Re: [PATCH v7 39/44] [media] uapi/media.h: Add MEDIA_IOC_G_TOPOLOGY ioctl

[Hans Verkuil <hverkuil@xs4all.nl>]

On 08/23/15 22:17, Mauro Carvalho Chehab wrote:
> Add a new ioctl that will report the entire topology on
> one go.
> 
> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
> 
> diff --git a/include/media/media-entity.h b/include/media/media-entity.h
> index 796e4a490af8..0111d9652b78 100644
> --- a/include/media/media-entity.h
> +++ b/include/media/media-entity.h
> @@ -181,6 +181,8 @@ struct media_interface {
>   */
>  struct media_intf_devnode {
>  	struct media_interface		intf;
> +
> +	/* Should match the fields at media_v2_intf_devnode */
>  	u32				major;
>  	u32				minor;
>  };
> diff --git a/include/uapi/linux/media.h b/include/uapi/linux/media.h
> index ceea791dd6e9..7fcf7f477ae3 100644
> --- a/include/uapi/linux/media.h
> +++ b/include/uapi/linux/media.h
> @@ -238,11 +238,94 @@ struct media_links_enum {
>  #define MEDIA_INTF_T_ALSA_RAWMIDI       (MEDIA_INTF_T_ALSA_BASE + 4)
>  #define MEDIA_INTF_T_ALSA_HWDEP         (MEDIA_INTF_T_ALSA_BASE + 5)
>  
> -/* TBD: declare the structs needed for the new G_TOPOLOGY ioctl */
> +/*
> + * MC next gen API definitions
> + *
> + * NOTE: The declarations below are close to the MC RFC for the Media
> + *	 Controller, the next generation. Yet, there are a few adjustments
> + *	 to do, as we want to be able to have a functional API before
> + *	 the MC properties change. Those will be properly marked below.
> + *	 Please also notice that I removed "num_pads", "num_links",
> + *	 from the proposal, as a proper userspace application will likely
> + *	 use lists for pads/links, just as we intend todo in Kernelspace.
> + *	 The API definition should be freed from fields that are bound to
> + *	 some specific data structure.
> + *
> + * FIXME: Currently, I opted to name the new types as "media_v2", as this
> + *	  won't cause any conflict with the Kernelspace namespace, nor with
> + *	  the previous kAPI media_*_desc namespace. This can be changed
> + *	  latter, before the adding this API upstream.
> + */
> +
> +
> +#define MEDIA_NEW_LNK_FL_ENABLED		MEDIA_LNK_FL_ENABLED
> +#define MEDIA_NEW_LNK_FL_IMMUTABLE		MEDIA_LNK_FL_IMMUTABLE
> +#define MEDIA_NEW_LNK_FL_DYNAMIC		MEDIA_NEW_FL_DYNAMIC
> +#define MEDIA_NEW_LNK_FL_INTERFACE_LINK		(1 << 3)
> +
> +struct media_v2_entity {
> +	__u32 id;
> +	char name[64];		/* FIXME: move to a property? (RFC says so) */
> +	__u16 reserved[14];
> +};
> +
> +/* Should match the specific fields at media_intf_devnode */
> +struct media_v2_intf_devnode {
> +	__u32 major;
> +	__u32 minor;
> +};
> +
> +struct media_v2_interface {
> +	__u32 id;
> +	__u32 intf_type;
> +	__u32 flags;
> +	__u32 reserved[9];
> +
> +	union {
> +		struct media_v2_intf_devnode devnode;
> +		__u32 raw[16];
> +	};
> +};
> +
> +struct media_v2_pad {
> +	__u32 id;
> +	__u32 entity_id;
> +	__u32 flags;
> +	__u16 reserved[9];
> +};
> +
> +struct media_v2_link {
> +    __u32 id;
> +    __u32 source_id;
> +    __u32 sink_id;
> +    __u32 flags;
> +    __u32 reserved[5];
> +};
> +
> +struct media_v2_topology {
> +	__u32 topology_version;
> +
> +	__u32 num_entities;
> +	struct media_v2_entity *entities;
> +
> +	__u32 num_interfaces;
> +	struct media_v2_interface *interfaces;
> +
> +	__u32 num_pads;
> +	struct media_v2_pad *pads;
> +
> +	__u32 num_links;
> +	struct media_v2_link *links;
> +
> +	__u32 reserved[64];

As I suggested elsewhere, replace this by:

	struct {
		__u32 num_reserved;
		void *ptr_reserved;
	} reserved_ptrs[8];

This will keep the number of reserved num/pointer pairs identical
between 32 and 64 bit architectures. Without that doing compat32
handling will be very difficult indeed.

We might want a separate __u32 reserved[] array so we're able to add
non-pointer fields in the future.

Regards,

	Hans

> +};
> +
> +/* ioctls */
>  
>  #define MEDIA_IOC_DEVICE_INFO		_IOWR('|', 0x00, struct media_device_info)
>  #define MEDIA_IOC_ENUM_ENTITIES		_IOWR('|', 0x01, struct media_entity_desc)
>  #define MEDIA_IOC_ENUM_LINKS		_IOWR('|', 0x02, struct media_links_enum)
>  #define MEDIA_IOC_SETUP_LINK		_IOWR('|', 0x03, struct media_link_desc)
> +#define MEDIA_IOC_G_TOPOLOGY		_IOWR('|', 0x04, struct media_v2_topology)
>  
>  #endif /* __LINUX_MEDIA_H */
>