[PATCH v8 1/3] drm/plane: Add new plane property IN_FORMATS_ASYNC

[Borah, Chaitanya Kumar]

> -----Original Message-----
> From: Murthy, Arun R <arun.r.murthy at intel.com>
> Sent: Wednesday, March 12, 2025 6:39 PM
> To: dri-devel at lists.freedesktop.org; intel-gfx at lists.freedesktop.org; intel-
> xe at lists.freedesktop.org
> Cc: Borah, Chaitanya Kumar <chaitanya.kumar.borah at intel.com>;
> 20250219093211.4059187-1-arun.r.murthy at intel.com;
> 20250311085422.2573860-1-santhosh.reddy.guddati at intel.com; Murthy,
> Arun R <arun.r.murthy at intel.com>; Kumar, Naveen1
> <naveen1.kumar at intel.com>
> Subject: [PATCH v8 1/3] drm/plane: Add new plane property
> IN_FORMATS_ASYNC
> 
> There exists a property IN_FORMATS which exposes the plane supported
> modifiers/formats to the user. In some platforms when asynchronous flip are
> used all of modifiers/formats mentioned in IN_FORMATS are not supported.
> This patch adds a new plane property IN_FORMATS_ASYNC to expose the
> async flip supported modifiers/formats so that user can use this information
> ahead and do flip with unsupported formats/modifiers. This will save flip
> failures.
> Add a new function pointer similar to format_mod_supported specifically for
> asynchronous flip.
> 
> v2: Remove async variable from drm_plane (Ville)
> v3: Add new function pointer for async (Ville)
> v5: Typo corrected in commit message & some correction in the kernel
> documentation. (Chaitanya)
> v7: Place IN_FORMATS_ASYNC next to IN_FORMATS (Ville)
> v8: replace uint32_t with u32 and uint64_t with u64 (Chaitanya)
> 
> Signed-off-by: Arun R Murthy <arun.r.murthy at intel.com>
> Tested-by: Naveen Kumar <naveen1.kumar at intel.com>
> ---
>  drivers/gpu/drm/drm_mode_config.c |  7 +++++++
>  drivers/gpu/drm/drm_plane.c       | 12 ++++++++++--
>  include/drm/drm_mode_config.h     |  6 ++++++
>  include/drm/drm_plane.h           | 17 +++++++++++++++++
>  4 files changed, 40 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_mode_config.c
> b/drivers/gpu/drm/drm_mode_config.c
> index
> 8642a2fb25a90116dab975aa0ab6b51deafb4b96..b4239fd04e9da4d4b5cfc
> cdef1d3dde9556f322d 100644
> --- a/drivers/gpu/drm/drm_mode_config.c
> +++ b/drivers/gpu/drm/drm_mode_config.c
> @@ -381,6 +381,13 @@ static int
> drm_mode_create_standard_properties(struct drm_device *dev)
>  		return -ENOMEM;
>  	dev->mode_config.modifiers_property = prop;
> 
> +	prop = drm_property_create(dev,
> +				   DRM_MODE_PROP_IMMUTABLE |
> DRM_MODE_PROP_BLOB,
> +				   "IN_FORMATS_ASYNC", 0);
> +	if (!prop)
> +		return -ENOMEM;
> +	dev->mode_config.async_modifiers_property = prop;
> +
>  	prop = drm_property_create(dev,
>  				   DRM_MODE_PROP_IMMUTABLE |
> DRM_MODE_PROP_BLOB,
>  				   "SIZE_HINTS", 0);
> diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c
> index
> a28b22fdd7a41aca82d097d42237851da9a0a79b..110838c3e5920835e08
> 75e57e6e479bcab7c8733 100644
> --- a/drivers/gpu/drm/drm_plane.c
> +++ b/drivers/gpu/drm/drm_plane.c
> @@ -141,6 +141,14 @@
>   *     various bugs in this area with inconsistencies between the capability
>   *     flag and per-plane properties.
>   *
> + * IN_FORMATS_ASYNC:
> + *     Blob property which contains the set of buffer format and modifier
> + *     pairs supported by this plane for asynchronous flips. The blob is a struct
> + *     drm_format_modifier_blob. Userspace cannot change this property. This
> is an
> + *     optional property and if not present then user should expect a failure in
> + *     atomic ioctl when the modifier/format is not supported by that plane
> under
> + *     asynchronous flip.
> + *
>   * SIZE_HINTS:
>   *     Blob property which contains the set of recommended plane size
>   *     which can used for simple "cursor like" use cases (eg. no scaling).
> @@ -197,7 +205,7 @@ static int create_in_format_blob(struct drm_device
> *dev, struct drm_plane *plane
>  	formats_size = sizeof(__u32) * plane->format_count;
>  	if (WARN_ON(!formats_size)) {
>  		/* 0 formats are never expected */
> -		return 0;
> +		return ERR_PTR(0);

...

>  	}
> 
>  	modifiers_size =
> @@ -213,7 +221,7 @@ static int create_in_format_blob(struct drm_device
> *dev, struct drm_plane *plane
> 
>  	blob = drm_property_create_blob(dev, blob_size, NULL);
>  	if (IS_ERR(blob))
> -		return -1;
> +		return ERR_PTR(-1);

Were we seeing any warnings because of this?
If at all needed, it should be part of the second patch [1]

Regards

Chaitanya

[1] https://patchwork.freedesktop.org/patch/642713/?series=140935&rev=8


> 
>  	blob_data = blob->data;
>  	blob_data->version = FORMAT_BLOB_CURRENT; diff --git
> a/include/drm/drm_mode_config.h b/include/drm/drm_mode_config.h
> index
> 271765e2e9f2da62aaf0d258828ef4196e14822e..0c116d6dfd277262b1a4c
> 0f097fce2d719f43844 100644
> --- a/include/drm/drm_mode_config.h
> +++ b/include/drm/drm_mode_config.h
> @@ -936,6 +936,12 @@ struct drm_mode_config {
>  	 */
>  	struct drm_property *modifiers_property;
> 
> +	/**
> +	 * @async_modifiers_property: Plane property to list support
> modifier/format
> +	 * combination for asynchronous flips.
> +	 */
> +	struct drm_property *async_modifiers_property;
> +
>  	/**
>  	 * @size_hints_property: Plane SIZE_HINTS property.
>  	 */
> diff --git a/include/drm/drm_plane.h b/include/drm/drm_plane.h index
> dd718c62ac31bf16606f3ee9f025a5b171cd1e67..01479dd94e76a8389a0c
> 9e9d6744400aa2291064 100644
> --- a/include/drm/drm_plane.h
> +++ b/include/drm/drm_plane.h
> @@ -549,6 +549,23 @@ struct drm_plane_funcs {
>  	 */
>  	bool (*format_mod_supported)(struct drm_plane *plane, uint32_t
> format,
>  				     uint64_t modifier);
> +	/**
> +	 * @format_mod_supported_async:
> +	 *
> +	 * This optional hook is used for the DRM to determine if for
> +	 * asynchronous flip the given format/modifier combination is valid for
> +	 * the plane. This allows the DRM to generate the correct format
> +	 * bitmask (which formats apply to which modifier), and to validate
> +	 * modifiers at atomic_check time.
> +	 *
> +	 * Returns:
> +	 *
> +	 * True if the given modifier is valid for that format on the plane.
> +	 * False otherwise.
> +	 */
> +	bool (*format_mod_supported_async)(struct drm_plane *plane,
> +					   u32 format, u64 modifier);
> +
>  };
> 
>  /**
> 
> --
> 2.25.1