane_item_attrs[] = {
 	&plane_attr_type,
 	&plane_attr_name,
 	&plane_attr_supported_rotations,
 	&plane_attr_default_rotation,
+	&plane_attr_supported_color_encodings,
+	&plane_attr_default_color_encoding,
 	NULL,
 };
 

-- 
2.51.0
Re: [PATCH RESEND v2 12/32] drm/vkms: Introduce configfs for plane color encoding
Posted by Luca Ceresoli 1 month, 3 weeks ago
On Wed Oct 29, 2025 at 3:36 PM CET, Louis Chauvet wrote:
> To allows the userspace to test many hardware configuration, introduce a
> new interface to configure the available color encoding per planes. VKMS
> supports multiple color encoding, so the userspace can choose any
> combination.
>
> The supported color encoding are configured by writing a color encoding
> bitmask to the file `supported_color_encoding` and the default color
> encoding is chosen by writing a color encoding bitmask to
> `default_color_encoding`.
>
> Signed-off-by: Louis Chauvet <louis.chauvet@bootlin.com>
> ---
>  Documentation/gpu/vkms.rst           |  7 ++-
>  drivers/gpu/drm/vkms/vkms_configfs.c | 98 ++++++++++++++++++++++++++++++++++++
>  2 files changed, 104 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/gpu/vkms.rst b/Documentation/gpu/vkms.rst
> index eac1a942d6c4..dab6811687a2 100644
> --- a/Documentation/gpu/vkms.rst
> +++ b/Documentation/gpu/vkms.rst
> @@ -87,7 +87,7 @@ Start by creating one or more planes::
>
>    sudo mkdir /config/vkms/my-vkms/planes/plane0
>
> -Planes have 4 configurable attributes:
> +Planes have 6 configurable attributes:
>
>  - type: Plane type: 0 overlay, 1 primary, 2 cursor (same values as those
>    exposed by the "type" property of a plane)
> @@ -97,6 +97,11 @@ Planes have 4 configurable attributes:
>    (same values as those exposed by the "rotation" property of a plane)
>  - default_rotation: Default rotation presented to the userspace, same values as
>    possible_rotations.
> +- supported_color_encoding: Available encoding for a plane, as a bitmask:
                                         encodings

> +  0x01 YCBCR_BT601, 0x02: YCBCR_BT709, 0x04 YCBCR_BT2020 (same values as those exposed
                           ^

Unintended colon? While I think it's nice to have, there is none elsewhere,
even in previous patches, and I'd say we can live happy without.

> +  by the COLOR_ENCODING property of a plane)
> +- default_color_encoding: Default color encoding presented to the userspace, same
> +  values as supported_color_encoding
>
>  Continue by creating one or more CRTCs::
>
> diff --git a/drivers/gpu/drm/vkms/vkms_configfs.c b/drivers/gpu/drm/vkms/vkms_configfs.c
> index 7cc8ba315ef0..ee2e8d141f9e 100644
> --- a/drivers/gpu/drm/vkms/vkms_configfs.c
> +++ b/drivers/gpu/drm/vkms/vkms_configfs.c
> @@ -439,16 +439,114 @@ static ssize_t plane_default_rotation_store(struct config_item *item,
>  	return count;
>  }
>
> +static ssize_t plane_supported_color_encodings_show(struct config_item *item, char *page)
> +{
> +	struct vkms_configfs_plane *plane;
> +	unsigned int supported_color_encoding;
                     supported_color_encodings

> +
> +	plane = plane_item_to_vkms_configfs_plane(item);

As for patch 9, for consistency:

  struct vkms_configfs_plane *plane = plane_item_to_vkms_configfs_plane(item);

> +
> +	scoped_guard(mutex, &plane->dev->lock) {
> +		supported_color_encoding = vkms_config_plane_get_supported_color_encodings(plane->config);
> +	}
> +
> +	return sprintf(page, "%u", supported_color_encoding);
> +}
> +
> +static ssize_t plane_supported_color_encodings_store(struct config_item *item,
> +						     const char *page, size_t count)
> +{
> +	struct vkms_configfs_plane *plane = plane_item_to_vkms_configfs_plane(item);
> +	int ret, val = 0;
> +
> +	ret = kstrtouint(page, 10, &val);
> +	if (ret)
> +		return ret;
> +
> +	/* Should be a supported value */
> +	if (val & ~(BIT(DRM_COLOR_YCBCR_BT601) |
> +		    BIT(DRM_COLOR_YCBCR_BT709) |
> +		    BIT(DRM_COLOR_YCBCR_BT2020)))
> +		return -EINVAL;
> +	/* Should at least provide one color range */
> +	if ((val & (BIT(DRM_COLOR_YCBCR_BT601) |
> +		    BIT(DRM_COLOR_YCBCR_BT709) |
> +		    BIT(DRM_COLOR_YCBCR_BT2020))) == 0)

I'm mentioning here as it comes to mind, but it's valid for other similar
patches in this series: why not adding a

  #define DRM_COLOR_ENCODINGS_SUPPORTED ( \
                   BIT(DRM_COLOR_YCBCR_BT601) |
                   BIT(DRM_COLOR_YCBCR_BT709) |
                   BIT(DRM_COLOR_YCBCR_BT2020))

and use it in place of the various bitwise-or sequences?

This would simplify work later on if adding a new color encoding (or color
range, or...).

Somewhat like DRM_MODE_*_MASK.

> +		return -EINVAL;
> +
> +	scoped_guard(mutex, &plane->dev->lock) {
> +		/* Ensures that the default rotation is included in supported rotation */
> +		if (plane->dev->enabled)
> +			return -EINVAL;

And here the comment is definitely wrong. :-)

> +
> +		vkms_config_plane_set_supported_color_encodings(plane->config, val);
> +	}
> +
> +	return count;
> +}
> +
> +/* Plane default_color_encoding : vkms/<device>/planes/<plane>/default_color_encoding */

There's no such comment in other places, so for consistency remove it (or
add it everywhere?!? ... no, just kidding).

> +
> +static ssize_t plane_default_color_encoding_show(struct config_item *item, char *page)
> +{
> +	struct vkms_configfs_plane *plane;
> +	unsigned int default_color_encoding;
> +
> +	plane = plane_item_to_vkms_configfs_plane(item);
> +
> +	scoped_guard(mutex, &plane->dev->lock) {
> +		default_color_encoding = vkms_config_plane_get_default_color_encoding(plane->config);
> +	}
> +
> +	return sprintf(page, "%u", default_color_encoding);
> +}
> +
> +static ssize_t plane_default_color_encoding_store(struct config_item *item,
> +						  const char *page, size_t count)
> +{
> +	struct vkms_configfs_plane *plane = plane_item_to_vkms_configfs_plane(item);
> +	int ret, val = 0;
> +
> +	ret = kstrtouint(page, 10, &val);
> +	if (ret)
> +		return ret;
> +
> +	/* Should be a supported value */
> +	if (val & ~(BIT(DRM_COLOR_YCBCR_BT601) |
> +		    BIT(DRM_COLOR_YCBCR_BT709) |
> +		    BIT(DRM_COLOR_YCBCR_BT2020)))
> +		return -EINVAL;
> +	/* Should at least provide one color range */
> +	if ((val & (BIT(DRM_COLOR_YCBCR_BT601) |
> +		    BIT(DRM_COLOR_YCBCR_BT709) |
> +		    BIT(DRM_COLOR_YCBCR_BT2020))) == 0)
> +		return -EINVAL;

Shouldn't you check that exactly one bit is set? As in patch 9.

> +
> +	scoped_guard(mutex, &plane->dev->lock) {
> +		/* Ensures that the default rotation is included in supported rotation */
> +		if (plane->dev->enabled)
> +			return -EINVAL;

As before, wrong comment.

Luca

--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
Re: [PATCH RESEND v2 12/32] drm/vkms: Introduce configfs for plane color encoding
Posted by Louis Chauvet 1 month, 3 weeks ago

On 12/18/25 18:59, Luca Ceresoli wrote:
> On Wed Oct 29, 2025 at 3:36 PM CET, Louis Chauvet wrote:
>> To allows the userspace to test many hardware configuration, introduce a
>> new interface to configure the available color encoding per planes. VKMS
>> supports multiple color encoding, so the userspace can choose any
>> combination.
>>
>> The supported color encoding are configured by writing a color encoding
>> bitmask to the file `supported_color_encoding` and the default color
>> encoding is chosen by writing a color encoding bitmask to
>> `default_color_encoding`.
>>
>> Signed-off-by: Louis Chauvet <louis.chauvet@bootlin.com>
>> ---
>>   Documentation/gpu/vkms.rst           |  7 ++-
>>   drivers/gpu/drm/vkms/vkms_configfs.c | 98 ++++++++++++++++++++++++++++++++++++
>>   2 files changed, 104 insertions(+), 1 deletion(-)
>>
>> diff --git a/Documentation/gpu/vkms.rst b/Documentation/gpu/vkms.rst
>> index eac1a942d6c4..dab6811687a2 100644
>> --- a/Documentation/gpu/vkms.rst
>> +++ b/Documentation/gpu/vkms.rst
>> @@ -87,7 +87,7 @@ Start by creating one or more planes::
>>
>>     sudo mkdir /config/vkms/my-vkms/planes/plane0
>>
>> -Planes have 4 configurable attributes:
>> +Planes have 6 configurable attributes:
>>
>>   - type: Plane type: 0 overlay, 1 primary, 2 cursor (same values as those
>>     exposed by the "type" property of a plane)
>> @@ -97,6 +97,11 @@ Planes have 4 configurable attributes:
>>     (same values as those exposed by the "rotation" property of a plane)
>>   - default_rotation: Default rotation presented to the userspace, same values as
>>     possible_rotations.
>> +- supported_color_encoding: Available encoding for a plane, as a bitmask:
>                                           encodings
> 
>> +  0x01 YCBCR_BT601, 0x02: YCBCR_BT709, 0x04 YCBCR_BT2020 (same values as those exposed
>                             ^
> 
> Unintended colon? While I think it's nice to have, there is none elsewhere,
> even in previous patches, and I'd say we can live happy without.
> 
>> +  by the COLOR_ENCODING property of a plane)
>> +- default_color_encoding: Default color encoding presented to the userspace, same
>> +  values as supported_color_encoding
>>
>>   Continue by creating one or more CRTCs::
>>
>> diff --git a/drivers/gpu/drm/vkms/vkms_configfs.c b/drivers/gpu/drm/vkms/vkms_configfs.c
>> index 7cc8ba315ef0..ee2e8d141f9e 100644
>> --- a/drivers/gpu/drm/vkms/vkms_configfs.c
>> +++ b/drivers/gpu/drm/vkms/vkms_configfs.c
>> @@ -439,16 +439,114 @@ static ssize_t plane_default_rotation_store(struct config_item *item,
>>   	return count;
>>   }
>>
>> +static ssize_t plane_supported_color_encodings_show(struct config_item *item, char *page)
>> +{
>> +	struct vkms_configfs_plane *plane;
>> +	unsigned int supported_color_encoding;
>                       supported_color_encodings
> 
>> +
>> +	plane = plane_item_to_vkms_configfs_plane(item);
> 
> As for patch 9, for consistency:
> 
>    struct vkms_configfs_plane *plane = plane_item_to_vkms_configfs_plane(item);
> 
>> +
>> +	scoped_guard(mutex, &plane->dev->lock) {
>> +		supported_color_encoding = vkms_config_plane_get_supported_color_encodings(plane->config);
>> +	}
>> +
>> +	return sprintf(page, "%u", supported_color_encoding);
>> +}
>> +
>> +static ssize_t plane_supported_color_encodings_store(struct config_item *item,
>> +						     const char *page, size_t count)
>> +{
>> +	struct vkms_configfs_plane *plane = plane_item_to_vkms_configfs_plane(item);
>> +	int ret, val = 0;
>> +
>> +	ret = kstrtouint(page, 10, &val);
>> +	if (ret)
>> +		return ret;
>> +
>> +	/* Should be a supported value */
>> +	if (val & ~(BIT(DRM_COLOR_YCBCR_BT601) |
>> +		    BIT(DRM_COLOR_YCBCR_BT709) |
>> +		    BIT(DRM_COLOR_YCBCR_BT2020)))
>> +		return -EINVAL;
>> +	/* Should at least provide one color range */
>> +	if ((val & (BIT(DRM_COLOR_YCBCR_BT601) |
>> +		    BIT(DRM_COLOR_YCBCR_BT709) |
>> +		    BIT(DRM_COLOR_YCBCR_BT2020))) == 0)
> 
> I'm mentioning here as it comes to mind, but it's valid for other similar
> patches in this series: why not adding a
> 
>    #define DRM_COLOR_ENCODINGS_SUPPORTED ( \
>                     BIT(DRM_COLOR_YCBCR_BT601) |
>                     BIT(DRM_COLOR_YCBCR_BT709) |
>                     BIT(DRM_COLOR_YCBCR_BT2020))
> 
> and use it in place of the various bitwise-or sequences?
> 
> This would simplify work later on if adding a new color encoding (or color
> range, or...).
> 
> Somewhat like DRM_MODE_*_MASK.
> 
>> +		return -EINVAL;
>> +
>> +	scoped_guard(mutex, &plane->dev->lock) {
>> +		/* Ensures that the default rotation is included in supported rotation */
>> +		if (plane->dev->enabled)
>> +			return -EINVAL;
> 
> And here the comment is definitely wrong. :-)
> 
>> +
>> +		vkms_config_plane_set_supported_color_encodings(plane->config, val);
>> +	}
>> +
>> +	return count;
>> +}
>> +
>> +/* Plane default_color_encoding : vkms/<device>/planes/<plane>/default_color_encoding */
> 
> There's no such comment in other places, so for consistency remove it (or
> add it everywhere?!? ... no, just kidding).
> 
>> +
>> +static ssize_t plane_default_color_encoding_show(struct config_item *item, char *page)
>> +{
>> +	struct vkms_configfs_plane *plane;
>> +	unsigned int default_color_encoding;
>> +
>> +	plane = plane_item_to_vkms_configfs_plane(item);
>> +
>> +	scoped_guard(mutex, &plane->dev->lock) {
>> +		default_color_encoding = vkms_config_plane_get_default_color_encoding(plane->config);
>> +	}
>> +
>> +	return sprintf(page, "%u", default_color_encoding);
>> +}
>> +
>> +static ssize_t plane_default_color_encoding_store(struct config_item *item,
>> +						  const char *page, size_t count)
>> +{
>> +	struct vkms_configfs_plane *plane = plane_item_to_vkms_configfs_plane(item);
>> +	int ret, val = 0;
>> +
>> +	ret = kstrtouint(page, 10, &val);
>> +	if (ret)
>> +		return ret;
>> +
>> +	/* Should be a supported value */
>> +	if (val & ~(BIT(DRM_COLOR_YCBCR_BT601) |
>> +		    BIT(DRM_COLOR_YCBCR_BT709) |
>> +		    BIT(DRM_COLOR_YCBCR_BT2020)))
>> +		return -EINVAL;
>> +	/* Should at least provide one color range */
>> +	if ((val & (BIT(DRM_COLOR_YCBCR_BT601) |
>> +		    BIT(DRM_COLOR_YCBCR_BT709) |
>> +		    BIT(DRM_COLOR_YCBCR_BT2020))) == 0)
>> +		return -EINVAL;
> 
> Shouldn't you check that exactly one bit is set? As in patch 9.

Because this code is wrong... the default rotation should be 
DRM_COLOR_YCBCR_BT601 / DRM_COLOR_YCBCR_BT709 / DRM_COLOR_YCBCR_BT2020
not a bitfield...

>> +
>> +	scoped_guard(mutex, &plane->dev->lock) {
>> +		/* Ensures that the default rotation is included in supported rotation */
>> +		if (plane->dev->enabled)
>> +			return -EINVAL;
> 
> As before, wrong comment.
> 
> Luca
> 
> --
> Luca Ceresoli, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com
Re: [PATCH RESEND v2 12/32] drm/vkms: Introduce configfs for plane color encoding
Posted by Louis Chauvet 1 month, 3 weeks ago
>>> +
>>> +    ret = kstrtouint(page, 10, &val);
>>> +    if (ret)
>>> +        return ret;
>>> +
>>> +    /* Should be a supported value */
>>> +    if (val & ~(BIT(DRM_COLOR_YCBCR_BT601) |
>>> +            BIT(DRM_COLOR_YCBCR_BT709) |
>>> +            BIT(DRM_COLOR_YCBCR_BT2020)))
>>> +        return -EINVAL;
>>> +    /* Should at least provide one color range */
>>> +    if ((val & (BIT(DRM_COLOR_YCBCR_BT601) |
>>> +            BIT(DRM_COLOR_YCBCR_BT709) |
>>> +            BIT(DRM_COLOR_YCBCR_BT2020))) == 0)
>>> +        return -EINVAL;
>>
>> Shouldn't you check that exactly one bit is set? As in patch 9.
> 
> Because this code is wrong... the default rotation should be 
> DRM_COLOR_YCBCR_BT601 / DRM_COLOR_YCBCR_BT709 / DRM_COLOR_YCBCR_BT2020
> not a bitfield...

And after fixing this, I think I will keep bitmask with only one bit set 
so supported_color_encodings and default_color_encoding will have 
exactly the same values. Same for color ranges. Thanks for the report!

> 
>>> +
>>> +    scoped_guard(mutex, &plane->dev->lock) {
>>> +        /* Ensures that the default rotation is included in 
>>> supported rotation */
>>> +        if (plane->dev->enabled)
>>> +            return -EINVAL;
>>
>> As before, wrong comment.
>>
>> Luca
>>
>> -- 
>> Luca Ceresoli, Bootlin
>> Embedded Linux and Kernel engineering
>> https://bootlin.com
>