Instead of flagging an interface link as MEDIA_LNK_FL_INTERFACE_LINK
only when returning to userspace, do it at link creation time.

That would allow using such flag internally, and cleans up a
little bit the code for G_TOPOLOGY ioctl.

[mchehab@osg.samsung.com: folded with a fixup from Dan Carpenter,
 replacing & by &&]
Suggested-by: NHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

Commit 86ee417578a2 ("[media] media: convert links from array to list")
had many changes that were automated using coccinelle but the semantic
patch was not smart enough to rely on operators precedence and avoid
using unnecessary enclosing parenthesis.

This patch removes them since are not needed.
Suggested-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NJavier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

Several additional functions are described at media-entity.c.
Moving them to the header file, to make the code cleaner and
to have all such macros at the same place.
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

Those media_obj_* functions are actually creating/destroying
media graph objects. So, rename them to better represent
what they're actually doing.

No functional changes.

This was created via this small shell script:

	for i in $(git grep -l media_gobj_init); do sed s,media_gobj_init,media_gobj_create,g <$i >a && mv a $i; done
	for i in $(git grep -l media_gobj_remove); do sed s,media_gobj_remove,media_gobj_destroy,g <$i >a && mv a $i; done
Suggested-by: NSakari Ailus <sakari.ailus@iki.fi>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

> > > +		if (rlink != link->reverse) {
> > > +			r++;
> >
> > The variable is incremented here but otherwise never used, you can remove it.
Suggested-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

Move this function to happen earlier, in order to avoid
a uneeded forward declaration.
Suggested-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

No functional changes.
Suggested-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

This function was used in the past to free the links
that were allocated by the media controller core.

However, this is not needed anymore. We should likely
get rid of the funcion on some function, but, for now,
let's just convert into an inlined function and let the
compiler to get rid of it.
Suggested-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

With the MC next gen rework, what's left for media_entity_init()
is to just initialize the PADs. However, certain devices, like
a FLASH led/light doesn't have any input or output PAD.

So, there's no reason why calling media_entity_init() would be
mandatory. Also, despite its name, what this function actually
does is to initialize the PADs data. So, rename it to
media_entity_pads_init() in order to reflect that.

The media entity actual init happens during entity register,
at media_device_register_entity(). We should move init of
num_links and num_backlinks to it.
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

If an entity is registered with a media device before is initialized
with media_device_register_entity(), the number of pads won't be set
so media_device_register_entity() won't create pad objects and add
it to the media device pads list.

Do this at entity initialization time if the entity was registered
before so the graph is complete and correct regardless of the order
in which the entities are initialized and registered.
Suggested-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>
Signed-off-by: NJavier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

We should not be creating device nodes at IRQ contexts. So,
the only flags we'll be using will be GFP_KERNEL. Let's
remove the gfp_flags, in order to make the interface simpler.

If we ever need it, it would be easy to revert those changes.

While here, remove an extra blank line.
Suggested-by: NSakari Ailus <sakari.ailus@iki.fi>
Acked-by: NHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

Due to the graph traversal algorithm currently in usage, we
need a copy of all data links. Those backlinks should not be
send to userspace, as otherwise, all links there will be
duplicated.
Acked-by: NHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

The logic is testing if num_links==0 at the wrong place. Due to
that, a backlink may be kept without removal, causing KASAN
to complain about usage after free during either entity or
link removal.
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

The media_entity_cleanup() function only cleans up the entity links list
but this operation is already made in media_device_unregister_entity().

In most cases this should be harmless (besides having duplicated code)
since the links list would be empty so the iteration would not happen
but the links list is initialized in media_device_register_entity() so
if a driver fails to register an entity with a media device and clean up
the entity in the error path, a NULL deference pointer error will happen.

So don't try to empty the links list in media_entity_cleanup() since
is either done already or haven't been initialized yet.
Signed-off-by: NJavier Martinez Canillas <javier@osg.samsung.com>

Some parts of the media controller are using mutexes while
others are using spin locks in order to protect creation
and removal of elements in the graph. That's wrong!

Also, the V4L2 core can remove graph elements on non-interactive
context:
	BUG: sleeping function called from invalid context at include/linux/sched.h:2776

Fix it by always using spin locks for graph element addition/removal,
just like entity creation/removal is protected at media-device.c
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

Just like what's done with entities, when the media controller is
unregistered, release any interface and interface links that
might still be there.
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

Add functions to explicitly unregister all entity links.
This function is called automatically when an entity
link is destroyed.
Acked-by: NHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

Every time a graph object is added or removed, the version
of the topology changes. That's a requirement for the new
MEDIA_IOC_G_TOPOLOGY, in order to allow userspace to know
that the topology has changed after a previous call to it.
Acked-by: NHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

The MC next gen API sends objects to userspace grouped by
their types.

In the case of pads and links, in order to improve performance
and have a simpler code, the best is to store them also on
separate linked lists at MC.

If we don't do that, we would need this kind of interaction
to send data to userspace (code is in structured english):

	for each entity:
		for each pad:
			store pads

	for each entity:
		for each link:
			store link

	for each interface:
		for each link:
			store link

With would require one nested loop for pads and two nested
loops for links. By using  separate linked lists for them,
just one loop would be enough.
Acked-by: NHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

Let's control the topology changes inside the graph_object. So, move the
addition and removal of interfaces/entities from the mdev lists to
media_gobj_init() and media_gobj_remove().

The main reason is that mdev should have lists for all object types, as
the new MC api will require to store objects in separate places.
Acked-by: NHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

Sometimes, it is important to see if the created pad is
sink or source. Add info to track that.
Acked-by: NHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

The media device should list the interface objects, so add a linked list
for those interfaces in struct media_device.
Acked-by: NHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

As we'll be adding other interface types in the future, put the
common interface create code on a separate function.
Suggested-by: NHans Verkuil <hans.verkuil@cisco.com>
Acked-by: NHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

Now that we have a new graph object called "interfaces", we
need to be able to link them to the entities.

Add a linked list to the interfaces to allow them to be
linked to the entities.
Acked-by: NHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

Remove entity name from the link as this exists only if the object
type is PAD on both link ends.
Acked-by: NHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

The media_entity_add_link() function takes an entity
as an argument just to get the list head.

Make it more generic by changing the function argument
to list_head.

No functional changes.
Acked-by: NHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

The entire logic that represent graph links were developed on a
time where there were no needs to dynamic remove links. So,
although links are created/removed one by one via some
functions, they're stored as an array inside the entity struct.

As the array may grow, there's a logic inside the code that
checks if the amount of space is not enough to store
the needed links. If it isn't the core uses krealloc()
to change the size of the link, with is bad, as it
leaves the memory fragmented.

So, convert links into a list.

Also, currently,  both source and sink entities need the link
at the graph traversal logic inside media_entity. So there's
a logic duplicating all links. That makes it to spend
twice the memory needed. This is not a big deal for today's
usage, where the number of links are not big.

Yet, if during the MC workshop discussions, it was said that
IIO graphs could have up to 4,000 entities. So, we may
want to remove the duplication on some future. The problem
is that it would require a separate linked list to store
the backlinks inside the entity, or to use a more complex
algorithm to do graph backlink traversal, with is something
that the current graph traversal inside the core can't cope
with. So, let's postpone a such change if/when it is actually
needed.

It should also be noticed that the media_link structure uses
44 bytes on 32-bit architectures and 84 bytes on 64-bit
architecture. It will thus be allocated out of the 64-bytes and
96-bytes pools respectively. That's a 12.5% memory waste on
64-bit architectures and 31.25% on 32-bit architecture.
A linked list is less efficient than an array in this case, but
this could later be optimized if we can get rid of the reverse
links (with would reduce memory allocation by 50%).
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

Links are graph objects that represent the links of two already
existing objects in the graph.

While with the current implementation, it is possible to create
the links earlier, It doesn't make any sense to allow linking
two objects when they are not both created.

So, remove the code that would be handling those early-created
links and add a BUG_ON() to ensure that.
Acked-by: NHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

Interfaces are different than entities: they represent a
Kernel<->userspace interaction, while entities represent a
piece of hardware/firmware/software that executes a function.

Let's distinguish them by creating a separate structure to
store the interfaces.

Later patches should change the existing drivers and logic
to split the current interface embedded inside the entity
structure (device nodes) into a separate object of the graph.
Acked-by: NHans Verkuil <hans.verkuil@cisco.com>
Reviewed-by: NJavier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

The struct media_entity has a .parent field that stores a pointer
to the parent struct media_device. But recently a media_gobj was
embedded into the entities and since struct media_gojb already has
a pointer to a struct media_device in the .mdev field, the .parent
field becomes redundant and can be removed.

This patch replaces all the usage of .parent by .graph_obj.mdev so
that field will become unused and can be removed on a later patch.

No functional changes.

The transformation was made using the following coccinelle spatch:

@@
struct media_entity *me;
@@

- me->parent
+ me->graph_obj.mdev

@@
struct media_entity *link;
@@

- link->source->entity->parent
+ link->source->entity->graph_obj.mdev

@@
struct exynos_video_entity *ve;
@@

- ve->vdev.entity.parent
+ ve->vdev.entity.graph_obj.mdev
Suggested-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>
Signed-off-by: NJavier Martinez Canillas <javier@osg.samsung.com>
Acked-by: NHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

With the new API, a link can be either between two PADs or between an interface
and an entity. So, we need to use a better name for the function that create
links between two pads.

So, rename the such function to media_create_pad_link().

No functional changes.

This patch was created via this shell script:
	for i in $(find drivers/media -name '*.[ch]' -type f) $(find drivers/staging/media -name '*.[ch]' -type f) $(find include/ -name '*.h' -type f) ; do sed s,media_entity_create_link,media_create_pad_link,g <$i >a && mv a $i; done
Acked-by: NHans Verkuil <hans.verkuil@cisco.com>
Tested-by: NJavier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

It helps to check if the media controller is doing the
right thing with the object creation and removal.

No extra code/data will be produced if DEBUG or
CONFIG_DYNAMIC_DEBUG is not enabled.
Acked-by: NHans Verkuil <hans.verkuil@cisco.com>
Reviewed-by: NJavier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

Just like entities and pads, links also need to have unique
Object IDs along a given media controller.

So, let's add a media_gobj inside it and initialize
the object then a new link is created.
Acked-by: NHans Verkuil <hans.verkuil@cisco.com>
Tested-by: NJavier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

PADs also need unique object IDs that won't conflict with
the entity object IDs.

The pad objects are currently created via media_entity_init()
and, once created, never change.

While this will likely change in the future in order to
support dynamic changes, for now we'll keep PADs as arrays
and initialize the media_gobj embedded structs when
registering the entity.
Acked-by: NHans Verkuil <hans.verkuil@cisco.com>
Tested-by: NJavier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

As entities are graph objects, let's embed media_gobj
on it. That ensures an unique ID for entities that can be
global along the entire media controller.

For now, we'll keep the already existing entity ID. Such
field need to be dropped at some point, but for now, let's
not do this, to avoid needing to review all drivers and
the userspace apps.
Acked-by: NHans Verkuil <hans.verkuil@cisco.com>
Tested-by: NJavier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

Due to the MC API proposed changes, we'll need to have an unique
object ID for all graph objects, and have some shared fields
that will be common on all media graph objects.

Right now, the only common object is the object ID, but other
fields will be added later on.
Acked-by: NHans Verkuil <hans.verkuil@cisco.com>
Reviewed-by: NJavier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

Instead of accessing directly entity.id, let's create a macro,
as this field will be moved into a common struct later on.
Acked-by: NHans Verkuil <hans.verkuil@cisco.com>
Reviewed-by: NJavier Martinez Canillas <javier@osg.samsung.com>
Acked-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

Currently, media_entity_init() creates an array with the links,
allocated at init time. It provides a parameter (extra_links)
that would allocate more links than the current needs, but this
is not used by any driver.

As we want to be able to do dynamic link allocation/removal,
we'll need to change the implementation of the links. So,
before doing that, let's first remove that extra unused
parameter, in order to cleanup the interface first.
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>
Acked-by: NSakari Ailus <sakari.ailus@linux.intel.com>
Acked-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

Fix those sparse warnings:
	drivers/media/media-entity.c:238:17: warning: Variable length array is used.
	drivers/media/media-entity.c:239:17: warning: Variable length array is used.

That allows sparse and other code check tools to verify if the
function is using more stack than allowed.

It also solves a bad Kernel pratice of using var length arrays
at the stack.
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

On the place of the source entity name, the sink entity name was printed.
Signed-off-by: NSakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>